Making contact by FM radio

[Skvez]

If the transmitting aerial is horizontal then most of the power goes only at right angles to the line of the aerial and you 'loose' a lot of power transmitting up and down. Also the receiving aerial needs to be in the horizontal plane for good reception efficiency. This is fine perhaps ever preferential if you know where you're transmitting towards (and want to minimise the chance of interception) but for general broadcast you want a vertically aligned aerial.

[Skean Dhude]

Interesting. How do the US DoD do this with the VLF antenna which cover large areas of land? No way does that go up in the air.

[Skvez]

The lower the frequency the less directional but the footprint of a horozontal aerial is far from circular

[Skean Dhude]

Makes sense and with a wavelength that size it probably covers the solar system anyway.

[Bald Carl]

Ex-scaleyback here.

My VHF/hf days were a few years ago now and my knowledge is rusty although I am prone to chattering out a bit of morse on my teeth now and then!

This technology is only used now by hobbyists. I would say its not worth pursuing unfortunately. If you are in a big group, hand held personal radios are the best bet. The range is upto a couple of K's.

Mobile phone coverage would last last 24 to 72 hours if anything kicks off (my field of expertise nowadays)

[bigpaul]

I just wondered, if you are transmitting can TPTB triangulated your position, like the Nazis used to do in WW2?? i'm not technically minded to start with, so whilst i have a wind up radio to receive news will be keeping a low profile especially after TSHTF.

[Skean Dhude]

All transmissions can be triangulated. It is easy to do with simple receiver of that frequency.

Mobiles, CB, Walkie Talkies,etc. If it transmits you can locate it while it is transmitting.

[bigpaul]

(15 November 2011, 13:06)Skean Dhude Wrote: All transmissions can be triangulated. It is easy to do with simple receiver of that frequency.

Mobiles, CB, Walkie Talkies,etc. If it transmits you can locate it while it is transmitting.

thats what i thought, after TSHTF the mobile gets chucked away and i keep a VERY low(i.e.hidden) profile.

[Bald Carl]

Any transmitter can be triangulated (DF'd). Simple measures can counteract this. Maintain radio silence (self defeating in a way) and keep radio transmissions to a minimum. Do not transmit for more than 20 secs so as to provide less of an opportunity to transmit your location.

Mobile phone operators use distance to base station calculations to determine locations for as long as the mobile is switched on.

Unless you are a major criminal, I wouldn't worry about things like this.

[NorthernRaider]

Guys can I chip in on this subject, I dont know much about radios but in my archive I did have this article about the MT5050 radio because its got some erm...... special attributes that I think you chaps wanting some affordable powerful PMR radios may be interested in.

Look up this URL and read the whole review especially the bottom bit.
Intek MT 5050 proferssional PMR 446 radio review

http://www.transmission1.co.uk/2008/09/i...io-review/

NR

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Forgot to add I'm keen to learn and am thinking about PMR 446 instead of CB radios for my kit.

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Erm may I suggest you take a peek at this URL that refers to the UKs erm...... Unofficial CB channel that does not require a licence, the info is Interesting.

http://www.delboyenterprises.co.uk/446_2...review.htm

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This from a forum theoretically discussing these units
PLEASE NOTE: FOR INFORMATION ONLY - MODIFICATIONS ARE MADE ENTIRELY AT YOUR OWN RISK

Fast becoming popular across Europe is the Unofficial UHF CB System. Working on PMR446 frequencies, but with 4 watts of output power, several handsets are now available for use. One such handset is the Intek MT-5050.
The Intek MT-5050 is a feature packed PMR446 handheld which can easily be modified to give you a full 4 watts of output power and the option of a large range of channels. What's more this modification can be made without the need for data leads and computer software. All you need to do is remove the batteries, then locate and remove the little sticker which reveals 3 wire jumpers.
The radio is supplied as a standard 8 channel 500mw PMR446 radio.
If you only want the higher output power, keeping the standard 8 channels, you only need to cut the link marked 'C'.
Cutting ALL the links will enable 4 watts output power, and additional channels.
The range achieved between two of these handsets can be as much as 20 miles. Some users have also removed the standard antenna and replaced it with an SMA or BNC connector to enable connection to an external antenna.
So to sum up, these little radios allow users to have their very own Unofficial UHF CB system which gives reliable, clear communication over a reasonable distance. There's no wonder they are selling like hot cakes across Europe.