Dirt Cheap Concealable High-Gain Indoor 2-Meter Ham Antenna Project For Beginners

Indoor Antenna

Indoor Antenna

Today we present another article inour non-fiction writing contest – by PrepperDoc

This is a fun, almost novice-level construction project for anyone who has a 2-meter ham radio walkie talkie (e.g., the $26 Baofeng UV-5) and would like more effective range without having to buy an amplifier.  If you are currently using a short rubber-duckie antenna, this high-gain yagi antenna may well make your radio appear to have 6-10 times its power on 2 meters, doubling or tripling your range in relatively open areas, for a total cost about $21.  [Dense high-rise central business city centers may not see as great an improvement, nor areas with impenetrable hills.]  That may just make it possible for you to reach useful repeaters or friends from inside your house.

Using thick multi-ply packing/shipping corrugated cardboard to simplify construction (see the accompanying photo of the completed antenna), this antenna is for indoor or very protected outdoor usage only; it has to stay dry.   This antenna can be “hung” like a large painting on any wall that “points” it in the right direction, as long as there isn’t a lot of metal in the wall, and the house doesn’t have metal siding (or buried rebars).

It can even be covered up with a large poster or a world map, and no one will even know it is there!   This project can help teach newer users quite a bit about radio antennas.   I came up with the idea after building several simple outdoor 2m/70cm yagi-style beam antennas (using a 1″x2″ wooden boom for support) and realized it could be adapted for indoor use.  While my discussion is for the common vertical polarization (elements are aligned vertically) on 2 meters,  it could also be set horizontally if your counterparty is using horizontal polarization.

It will also work on the 70cm band, but my results there are less satisfying.


This antenna was designed for center frequency  of 146 MHz and 440 MHz.  On 2 meters, this antenna will give you roughly 6dB gain over a full size dipole (6 “dBd”) , and probably 12 dB over the stubby “rubber duckie” antenna that probably accompanied your handheld transceiver.  This is because electrically “very-short-for-wavelength”  rubberduckie antennas have low “radiation resistance” and squander most of your transmitter’s power on 2 meters. [1]   Building an antenna like this one is like multiplying your power by 4-10 times!   If you have a favorite repeater, or a trusted ally you need to be able to reach, and a wall that “points” roughly in the correct direction (or even within 30 degrees of the correct direction) you’re in business.

2meter actual test results:   Mathematical patterns based on theory are great, but real-world results are what count.   I actually tested this antenna over a 1/4 mile range (>200 wavelengths, an excellent far field test).   Using uncalibrated signal strength markings on a scanner radio set to the correct frequency (this is the best field strength equipment I currently own), and the same Baofeng transmitter on the same frequency on 2 meters, I sequentially tested:  (1) the supplied rubber-duckie antenna, (2) a top-rated 15” whip antenna (Nagoya NA-771 15.6” dual band) , and (3) this homemade antenna, the results were 0 (zero)  signal strength units for both rubber-duckie & Nagoya whip antenna, and 8 signal units with the antenna pointed frontwards, and 6 signal units turned 180 degrees (“backwards”).   This suggests moderate front-to-back ratio and wonderful forward gain over a whip style antenna–a successful 2 meter high gain antenna..

70cm actual test results:  Unfortunately my current results on 70 cm are not impressive.  While the antenna also works on 70 cm, I can’t promise any significant gain there; it had the same signal strength as the whip & rubber duckie.   On the 70 cm band, the whip/rubber duckie are a more significant fraction of a wavelength, and therefore perform better.  Reception of a local repeater was somewhat better with the yagi than the other antennas, but again the difference was not impressive..  (Improvement may be tedious, but if I ever get it done, I’ll publish how to adjust for better 70cm performance.)

Preparation for Construction 

Construction should take only about 1 hour once you find the following four required items, understand the measurements,  and have your tools at the ready:

  1. 18 feet of 12-AWG solid copper house wire, insulated (THHN) $7   (You can buy this by the foot for about $.36/foot, or you can buy a very short package of 12/2 house wiring, and get the insulated white and black wires from that.   Color does not matter, but it has to have the insulation to use the dimensions below).   The dimensions of the wire DO make a difference, so please use exactly this wire.
  2. RG58A/U coax cable with PL-259 connectors, any length from 9 to 20 feet.                 $7   (You choose the length to suit your needs, can be purchased from Amazon or Radio Shack, I wouldn’t go over 20 feet as the losses in the cable add up.)
  3. If you don’t already have it, you will need an adapter (typically $6.50 on Amazon) from your radio’s antenna connector (often, an SMA) to SO-239 (which is the “female” that fits a PL-259 “male”).  ( If you have a Baofeng UV-5X type radio, the appropriate adapter can be bought from Amazon for $6.50 (see Ref [2] )    Other brands of radio may require the male SMA on the connector, which means they would use the adaptor in Ref [3], also $6.50  )   I like the pigtails to avoid stress on the fragile connections inside the walkie talkie.  Be aware that SOME one-piece adapters (not the ones I’m recommending) come with “metric” threads that do not properly mate with a standard PL-259.
  4. 2-4 layer flat shipping type corrugated cardboard, minimum height 32″, minimum width 41″. The internal corrugation “tunnels” have to be aligned “bottom to top” not sideways, in order to position the wire elements.  (Check out recycling pickup day in upsale neighborhoods and you’re likely to find plenty of this cardboard.)


Balun Center Connection

Balun Center Connection

You’ll need a knife, a way to strip insulation, some 5-minute epoxy glue, and some tape, preferably 2-3″ clear package sealing type tape.   A yardstick or tape measure, and a way to cut the wire.  A drill with a 1/4″ bit would be helpful but not required. You will need some way to secure the two required driven element connections to the coax feedline– this can be a soldering iron/solder, or crimp connectors/crimping tool, or even house-wiring pigtail spiral connectors.  A bit of electrical or any other tape to cover the resulting connections if soldered.

Background Information

Here’s where you get to learn a bit about antennas.   A “yagi” style directional antenna makes your signal (both transmitted and received) much stronger in the desired direction, by not wasting signal or effort on some of the “undesired” directions. [4]   It basically channels much of your transmission and reception into the “desired” sector.   There is a tradeoff:   the higher the gain, the narrower the “favored” region.

Energy is not “created”, its effects are just moved around smartly.   To do this, the yagi has a “driven” element that is connected to the transmission line and does the initial radiation of energy.   Several additional “parasitic” elements have lengths and positions that allow them to capture radiated energy and (in effect) re-radiate it with such a phase adjustment that it modifies the pattern to achieve the proper directivity.

Usually there is one “reflector” and one or more “directors”.   Energy is effectively moved away from the side of the “reflector” and repositioned into the direction of the “directors”.   More directors allow more gain, but there is a point of diminishing returns.

Dipole based antennas like this one usually “work” on their odd harmonics as well.   This antenna uses the same driven element both on its fundamental 1/2 wavelength 2-meter resonance, and on its 3rd harmonic (70 cm band) resonance.   Because of some complicated “end” effects, the point of resonance isn’t exactly 3.000 times the fundamental resonance.  The current pattern in the driven and parasitic elements on their 3rd harmonic theoretically leads to some odd trifurcated forward lobes.    In DK7ZB’s design, he improved the odd trifurcated pattern on the 3rd harmonic by adding additional 70cm-specific parasitic elements.


Cut the insulated wires to the proper lengths as follows.  Each cut should be fairly accurate, say, within about 1/16″ of the desired length.

Driven Element:   Cut two 17.5 inch sections, strip 1/4″ of insulation at one end of each, and bend 90 degrees so that there is a straight section of approximately 17 – 1/8″ and a bare tab at 90 degrees of 1/4″.   You will solder/crimp/connect to the bare tabs.  (See the closeup of the driven element photo.)

Remaining elements:  (Leave all their insulation on)

2m Reflector:  36-3/4″

2m Director #1:  33-5/8″

2m Director #2:  32-7/8″

70cm Reflector:  11-7/8″

70cm Director#1: 11-5/8″

70cm Director #2:  11-1/2″

70cm Director #3:  10-1/4″

70cm Director #4:  10-3/4″

Mark the center of each of those elements with a marker or bit of colored tape.

Cut your cardboard to approximately 41″ wide x 32″ high.  Corrugation slots on the “face” you will insert wires into must be oriented vertically, from “top” to “bottom”.  If you can only find “1-ply” cardboard, use white glue to glue 3 thicknesses together to make 3-ply.

Plan ahead which direction you need to be able to aim this antenna, and how you will hang it on the wall.  (You cannot use conductive WIRE to hang it, but non-conductive string or thin cord is OK.  I glued a yardstick on the back of my antenna,  partway down to allow reinforced holes to hold a hanging cord.)

Figure which sides will therefore be “top” and “bottom”, “front” and “rear”.   Draw a horizontal “antenna centerline”  19″ from the bottom, leaving 13″ to the top. This is so the elements will NOT stick out the bottom and get bent, when the cardboard rests on the floor, until you have it mounted; the 2 meter elements will stick out the top. (Again, see the accompanying photos.)     Plan to insert the 2 meter Reflector about 1″ away from the “rear” edge.   Mark that point, as 0 inches.     Then draw tick marks on your “centerline” at the following distances:

2m Reflector:              0″

70cm Reflector:          4-1/4″

Driven Element:          10-1/16″

70cm Director #1:       11-5/8″

70 cm Director #2:      17″

2m Director #1:           18-1/8″

70cm Director #3:       29″

70cm Director#4:        37-1/4″

2m Director #2:           38-1/16″

You should be able to locate the corrugation “slots” underneath the face of your cardboard surface.   Identify the slot that goes with each of your tick marks.  At the tick mark for the driven element, make two small slits 1/4″ above and below the centerline, and use these to slip the upper and lower portions in, leaving the “tabs” about 1/4″ apart. (See photo.)    Make a small window, about 1/4″ x 1/4″ at each of your other centerline tick marks so that you should be able to see the center mark that you placed on every other wire at the approximate center.   Measuring half the length upwards for every other element (you can use your center-marked elements as guides), make a nick and slide in the element (the 2 meter elements should be inserted from the top edge and will stick out on top).   Using a drop or 2 of glue into the center windows, secure the wire elements so they won’t inadvertently drop away from their correct position.

Using the included illustration, drill or cut 1/4″ holes on the rear side of the driven element, which will allow you to feed the transmission line into a “balun coil” of 4 turns of coax feedline just back from the connection to the driven element.   See the photo of the finished connection to better understand the construction.  Cut off the PL-259 connector at one end of your coax cable.   Starting from the “rear” end of your cardboard, feed the cable in along the centerline, and then run it through the “coil” holes to form the 4 turns of coax.   This forms a “common mode inductor”; this balun (stands for “balanced to unbalance” — the antenna is balanced (symmetrical) and the feedline is coaxial (unbalanced, non-symmetrical) )  and reduces interfering radiation from your feedline.

Now carefully strip off about 1/2″ of outer coax insulation, undo the braiding & twist the fine copper braid wires into one wire; cut off any aluminum foil shielding.   Carefully remove 1/4″ of center conductor insulation.   Wrap the braid wire around the “down” center element’s bare tab, and the center conductor around the “up” center element’s bare tab, and solder (or crimp, or even pigtail twist).   If you solder, insulate the result with a bit of electrical tape.   Use clear packing tape to secure the center connections about 1/4″ apart.

You’re finished; connect the distant PL-259 to the pigtail adapter to your handheld transceiver and have fun!


(Some heavy duty theory)

I got the original dimensions and spacings for this antenna from an open-air boom-based yagi design  published by DK7ZB. [5]   I adjusted the lengths and spacings and built it by sliding wires into the corrugations of cardboard — and it didn’t work!  Something was haywire.  SWR’s (standing wave ratio) were terrible.   Thankfully I have a wonderful measurement device (Ref [6]) that allows me to read resistance and reactance of the antenna on the 2m band (but won’t reach the 70 cm band).   Temporarily using a very short 2 foot transmission line allows the instrument to closely read the actual antenna (longer transmission lines can change the apparent resistance/reactance of the antenna, and create baffling results that remind you of high school questions about resonances of open and closed-end flute tubes).  Starting over with just the driven element showed the resonance was far below the calculated 2-meter band resonance– actually down at 131 MHz.   Additional experiments confirmed that the dielectric effects of both the THHN insulation and the cardboard were making the wire “appear” electrically to be 7% longer.  The resonances observed in a few experiments were as follows:

Resonance Effects Measurements

38.0″ dipole bare wire, free space:                  approx 142 MHz resonance (R = 76, X = 0) [close to expected]

38.4″ dipole insulated wire, free space:          approx 135.5 MHz resonance

(Although the wire was 1% longer, the resonance moved a full 5% lower;  4% lower resonance apparently due to insulation)

38.4″ dipole insulated wire, inside cardboard: approx 131.4 MHz resonance

(Additional 3% drop in resonance due to placement of insulated wire in cardboard.)

After this experiment, I  adjusted all the wire lengths (7% shorter than expected for 146 MHz or 440 MHz as appropriate), rebuilt the antenna (to the dimensions given here) and the 2-meter antenna worked perfectly with an acceptable SWR around 2:1, a good bandwidth, and great forward gain (measured experimentally as shown below).  Because of the influence of the parasitic elements, the resonant impedance of a yagi may not be 50 ohms, hence perfect SWRs do not always result.  The 70 cm antenna had a wonderful SWR but the gain is not impressive.   This can likely be  improved experimentally by adjusting the position of the director elements,  one by one,  with wooden tongs while measuring the far-field strength.   This will be  tedious and I don’t have the time to work on it right now.

If you want to measure SWR on these bands, consider purchasing the Workman 104 VHF/UHF swr bridge ($44) , which also give an approximation of power measurement.  [7]


[1]  For an example of just how much worse a short stubby “rubber duckie” antenna can be, compared to a properly sized antenna, see:   http://blog.g4ilo.com/2011/04/2m-ht-antenna-shootout.html   In  a quasi-professionally done measurement, he observed enormous losses in very short antennas at 2 meters.

[2] For Baofeng-style walkie talkies:   SMA Female to SO-239 Female 6″:   Available from amazon.com at:   http://www.amazon.com/gp/product/B00COKNKS8/ref=pd_lpo_sbs_dp_ss_2?pf_rd_p=1944687762&pf_rd_s=lpo-top-stripe-1&pf_rd_t=201&pf_rd_i=B00ANDSL96&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=178TD40ZXERF5ZF5P4H8

[3] Adapter for radios with SMA-female connector:    http://www.amazon.com/Handheld-Antenna-SO-239-Female-Connectors/dp/B00COW5E3A/ref=sr_1_1?s=pc&ie=UTF8&qid=1440594046&sr=1-1&keywords=SMA+male+to+SO-239

[4] http://www.antenna-theory.com/antennas/travelling/yagi.php

[5] http://www.qsl.net/dk7zb/Duoband/4+5_2m-70cm.htm   Author showed that even his 2meter yagi functioned reasonably well on 70cm; adding specific 70cm directors improved the forward pattern.

[6] http://www.mfjenterprises.com/Product.php?productid=MFJ-259C

[7]  VHF/UHF swr bridge:   http://www.amazon.com/SWR-Power-METER-VHF-Radio/dp/B002KYE190

Prizes for this round (ends October 11 2015 ) in our non fiction writing contest include…

  1. First place winner will receive –  Two Just In Case… Essential Assortment Buckets courtesy of LPC Survival a $147 value, a  Wonder Junior Deluxe Hand Grain Mill courtesy of FoodPrepper.com a $219 value, and a gift certificate for $150 off of  Rifle Ammunition courtesy of LuckyGunner Ammo… Total first place prize value over $516 dollars.
  2. Second Place Winner will receive – A case of Sopakco Sure-Pak MRE – 12 Meals and a Lifestraw Family Unit courtesy of Camping Survival.com, and a One Month Food Pack courtesy of Augason Farms.com
  3. Third place winner will receive –  $50 cash.

The Prepper’s Disaster Communications Plan…

Today we present another article in our non-fiction writing contest –Moira M

You are at home waiting on the cable guy on a drizzly Monday morning. You relax in the quiet house since your spouse is at work, older kid away at college and younger kid in school. You settle in with a nice cup of coffee and the paper, when suddenly the TV show is interrupted for a breaking news bulletin. There have been terrorist attacks in your state capital and two other cities nearby. You grab your cell phone and get a polite message that the system is experiencing technical difficulties and to please try your call again later.

Your home phone has the same problem because it uses Voice Over Internet Protocol (VOIP) and the internet is down. This means no emails either. What do you do? Do you try to pick up the child at the local school? Do you try to make the hour drive to the college to pick up your older child? What will your spouse do? Would you make it to the college only to find that your child had left for home or that your spouse had already picked her up? The best solution in this case would be to have a plan already in place for how to handle the situation and how to communicate when conventional methods fail.

In an emergency whether it is a deliberate act or act of nature, communications can be disrupted. Not only can an increased load on the system cause failures, but the emergency at hand could damage the infrastructure. Storms take out towers and lines all the time. Terrorists could intentionally target communications infrastructure. Not only does it cause a panic when people can’t contact loved ones, but it also prevents people from coordinating to resist them.

In the case of the famous and courageous resistance of the passengers of Flight 93 who tried to retake the plane on 9/11, crashing it in the process, but preventing it from being used against targets such as the White House and other occupied buildings communications played a major role. The people on the plane were able to talk to loved ones to say goodbye.

They were able to talk to emergency personnel and get news of the planes that crashed into the Twin Towers and the Pentagon. Obviously we can’t speak for them, but if they had thought the plane would land somewhere safely in a ransom demand, the passengers may have reacted differently than they did knowing that it was highly likely the terrorists planned to crash the plane into a populated target. The next time, the terrorists may prevent such opportunities.

We live in the age of instant communication. At any given moment you can contact people by phone, text, email, video chat and instant messaging. You can get information on news, current events and any conceivable topic under the sun via the internet, from your wireless device that works almost everywhere. What if that changed?

I used to think it was a convenient plot hole when a movie character was out of cell service at an interstate rest area. That was based on my experience living in Florida. Since then, I’ve lived in Vermont and Tennessee. There are plenty of stretches of interstate highway in those two states without cell service, let alone the remote boondocks locations we would explore. If you have a car accident or breakdown in those places you either walk to find help or hope someone comes along. Your personal emergency may be affected by lack of communication. This can be avoided by letting someone know where you are going so that if you don’t arrive there or get back safely in a reasonable time, then they can search for and potentially rescue you.

In a short term emergency, such as a hurricane, ice storm, blizzard, or terrorist event, there may be more people trying to use cell phones and land lines than the available resources will allow. The nature of the emergency might also knock down transmission lines and towers that provide the services. Many people these days have VOIP phone service (via internet) which requires both electrical power and internet service to work. Long term emergencies, of an apocalyptic nature would likely be the end of these services forever. We would have to turn to other methods of communication.

In the scenario above you could have a plan where one spouse always collects the older child and the other spouse always collects the younger. You could have a plan where you establish which route (and backup route) would be taken so that you could go from the other direction and meet the person, whether it be the college child or the other spouse. You could establish a central crossroads type location where a message could be left that would let other family members know your plan before they go miles in another direction.

There are many alternative methods of communications that we don’t normally use because cell phones are easier to use. If you had a CB radio or long-range walkie talkie, then you could communicate with each other when you were close enough. For emergencies, we should consider setting up some of these methods and including a generator or solar powered method to run them and recharge batteries.

For short term emergencies, it is a good idea for all families to designate one or more people who live far away to be the communications hub. If an ice storm hits Tennessee, then my brother in Florida would be our hub. If my family was scattered when an emergency happened, instead of each of us trying repeatedly (and maybe unsuccessfully) to reach the others, we call my brother to let him know whether we are ok, where we are sheltering and/or how we plan to travel to the others.

He could prevent each of us from traveling to where we thought the others might be sheltering. That would help us to get back together more quickly. The hub person could also serve as a news center if the people in the disaster area had spotty access to news (such as road closures and storm paths), and let extended family know you were safe. Depending on what had happened, CB radios, long range walkie talkies, and ham radio sets could be useful. These radios don’t require the infrastructure as land lines and cell phones. Ham radios require a license and training to use legally.

For long term emergencies communication plans would be more difficult. By long term emergency, I’m referring to anything that disrupts society on a national or worldwide scale. This would include revolution or foreign invasion,  a massive EMP, anything that takes down the power grid, a pandemic or an apocalyptic event. Again, CB radios, long range walkie talkies, and ham radio sets could be useful.

These communications methods could allow you to talk to family and also to get information about what is going on in the disaster. However, the Ham radio license would mean that your name would be on a list. Depending on the emergency at hand, that could make you a target of any group wishing to control the flow of information. Any large antennas could make you the target of anyone looking for a prepared location to raid for food, weapons, and other supplies.

If you don’t have a way to communicate, you would need to have a prearranged plan to meet up. If you’ve ever separated at a Wal-Mart Supercenter and then tried to regroup without cell phones, you can imagine what it could be like. You take the front aisle from produce to pharmacy. Your spouse takes the left aisle from pharmacy to sporting goods. In this fashion, you could walk for miles inside the store without catching a glimpse of each other.

Imagine this on a statewide or multi-state scale with various difficulties in place caused by the disaster. Without a plan you may never see each other again. Depending on the distance, you may decide not to try. If you do want to try, consider setting up a system in advance to improve the odds that you’ll find each other. This is even a good plan to establish with family members living in the same area. If communication is down, but the disaster destroyed the entire neighborhood where the home was located, how would your family get together?

Family homes or other landmarks could be designated in a particular order as meeting points. Meet first at Grandpa’s house. If it is destroyed or in an unsafe area , go to the big tree by the Baptist church, then mom’s house and so forth until the group could meet. In each case, messages could be left in some agreed upon fashion, such as painted on the house or driveway, nailed to a tree, or hidden under a particular rock.

In disaster movies we often see people trying to get together with loved ones and don’t know if they are dead or alive. If your group gets separated at some point or if you have family members living in other areas, you could meet at a central location at a fixed time. An example could be to meet at the eastern end of the Trammell Bridge over the Apalachicola River in Florida at midday on the full moon every month. If that is too much travel, pick one specific time, such as December.

The system isn’t perfect because without a calendar, people may have trouble keeping up with months. Since December includes the winter solstice, hopefully people could keep track of when the days were shortest. In that part of Florida, December would mean colder weather and less chance of meeting up with a poisonous snake. In northern climes, a summer meeting time would be best. Any place or time would do as long as the area would be relatively safe and the date and time could be calculated without a calendar. It could also serve as a place to leave a message without meeting up. You or your relatives could leave a message in code or plain English that gave information or instructions for meeting up.

Talk to your family and set up a plan. Test it occasionally so everyone is familiar with it. Be prepared. Remember that communication is an important step in being prepared.

Prizes for this round (ends October 11 2015 ) in our non fiction writing contest include…

  1. First place winner will receive –  Two Just In Case… Essential Assortment Buckets courtesy of LPC Survival a $147 value, a  Wonder Junior Deluxe Hand Grain Mill courtesy of FoodPrepper.com a $219 value, and a gift certificate for $150 off of  Rifle Ammunition courtesy of LuckyGunner Ammo… Total first place prize value over $516 dollars.
  2. Second Place Winner will receive – A case of Sopakco Sure-Pak MRE – 12 Meals and a Lifestraw Family Unit courtesy of Camping Survival.com, and a One Month Food Pack courtesy of Augason Farms.com
  3. Third place winner will receive –  $50 cash.

A Question for the Pack on Communications

We have all enjoyed this site. I have learned more than I could list. I have learned things here that are just part of me now.

My Multi- part Question to the Pack… What will you.. we.. do when this screen goes blank? In what way can the readers of this site communicate? What ‘hard line’.. ‘hard copy’.. method(s) have you… we.. set up to provide some continuity of communications? Yeah yeah…. Ham… CB… But what else is there unless you… we… have pre-set a system in place now? I ask as a result of the conversation on ‘Underground Railroading’ and ‘Net Works’ to provide help in a post SHTF event(s). Some of our listening audience(s) would call the very subject treasonous…… Any comments…. anyone… Beuller… anyone.. NSA… Beuller?

With regards… Tom The Tinker

Books and two way radios…

Question from a reader about medical books and two-way radios…

HI MD, love your site and am slowly based on money starting to become a prepper, Question how do you compare Survival MD to where there is no dr.? I would like to buy Survival MD but they no longer offer the $22 and they don’t respond to emails either. The cost now is $37 and I can get where there is no Doctor around $13. Do you think this is a good book compared to Survival MD? I value your opinion as I know little about this stuff other then what i read on your site and posts. Also is there a decently priced two way radio that will transmit a legitimate 5-10 miles in a mountainous area that you are aware of > thanks for you help and keep updating your site. Ron

M.D. Replies: Where there is no doctor (and Where there is no Dentist) is a great​ medical book for preppers, the difference between the two is that “Where there is no Doctor” offers more primitive type care and tips on staying healthy. The book was put together for missionaries to help villagers living in a primitive conditions, like a remote villages in Africa for example. This is very good info to have in a long-term grid down situation. Survival MD is geared to preppers who have limited medical training / skills but who have put back medical preps in advance.

Get “Where there is no Doctor” first and then just skip Survival MD because of the fact that they raised their price and won’t answer your emails, and get The Survival Medicine Handbook: A Guide for When Help is Not on the Way. This book is just as good if not better and covers the same info.

As for handheld two way radios, they have a realistic reliable range of 1-2 miles in mountain areas, with the actual range depending heavily on where each unit is located. Mountain top to mountain top without obstruction range can be impressive at 5 miles or even more, but can be cut down drastically if say there is a hill between the units. This will decrease the range significantly.

I like the MURS radios because they are not used by most people and you’ll pretty much have the frequencies to yourself and that equals better privacy, than say using CB or GMRS type radios. But with any commonly available two-way radio communications privacy is not guaranteed.

Shortwave Ham Radio Communications with the Grid Down — Will Your Inverter Drown Out All Signals?

Today we present another article for this round in our non-fiction writing contest – by PrepperDoc

In a grid-down scenario, many will turn to radio for strategic information and advance warning of coming adversaries.  Hand-held VHF walkie-talkies will be quite range-limited if their usual repeaters go down also.   CB radio may allow 5-10 mile range, and marine radio slightly more, both depending on antenna height.

Short wave (high frequency, “HF”) ham radio will uniquely allow direct two-way communications both locally and over statewide and nationwide distances.    Many are planning on this as their primary long distance communications. Unfortunately, if they are relying on DC inverters for AC power, they may be stunned to find overwhelming hash interference coming from the high frequency switching Field Effect Transistors (FET) in their own inverter!   In that situation, they may have to temporarily turn off their inverter power source, and turn to battery-powered low-power (“QRP”) ham radio transceivers, or simply monitor battery-powered AM/FM/shortwave broadcast receivers.

I learned this the hard way.  Unaware of this problem, I had a very elaborate solar power system installed, using widely available robust and powerful equipment  (Out Back Power, www.outbackpower.com).   The first time I tested my setup on “emergency battery power,” I was surprised to have significant, wideband hash noise that was coming from my own power system.   Adding hefty inline EMI (electromagnetic interference) power line filters right inside the inverter AC panel boxes calmed down the interference to just above background level, very tolerable.  Not all inverters produce the same level of interference.  A friend who has a MagnaSine 4kW inverter (Magnum Energy, magnumenergy.com) doesn’t seem to have the problem.

Now aware of the problem, and concerned for allies in my area (whom I want to be able to hear my signal!), I did experiments on a couple of different small inverters and some possible filtering solutions, measuring the received signal or interference at 3.7 MHz, in the middle of the 80-meter ham band that can be used for statewide or national communications after sundown.

I used a venerable Heathkit SB-102 vacuum tube transceiver as the test receiver, and to somewhat quantify the amount of interference versus typical signal strength, I measured the interference using the S-unit meter display of the receiver.  S-units are a relative and uncalibrated indication of how strong a received signal is, created by automated receiver circuitry that tries to automatically adjust the speaker volume despite widely varying signal strength.

Different receivers may grade the same signal quite differently. My receiver seems to grade signals rather conservatively (giving fairly low S-values).   However, each increase of 1 S-unit reflects a significantly easier to hear signal.   Background atmospheric noise randomly moved between S1 and S2, while black clouds and lighting ten miles away produced S6 lightning crashes.   Such nearby lightning will generally wipe out almost all signals.  Strong and easily readable voice single sideband signals were reading S3 or S4 on my receiver.

The Table below presents my results of interference signal-strength measurements:


Power Source: Household AC Modified Sine Wave Inverter [1] Pure Sinewave inverter [2]
No powerline filter Background S1-S2

Nearby lightning S6

S3 hash S6 hash
Schaffner EMI filter [3], ungrounded S1-S2 (barely noticeable) S3 hash
Schaffner EMI filter [3], grounded to household power ground S1-1/2, not discernible S2 hash, somewhat above background noise
Homemade jerry-rigged EMI Filter [4] No improvement at all (S3) No improvement at all (S6)

Surprisingly, the cheaper modified-sine wave inverter creates significantly less wideband (hash) interference than the low-power but higher quality sine wave inverter (which may have faster-switching FETs).   Both of these inverters are relatively small, portable, relatively low-priced inverters that can easily be stored in a small Faraday cage at home and might well be chosen as a grid-down backup device.   Both produce adequate power for a small vacuum tube ham radio (relatively EMP-resistant) with roughly 75-100 watts output.  The 2500-watt modified sinewave inverter can start and run a refrigerator compressor.  The interference from either would drown out most signals without power filtering. Both inverters were on a different floor from the receiver (which had a coax transmission line to an outside wire antenna) and a long extension cord went from inverters to the room with the ham radio.  Interestingly, the interference seemed to be conducted via plugging the receiver into the output AC power from the inverters — simply having the inverter-powered extension cord in the same room as the receiver did by itself not cause problems.

Interference from solar power inverters has been widely recognized and comes in two flavors, usually simultaneously:   differential mode (signal on hot and cold AC wires is 180 degrees out of phase) and common mode (signal on hot and cold AC wires is the same, and significant versus ground).  [5]
A jerry-rigged homemade attempt at a power line filter [4] was completely ineffective.   Apparently one needs higher inductance and capacitance values, and likely a split capacitor with the center tap grounded to reduce common-mode interference.

Placing an inexpensive 20-amp rated commercial EMI filter inline virtually eliminated the interference from the modified sine wave inverter, particularly when the ground tap on the filter was connected to my house wiring ground.   The same filter reduced the more potent interference from the sinewave inverter to an acceptable — but still noticeable — level when the ground connection was used.    Without the ground connection, such filters reduce only differential-mode interference; the ground connection increases the possibility of reducing common-mode interference.

This type of harmonic interference from the fast switching pulses of a DC-to-AC inverter will vary from brand to brand, and should become weaker at higher frequencies.  I did not test to see if it is troublesome at CB frequencies (27 MHz) but I would expect much less of a problem,  and I would doubt that it would be a great problem at 2-meter frequencies.   However, if you are depending on an inverter for your sound-signature-safe alternate power supply, and wish to have long-range ham radio communications, it would be wise to test your setup and/or purchase some form of EMI filtering and add it right at the output of your inverter before long power runs to portions of your house or your ham radio equipment.  It’s an easy, cheap and effective fix.


[1] Whistler PRO2500W  2500 watt power inverter, 12 volt car battery source. Inverter ungrounded.

[2] Morningstar SureSine300.   300watt (peak 600 watts 10 minutes).  12 volt car battery source. Inverter ungrounded.

[3] Schaffner FN2030A-20-06 Power Line Filter, rated 20A AC, purchased from Mouser Electronics, www.mouser.com,   details at:  http://www.mouser.com/ProductDetail/Schaffner/FN2030A-20-06/?qs=%2fha2pyFadujyPQkwXmbiEp4v1SwIQD%2faY%2fbAgajTvcbbNdiK%2fOAztg%3d%3d

[4]  Homemade filter consisted of series open wire coils approximately 20 microhenries (40 turns, 1.5″ dia) and a homemade shunt capacitor on the load side made with 80 sq. inch aluminum foil plates separated by 20 pound copy paper, measured as approximately 2000 pF.

[5] http://forum.solar-electric.com/forum/solar-electric-power-wind-power-balance-of-system/advanced-solar-electric-technical-forum/4685-radio-noise-from-pv-system

Prizes for this round (ends July 10 2015 ) in our non fiction writing contest include…

  1. First place winner will receive –  A case of Yoder’s Canned Bacon (12 cans, $169.95), a case of Future Essentials Canned Green Coffee Beans (12 cans, $143.30 value), and a case of our Future Essentials Canned Breakfast/Cold Cereal Variety with Milk (12 cans; a can each of Raisin Bran, Rice Krispies, Corn Flakes, Apple O’s, Whole Grain Frosted Wheat’s, Cocoa Rice Krispies, Honey & Nut O’s, Fruity O’s and Frosted Flakes, as well as three (3) Cans of Powdered Milk Substitute (18 oz. each) – (a value of $62.90) all courtesy MRE Depot and a  WonderMix Bread Mixer courtesy of FoodPrepper.com a $300 value. Total first place prize value over$674.
  2. Second Place Winner will receive – A Royal Berkey water filter, courtesy of Directive 21 (a $283 value) and an autographed copy of 31 Days to Survival
  3. Third place winner will receive –  A gift certificate for $150 off of Hornady Ammo courtesy of LuckyGunner Ammo.

Introduction to EMP and Faraday Cages

Also see: Build Your Own Faraday Cage. Here’s How.

Understanding the RadioShack SWR & Power Meter

By PrepperDoc

Many new hams, CB operators, and even boaters with a marine radio get their first standing wave ratio (SWR) meter from a convenient RadioShack. An antenna with an SWR greater than 2:1 may be in need of work! If you use an antenna tuner to match a “long-wire” antenna, then this device is indispensable.

sw figure 2


Their catalog # 2100534 fills the bill, but unfortunately the panel layout & markings may easily lead to confusion. Exactly what does one do with the three switches and the knob? Friends whom I’ve tried to help were completely lost because the front panel intersperses switches for the two different capabilities of this meter.

Figure 1 shows improved panel artwork with thick borders that more clearly separate the functions and better explains the controls. Using a photocopier’s enlarge/shrink function, make the top border about 3-3/8″. Cut out the switch rectangles and knob circle. Then tape it over the commercial front panel…

sw figure 1

Now to explain the meter’s operation: The instrument has two completely separate functions: measuring output POWER and measuring Standing Wave Ratio (SWR). The middle switch chooses which function.

To read POWER, the user moves the middle switch to its highest position, then selects from three different power ranges with the left-most switch. Both “average” and “peak envelope power” (PEP) can be measured, depending on the setting of the right-most switch.

In voice single side band, the PEP can be quite a bit larger than the average, and thus this meter can help the user avoid turning the mic gain up so high that he splatters his signal, taking up much more bandwidth than proper. (If turning up the mike gain no longer increases the PEP output, for sure you are beyond the limit! Back off a bit!) The rotary knob isn’t used at all.

To read the SWR, the user first positions the middle switch into the “FORW CAL” (forward relative power) position, sends out a steady signal (careful not to do this longer than safe for your transmitter’s amplifier!) and quickly adjusts the rotary knob on the right until the needle is at “full scale”.

There are multiple ways to create the steady carrier needed to allow the adjustment, depending on your transmitter: there may be a “TUNE” position; or you may be able to hold your Morse Code key down, or with an AM CB rig, simply push the mike button. Then flick the middle switch into REV (“reverse relative power”) and read the SWR from the top scales marked SWR on the meter. Try to keep your SWR 2:1 or lower!

Figure 1: Artwork for new panel markings.
Figure 2 — New artwork on SWR / Power meter

Reliable Ham Radio Post-Disaster Security Communications

Today’s non-fiction writing contest entry  written by PrepperDoc

antennaMany preppers’ post-disaster communications plans are built upon low power (“QRP,”  typically 1-5 watts output power) ham radio equipment, able to easily obtain power from small battery or low-power solar sources.    They may believe that after a disaster, interference from higher-powered stations, noisy power lines, electric motors, and a host of computers will be squashed, and their 5-watt level signals will easily make all the necessary communications.  Depending on their communications requirements, they may be badly disappointed in the real event!

Survivors may have widely varying communications needs which might be broken down roughly into three categories:  1) ability to listen to (and possibly contribute to) news reports to/from undamaged states or nations;  2) ability to obtain same-city, intra-state and next-state-over reports of situation-on-the-ground (5-300 miles);  3) short-range communications within a neighborhood.   #1 is easily handled by low-power ham gear (or even shortwave radio receivers) because there may be multiple possible transmitting stations from which to choose; simply find one you can hear.   #3 can be handled by direct (simplex) communications using low-power walkie-talkie FRS/GMRS or ham transceivers.  (Store several in a Faraday cage!)   It is middle-distance #2 — reliable communication/information gathering from 5-300 miles — that is problematic.   You may find a network of several reliable early-warning sites in nearby cities and just across the state border, and have a need to maintain RELIABLE  (not hit-or-miss) communications with them daily for updates on security issues.   It is nice to know of oncoming trouble farther than “smoke-distance.”

VHF/UHF walkie-talkies simply can’t fill this need with their line-of-sight propagation.   And ground-wave (limited at any frequency above 3.5 MHz) transmissions will not cover the distance.   One report found 7MHz ground wave unreliable even at 15 km.   This 5-300 mile range is the realm where Near Vertical Incidence Skywave communications (NVIS), bouncing near-straight-up radio waves off the ionosphere miles above us (usually the F layer but sometimes the E layer) is the only suitable propagation system.  [1]

The properties of the F layer are important to your success.   First, it is at least 150 km above the earth, so your signal is going to travel 300 km just to get to the other side of your town.   Modeling your antenna as a point-source, your signal is going to be significantly dispersed and therefore much weaker after traversing that 300 km round-trip distance!

Secondly, the F layer has variable ionization (more during the day, and during maxima of the 11-year sunspot cycle) and is only able to reflect signals at any given moment up to a certain “cutoff frequency” that depends on the both the ionization and the angle of incidence.   Vertical signals (needed to get to the other side of your city) are the hardest to refract/reflect.   The maximum frequency that successfully reflects vertically is called the Critical Frequency.    Somewhat higher frequencies may refract at lesser angles — but constrained by geometry, they will come back down much farther away, leaving you with a “skip zone” of impossible communications.

And unfortunately, you probably can’t use the exact OPTIMAL frequency at any given circumstance. Your prospective counterparties are mostly other amateur radio operators.   Ham radio equipment typically is designed to work only in certain designated frequency bands — the 3.5-4  MHz (“80 meter”) and 7-7.3 MHz (“40 meter”) are usually the key ones for reliable NVIS communications.   During nighttime around sunspot minima, only the 3.5-4 MHz band may be functioning for NVIS.   During the day, both 80 and 40 meters may reflect in more years of the sunspot cycle — but now add in the problem that the lower level D layer, activated by sunlight-accompanying xrays,  will all but wipe out 80 meter communications.   The D layer’s power-absorption declines by the square of the frequency.  As a result, you prefer to use the very highest frequency that works, optimally just below the critical frequency.  During daytime, the critical frequency may be 7MHz or even much higher, but many ham transceivers off only 7MHz,  14MHz, 21MHz & 28MHz choices.   Thus you may have additional D-layer absorption due to sub-optimal communications frequency.  During the night, the sun’s xrays disappear, and the D layer dissipates, so 3.5-4 MHz signals, which are usually safely below the critical frequency even during sunspot minima, become much more useful & important. For reliable nighttime NVIS, you probably need 80 meter capability, which requires large antennas for good efficiency (or else higher power).  [2]

The ultimate goal is simply to provide a signal to the desired receiving station that significantly overpowers the NOISE that the recipient encounters.   Inexperienced operators may require signal-to-noise ratios of 10 dB or more for successful communications.

Even after an EMP-type disaster, there may be more radio noise than optimistic low-power proponents expected.  Why?  Because much of the radio noise in the high frequency bands is the result of tens of lightning strikes every second, all over globe, whose radio-signature is carried around the world by the ionosphere just like any other radio signal. [3]   Even after an EMP, this noise source will still exist.   Further, ham radio stations in undamaged nations will still be on the air — and likely far busier than ever before!  There will be plenty of strong signals with which to contend.   Finally, while power lines may be silent and most computers dark, a new source of man-made radio interference may burst forth–dozens to thousands of power inverters of all types providing power to persons all over your city.   Even the sine-wave inverters have powerful switching signals as part of their makeup, and I was surprised to find a very troublesome amount of interference coming from my very own backup power system,  wiping out weak-signal reception!   The addition of a heavy-duty filtering device in my inverter’s power lines to my home knocked this down considerably, but few survivors are going to have prepared this well, so houses all around you may be radiating radio hash.  (Consider a device similar to:   http://www.amazon.com/Power-Single-Phase-Filter-CW3-20A-S/dp/B00D0U83D8/ref=sr_1_8?ie=UTF8&qid=1428329468&sr=8-8&keywords=power+line+filter )

For NVIS communications, your antenna can also squelch your effort to overcome the noise at your intended recipient’s site:  vertical or whip antennas put relatively little power straight up, further damaging your low-powered transmitter’s chances.   A very comprehensive investigation in the Netherlands demonstrated that a horizontal resonant dipole at 0.15 – 0.2 wavelengths height was optimal [4]  (corroborating work done in the rainforests of Thailand).   For an 80-meter antenna, that means a height in the range of 40 feet; for 40 meters, 20 feet.   Survivors with antennas at first-story roof-level may face a significant power loss of as much as 90% of their effective signal (10 dB).   Likewise, too-high an antenna (from a skyscraper) may also lower vertically incident power.

You can reduce the effective noise (and thus improve your chances) by eschewing voice communications and moving to narrow-band techniques such as Morse code or digital communications — IF your receiver has the ability to filter more narrowly, your operator has the required experience, and in the case of digital, your conversion equipment survived the disaster.   In our group, we have some new operators who simply cannot use these more-powerful techniques, so we are limited to voice (single side band, about 2 kHz bandwidth).

Beginning to see why QRP low-power ham radio may not meet your security communication needs post-disaster?  Basically, there were very good reasons why the most popular ham radio gear of the 1960’s and 1970’s offered a full 100 watts of output!   Furthermore, what if there is a second EMP strike? Or third?   Will your transistorized low-power ham radio is connected to an antenna during one of those strikes because you depend on it for communications?   It may well be destroyed.    The most impervious gear to simulated EMP attack in testing was vacuum tube gear:  the type of transceivers that had the 100-watt output.

So what is documented about successful and reliable short-to-mid-range NVIS communications in the real world?   Working in the rainforests of Thailand, with relatively optimized antennas, 15-watt output transmitters were reliable for NVIS communications 80% of the time.   My own group found that with newbie operators and horizontal dipoles at various heights, cross-city (30 mile) communications were sometimes possible on voice, and even more likely on Morse code, but that experience made a very big difference.    A Netherlands group did extensive research at a near-optimum frequency of 5.39 MHz for their conditions, using a high-power 850-watt output transmitter and had excellent signal to noise ratios of 50 dB in NVIS communications.[4]   Their powerful transmitter even showed evidence of a readable signal that may have been carried the other way–traversing almost the entire globe to reach their recipient; but this signal was some 40 dB weaker.   Their advantages over many low-power stations were significant:   Their 850 watt station was 22 dB stronger than a 5-watt QRP station,  had an optimized antenna (possibly 10-20 dB better than a poorer antenna) and optimized frequency (excessive D-layer absorption due to lower frequency might have added another 10-20 dB of loss).   Hence their 50 dB signal to noise ratio could easily have been obliterated by a ham operating a 5-watt station (-22 dB), with a suboptimal antenna (-15 dB) and suboptimal frequency (-15 dB)  (total degradation:   52 dB) even before considering the difficulties of inexperienced operators.  An excellent advisory on NVIS emergency communicates notes success with 25 watt (output) signals. [5]

My conclusion is that your communications preparations should definitely include a simple wire dipole antenna at 30-40 feet, either resonant or long-wire horizontal dipoles (with antenna tuner) for both 80- and 40- meter ham radio bands, and possibly additional higher frequency bands for daytime use.    You should also develop a healthy dose of experience (Morse code ability and a narrow receiver filter would be great!).   But it is obviously easier to “turn down” the transmitter power on a 100-watt (or higher) tube type rugged EMP-resistant vacuum tube transmitter to save energy, than it is to try and make a low power 5-watt QRP transistorized transmitter communicate amidst stronger signals and broadband inverter-generated hash interference, while worrying that your equipment might at any time be destroyed by a follow-up EMP strike.    So it might be worth it to plan ahead to provide both ham radio equipment and electrical power for a higher power transmitter, even if you do succeed at times with a QRP transceiver.



[1] NVIS Army FM 24-18.  Appendix M with Graphics.    http://kv5r.com/ham-radio/nvis-army-fm-24-18/   (An excellent tutorial.)

[2]   HF Near Vertical Incidence Skywave (NVIS) Frequency Band Selection.    Accessed at:   http://www.idahoares.info/tutorial_hf_nvis_band_selection.shtml

[3]   Bianchi C, Meloni A:  Terrestrial Natural and Man-Made Electromagnetic Noise.  Accessed at:    http://www.progettomem.it/doc/MEM_Noise.pdf

[4] Witvliet BA et al, Near Vertical Incidence Skywave Propagation:  Elevation Angles and Optimum Antenna Height for Horizontal Dipole Antennas.   Accessed at:   http://www.agentschaptelecom.nl/sites/default/files/2015_-_witvliet_-_nvis_elevation_angles_and_antenna_height_-_ieee_ant_prop_mag.pdf

[5] Idaho Amateur Radio Emergency Service, HF Near Vertical Incidence Skywave (NVIS) Frequency Band Selection.  Accessed at:   http://www.idahoares.info/tutorial_hf_nvis_band_selection.shtml

Prizes for this round (ends April 23 2015 ) in our non fiction writing contest include… Please send your articles now!

  1. First place winner will receive –  A  case of six (6) #10 cans of Freeze Dried Military Pork Chops a $300 value courtesy of MRE Depot, and a  WonderMix Bread Mixer courtesy of FoodPrepper.com a $300 value and five bottles of the new Berkey BioFilm Drops a $150 value courtesy of LPC Survival – total prize value of over $750.
  2. Second place winner will receive –  A gift a gift certificate for $150 off of  Federal Ammunition courtesy of LuckyGunner Ammo.
  3. Third Place winner will receive –  A copy of my book ”31 Days to Survival: A Complete Plan for Emergency Preparedness“ and “Dirt Cheap Survival Retreat” courtesy of  TheSurvivalistBlog.net and copy of “The Survival Medicine Handbook” courtesy of www.doomandbloom.net.

Two-WAY Radio Communications Basics for Preppers

Today’s non-fiction writing contest entry was written by Hunter Prepper

There are no hand held radios that will ever cover any kind of range (beyond LOS (Line of Sight)) without some kind of special circumstances or a repeater. The laws of physics, solid matter and the curvature of the Earth simply get in the way. So, here are your realistic options for achieving long (er) range.

Amateur Radio (Ham) can offer coverage from a few miles to thousands of miles, depending on the band and equipment used. Portable VHF/UHF (Very High Frequency/Ultra High Frequency) radios will have a range by themselves of a few miles, usually less than 10, but can increase that range dramatically through the use of a repeater. HF (High Frequency) radios with good antennas can offer ranges of hundreds or thousands of miles depending on the band, time of day and atmospheric conditions. Repeater sites can fail and atmospheric conditions can be severely disrupted by solar activity, so depending on this is still a gamble, but it is by far the best option for reliable communications range.

General Mobile Radio Service (GMRS) High-end GMRS radios operate similar to UHF Ham radio equipment. GMRS users can use up to 50 watts, high-gain antennas and they can even use and own repeater sites. This is not going to happen using the common bubble pack available as a 22 channel pair of radios. You need real radios, such as the Motorola or Vertex variety. Hand held radios are not going to get more than a few miles range without some unusual circumstances or a repeater.

All other radio services are simplex or point-to-point and don’t offer repeaters, therefore limiting the radios range to no further than the horizon. Radio waves do not follow the contour of the terrain, they operate in strait lines, and any object of sufficient size will block them. What this means is, that they will not go through mountains, nor will they go over the mountain and back down the other side. They will not penetrate buildings very well, travel through dense vegetation such as a forest very well or follow the curvature of the Earth. Radio waves of sufficient power and that are below a certain frequency can be reflected off the upper layers of the atmosphere, but this is dependent on things such as time of day and solar activity.

The only reliable way to get communications range more than a few miles is to install antennas on tall masts or towers (you can hang them in trees) and with sufficient power and provided the terrain isn’t too mountainous and in the way, then you can begin to get some reliable and consistent range out of your radio system, but expecting a hand held radio to offer coverage of more than a few miles is asking too much. Hand-held Ham, GMRS and MURS (Multi Use Radio Service) radios on VHF and UHF frequencies will offer a standalone range of a few miles over average terrain. The FRS (Family Radio Service) bubble pack radios, that you can buy at a Wal-Mart or Academy Sports for example, can only be expected to be reliable at distances measured in yards rather than miles.

Here a few major things that limits your ability to talk to your buddy. This may be oversimplified, but I hope it will help you start to understand the big picture.

Propagation: This is the pathway of the radio waves you send to your buddy. If they are in LOS (line of sight)–which means you could actually see him if you could see 30miles–then you simply need the right antenna and power level to talk to him.

Most of us don’t have line-of-sight to the people we want to talk to. Usually trees, buildings, mountains or other barriers block the signal. They turn the “36 mile” radios into the 1 mile radios you have! There are a few ways to combat these problems, and this brings us to the next point.

Antenna design: There are antennas out there designed to “focus” your transmitting or receiving into one direction. Kind of like a flashlight you can point in any direction you choose. They are called “directional” antennas and have design names like “yagi”, “quad” or “log periodic”. Old analog TV antennas are commonly a yagi or log periodic design–that’s why you rotate them to get the best signal.

Anyway, if you and your buddy point these directional antennas at each other you will stand a better chance of hearing each other. Because they are physically large they almost always used at fixed locations like a home.

Other antennas are designed to broadcast in all directions. They are called “omni-directional”. Much like a light bulb, they send their energy out in all directions. It’s the type of antenna used by police cars and walkie talkies. However they aren’t good for talking over long distance unless you feed them some serious power. But sometimes you can use a radio with a directional antenna pointing at someone with an omni… and still have a good result.

Antennas do best when they are used at the highest geographical point. It gets you closer to the LOS mentioned earlier; you can better your position by transmitting from the top of a hill, from the highest floor of a building, or from an antenna on top of roof, mast or tower.

One more note. Your antenna needs to be tuned to the frequency you are using. This makes your antenna as efficient as possible. This efficiency is a huge concern–and it brings us to the next topic. (Tuning your antenna is too much info to put into this article, do your research and learn)

Power: You have to use enough power to create a signal that reaches your buddy. The best antenna in the world won’t work if you don’t feed it enough juice. And the most juice in the world won’t make your antenna work of its not tuned.

The general rule of communication is to use only as much power as you need. This is courtesy to others who use the same or nearby frequencies. You don’t want to overpower them. Also, it helps save money on your electric bill!

Summary: To achieve constant and reliable 30 mile range, You need to use enough power WITH a tuned antenna AT the best height you can manage.

The inexpensive FRS or GMRS radios (like the Motorola Talkabout radios) won’t do it. They put out a maximum 0.5 watts of power (half a watt!) Their antennas are very inefficient. However, they would be good for communications on your property.

Other public radio frequencies such as MURS band have very limited power output–2 watts.

CB radio can legally put out 4 watts. There’s also a mode feature that allows 12 watts in “single sideband” mode. It’s also referred to as “SSB”. Your voices will sound funny due to the mode, but it is a much more efficient use of your radio’s power. CB antennas tend to be long or very big. It will take some experimenting to find the best antenna position to use. You will also need to “tune” the antenna for optimal performance.

The only way you’re going to legally talk to your buddy with a relatively compact antenna and good audio quality is to get into Amateur Radio. It will enable you to use higher power (some mobile radios can put out 75 watts), and there are many antenna options for home and mobile use. I know not everyone wants to register with the Government, but sometimes it has its advantages. Besides just because you have a license does not mean you have a radio, if you understand. There is also no law against buying the radio “just” to listen.

If you choose amateur radio, you will likely need a mobile car radio that puts out 50 watts or more into a tuned mobile antenna that is not too short. You can use the same radio in your house… with a better performing antenna on the roof, inside the attic, or on an antenna mast. By having a radio of this type you will be able to have a mobile station and a base station using one radio and two antennas.

There are many, many other more involved options and details such as grounding, repeaters, etc. It is hard to cover everything in a single post, it is best to get a good book; I started with “HAM radio for Dummies” and one from the ARRL (Amateur Radio Relay League). But hopefully this will help you ask more questions.

Abbreviations and Explanations: VHF – Very High Frequency; is the ITU-designated range of radio frequency electromagnetic waves from 30 MHz to 300 MHz. Frequencies immediately below VHF are denoted high frequency (HF), and the next higher frequencies are known as ultra high frequency (UHF).

VHF propagation characteristics are ideal for short-distance terrestrial communication, with a range generally somewhat farther than line-of-sight from the transmitter (see formula below). Unlike high frequencies (HF), the ionosphere does not usually reflect VHF waves (called skywave propagation) so transmissions are restricted to the local radio horizon less than 100 miles. VHF is also less affected by atmospheric noise and interference from electrical equipment than lower frequencies.

Whilst it is blocked by land features such as hills and mountains, it is less affected by buildings and other less substantial objects than UHF frequencies. UHF – Ultra High Frequency; designates the ITU radio frequency range of electromagnetic waves between 300 MHz and 3 GHz (3,000 MHz), also known as the decimeter band or decimeter wave as the wavelengths range from one to ten decimetres; that is 10 centimeters to 1 meter. Radio waves with frequencies above the UHF band fall into the SHF (super-high frequency) or microwave frequency range.

Lower frequency signals fall into the VHF (very high frequency) or lower bands. UHF radio waves propagate mainly by line of sight; they are blocked by hills and large buildings although the transmission through building walls is high enough for indoor reception. They are used for television broadcasting, cordless phones, walkie-talkies, satellite communication, and numerous other applications.

I hope this has helped you or at least guided you in making an informed decision on what to purchase and what you can expect for your purchase.

Prizes for this round (ends April 23 2015 ) in our non fiction writing contest include… Please send your articles now!

  1. First place winner will receive –  A  case of six (6) #10 cans of Freeze Dried Military Pork Chops a $300 value courtesy of MRE Depot, and a  WonderMix Bread Mixer courtesy of FoodPrepper.com a $300 value and five bottles of the new Berkey BioFilm Drops a $150 value courtesy of LPC Survival – total prize value of over $750.
  2. Second place winner will receive –  A gift a gift certificate for $150 off of  Federal Ammunition courtesy of LuckyGunner Ammo.
  3. Third Place winner will receive –  A copy of my book ”31 Days to Survival: A Complete Plan for Emergency Preparedness“ and “Dirt Cheap Survival Retreat” courtesy of  TheSurvivalistBlog.net and copy of “The Survival Medicine Handbook” courtesy of www.doomandbloom.net.