Horizontal FM section

WHY Horizontal FM?

Why use horizontal when most of us are using vertical antennas for FM working?

For me it was out of curiosity, and why not? there are others who also use Horizontal FM on a regular basis. I mounted the beam in the horizontal plane specifically to see if there was any increase in signal strengths on the band at all. Well I was very dissapointed at the results, I thought that having so many elements I would have seen better signals from vertical stations which had medium signals before, not so. There was only one station which improved: GB3MP. All other stations were well down, not stopping there I tried several CQ calls on S20 with only local stations replying to me (within 20 miles).

The band was very quiet! Then out of the blue I heard M0FGH calling CQ, I did not recognise his call sign so looked him up using QRZ.com and the southern accent became more apparent, he was in Kent. I was using a borrowed radio at the time with about 35W output, I gave him a shout, he came straight back to me.

I spoke to Steve about the antenna I was using and the power that I was using, and he said that he was only running about 30W but into two 9 element tonna beams horizontally polarised. I couldnt but help notice that the signals received from Steve were very unusuall, looking at the strength of his signals, they were all over the place, looking like what spradic E would look like, flutter I think the word is, and multipath, but it is infact Tropo Scatter which made the contact possible I think?, and it does seem to be there all the time. After a good chinwag with Steve that lasted a good half hour with only flutter and slight QSB, I was quite amazed at how the signals got here when there wasnt a lift, well I didnt hear any repeaters, or the usuall stations I would hear in Birmingham and the like even on the vertical antenna. I was hooked.

I must admit there are not very many Horizontal users that go to S20, mostly they work SSB, but on the odd occasion some will come to S20 and give a call or two. You can often tell the distant stations from the local stations due to the flutter on their signals, almost like they are mobile stations. I have worked quite a few horizontal FM stations now since June 2005.

I have worked one SOTA station on horizontal FM, but he wasnt a local station, he was using a quarter wave dipole when he was on Garth hill, in Cardiff. I dont hear many SOTA stations using horizontal FM in any areas regulary. I have worked some SOTA stations on as little as 20Mw when both working on beams, not even local stations can hear me properly then, h.i.

Though I have worked stations in Spain and Italy on SpradicE, and stations in France on Tropo. My best enjoyment sofar is PE1AHX on FM in flat conditions, though a signal report wasnt given, we both got our callsigns in the log. Troposcatter? is there all the time as far as I can tell, some days are better than others, November and December seem to be very low, though we have had a good lift at the beginning of December, that isnt quite what I am looking for, but I do enjoy working tropo inversions and local lift condtioins, as do all stations working vertical do too, I guess.

What type of antennas should you use?

A very good question, and at the end of the day, an antenna of high gain would be the better choice over a non gain antenna like the:

Halo - Loop - Dipole -

All the above antennas are very good, when I have used them, I have heard the two major beacons on two meters, GB3ANG and GB3VHF while sitting here in the shack holding the antennas in my hand. Thou all of the above antennas are slightly directional so getting them in a direction thats good for you would be a good working point for you, though, I have come accross another antenna I have not seen before until June 2006, they call it an "Omniangle", the manufacturer will not sell outside the US. Quote :

Unfortunately, we do not sell our Omniangle series outside N America.
The matchbox is quite sophisticated and we do not share that information.

I think the Matchbox is a "Capacitor Inductor Network" that converts the feedpoint from 10 + j90 to 50 ohms, there also a teflon current mode balun (for link - see here), well big long names mean it will probably be something very simple to home brew if you know what a Capacitor Inductor Network is. The antenna is also 30% longer than a conventional Loop or Halo, that one of the reasons for the transformer, as the antenna is no longer resonant at 144mhz.

The Omniangle would appear to be a very good choice in antenna because it isnt directional and should be best for all round coverage, stacking two of these should be a good idea, as having more gain is a good thing.

Though using a beam would be best as all your power pointing in the direction you want it. Bigger the gain the better, but bigger the gain sharper and more accurate you have to be to point at the station you want. Long booms and wide spaced yagis are the thing to go for, with gain figures over 10db would be best.

Perhaps a good beam and a Halo/Loop/Omniagle would be a good choice to have at the station setup, so that you dont miss that other station calling from the side of the beam that you cant hear. Or for SWL I think the Omni Directional Horizontal Polarized antennas are good for either SSB or FM if you dont have the dosh for a beam and rotator.

 

How many of you have an FM only radio for VHF & UHF?

Am not realy interested in stations that mainly use HF unless you have a genuine interest/enjoyment  of "DX" on VHF/UHF bands.

However, If you feel that you would like to work stations outside your normal working circle on VHF/UHF, but feel you cant "DX" because your radio only has FM, and you dont have a monster beam, or a big linear, I would realy like to hear from you, no matter where you are in the UK, especially if your a M3 licence holder or perhaps you want to try and broaden your understanding in another area.

The only rules are:

You need to be a licensed Radio Amateur with a VHF/UHF FM radio, have at least a Dipole/Halo or "S.O.T.A" Beam type antenna (3 or more elements), patience (lots of it) and determination.

. email me for more info

 

 

Various recordings on FM

At the top right of the page are some recordings I have made, one was G0VHS in Weymouth, we conducted a SSB and FM test, the results for me are very important in my search for understanding certain types of propagation. Which do you think will come out as the best? Though, (I did note that when signals were below the FM threshold *just above the noise level, SSB was the one which came through), even though the audio was very low - with headphones (without preamp) you can still get messages through - tiring it maybe. .

 

Various Screen dumps of the recordings

Click on images to play audio

This is a recording of Terry just after the FM test, FM was too weak to work at that point, but SSB was just workable, I think that this maybe Tropo Scatter, however, when the signal is higher than S1, that could be Tropo (I think). I will have to work Terry again and see if we can work eachother anyday, if this is so, tropo scatter would be the form of propagation if the signals are constantly weak at close to noise floor, if FM is steady and strong, that to me would indicate tropo? I will hopefully replacing the old RG213 coax with some Ecoflex15 soon, maybe the troposcatter noise floor will be lower in relation to the signals.

 

 

 

 

Recording of G0VHS talking in SSB mode then changing over to FM mode and back again. The graph of the audio recording may not mean that much, but as conditions were changing all the time, more recordings are apparent.

 

 

 

 

 

 

This is Craig MW0MXT in Llanelli on SSB and switching to FM, though Craig says that my SSB audio was louder than on FM to him, I am now wondering if I change radio the results will be the same?

Though you can see from the graph that FM is far louder received through the FT726r

 

 

 

This is a recording of GB3VHF (Kent beacon - 144.430).

3 minutes duration. Receive mode was FM so that you can hear the fading. There is a very unusual noise near the middle of the recording.

This is Tropo. an example of Tropo Scatter using GB3VHF will be placed here soon.

 

 

 

This is a recent recording of Kevin 2E1KJB in IO90IS, he asked me for a FM test, I thought that because he was so weak on SSB that it would fail. Listen to the recording and see how he did, there is no recording of myself as the recording is direct from the FT726R audio out at the back of the radio.