A simple Wire Antenna for Preppers

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There have been quite a number of PM enquiries about wire antennas over the last few weeks. Thanks guys. It good to hear that there are now a larger number of us setting up stations, or planning to do so in the near future.

This thread is about setting up the most easily deployable and useable stealth antenna for survivor High Frequency (HF) communications, including CB 27Mhz. the antenna system described works for both transmit and receive. There are far more efficient Ham type installations but they are more complex and are far less stealthy.

I have a good deal of experience with running radio systems both in the field and in stealth mode at various temporary locations on my travels. My antenna of choice is the most simple possible, the end-fed-wire. This is simply a length of wire that is connected to the transceiver at one end.

Pictures speak a thousand words: Attached ate two diagrams, one showing installation of the antenna and one the correct connection sequence of various bits of kit
Here are the thousand words

WIRE:
Wire for the antenna can be any grade available to you, but if given the choice stranded wire in black PVC sleeving is my preferred choice as its durable and OPSEC discreet. It is a common mistake of new erectors of antennas to feel that hugely strong thick wire antennas will outperform thinner wire structures. They will not. We just need our wires to be strong enough not to be blown down in a gale. We also want our antenna wires to be thin enough to be fairly invisible to the human eye.

Any length of wire will do, but some lengths work better than others. For CB : 5.5 meters total length, for HF the ideal length is dependent on minimum frequency to be used 14Mhz = 10 meters, 7,5 Mhz* = 20 Meters and 3.5Mhz* = 40 Meters. Basic rule is to get as long a length of wire in the air as possible. * = NVIS frequencies.
An under eaves dipole wire for CB was discussed by Paul a few weeks ago…. Perhaps he will be able to describe that in some detail to us. ( such an antenna would not have to have an AMU as mentioned below)

Antenna Matching Unit (AMU) IMPORTANT
This device is also called an Antenna Tuning Unit or ATU.
It is used to match ( tune ) the antenna to the transmitter or receiver’s circuits. Considerable receiver improvement can be achieved using AMU.
I consider an AMU and essential piece of survival radio kit. The right one will allow pretty much ANY length of wire to be used as an antenna. This could prove crucial if your antenna gets broken or you have to find new ways to erect antennas at bug out locations. I am recommending two models ( see below) as experience has shown these to be capable for example of allowing me to make transmissions using a barbed wire fence as an antenna ( silly experiment at the time, but now useful learning) The MFJ 971 is recommended as it has an integrated SWR meter which means one less connection to break.

With an AMU of the recommended type in line an emergency replacement antenna can be fashioned from any length of wire thrown into the outside environment.

An AMU can be fairly inexpensively made at home, I will cover this at some time in the future, but for the time being I am recommending commercial units as you will be able to rely upon their performance.

EARTHING the EMU
SEE DIAGRAM.
ABSOLUTELY DO NOT CONNECT UP THE EARTH POINT ON THE AMU TO HOUSHOLD MAIS WIRE EARTH CONNECTION!!!!! ITS DANGEROUS AND WILL CREATE INTERFERENCE NOT JUST IN YOUR HOME BUT AROUND YOUR WHOLE AREA….NOT GOOD FOR OPSEC!!!

The AMU and long wire will work best with a “counterpoise wire” see diagram. This should be 2 to 5 meters of wire attached to the earth post on the ATU. It can be run under carpets, around skirting boards etc. It is important to insulate the end of the wire with electrical insulation tape as it can be at very high voltage that has a slight fire risk. Insulated it will be safe. Also try not to run the counterpoise near or close to house mains electrics.

[b]Wire installation[/b]

Try to run the wire horizontal-ish ( less than 45 degree slopes if possible)
Try to keep the antenna wire as high as possible, but for compromise OPSEC solutions aime for somewhere between 2 and 5 metres off the ground
Antenna wire can go around corners, but corner supports should be insulated

An alternate installation if you have PVC guttering on your house is to run the antenna wire under or in the guttering. Inside the gutter is less good as the wire will detune with rain water build up in that gutter. White gutters with white hi-fi speaker wire for the antenna have been found to work reasonably well, and are fairly invisible.
Reasonable results can be had by just stringing up as much wire as possible in the loft space. This is very stealthy but performance is below that of the ideal external antenna.

A thin wire run as per the diagram will have good performance and will be fairly invisible if the right gauge of wire is selected. Wind is the enemy of this antenna and it needs to be tensioned so as to allow gusts to pull it without stretching it to breaking point. The diagram describes a low tech tensioning system that has proven effective for many amateur long term installations. Weight can be anything from sea fishing weights to bags of sand / gravel. Use your own ingenuity here. For long term use it is a good ides to attach the pulley to the support using galvanized stranded cable ( the stuff sold for attaching TV antenna supports to chimney stacks, is good)

Getting the far end of the wire high in a tree or over a building (for temporary antennas):

A good method is to use a bag of gravel tied to fishing line. Throw that over a tree branch or building roof and than use the line to pull up the paracord.

Insulators:
Do not be tempted to leave out the insulator as the antenna will de-tune if attached to wet paracord. This could damage yoyr transmitter aor burn out the paracord, requiring the antenna to be re rigged.
These can be purchased from ham radio shops but can easily be made at home. PVC plastic conduit is a good material and details of how it can be used are in the diagram attached. I have also had good long life results using cut out sections of Plastic cutting boards that can be found in Pound shops etc. Again, improvisation is key.

Shopping List:

Wire: Maplins have good stocks of both insulated and uninsulated wire.
Very viable alternative is thin (stranded and insulated) hifi speaker cable.

AMU MFJ 901B / MFJ 971/ MFJ 1610
http://www.wsplc.com/acatalog/MFJ-901B_1...s_PEP.html
http://www.wsplc.com/acatalog/MFJ-971_Po..._200W.html
http://www.wsplc.com/acatalog/MFJ-16010_...Watts.html

SWR meter
For HF Look up the Avair AV 20 anvailable on e-bay and a t the Ham radio retailers
For CB ( only) look for something like this:
http://www.ebay.co.uk/itm/SWR-METER-AND-...4605e7d73a

Insulators see Insul 8m here
http://www.wsplc.com/cgi-bin/sh000001.pl...1337#a1337
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