Sorry everyone, but I heed a bit of advice
Ive got a few home brew antennas, but I arrived at a site I was camping at and said do you mind if I gone on air and the guy to my surprise said, blimey that's interesting go for it.... Trouble was no trees.
So I took my 10m mast, which usually supports my end fed UK Antennas Multiband wire and its 39m wire and grabbed some tape and the 39m long long wire, I woujd 29 metres in the middle of it round a piece of old circular gutter I found and put the rest up my glass fibre pole. To my astonishment I was at it all day all over Europe and beyond into Russia, Azores, West Coast on 20, Inter Europe on 40 and Spain on 10m and another good one on 17 I could hear Alaska and Kuwait on a pile up.... But not chance to break with my meagre output and setup...
But it would not work at all on 80 locally, they could just hear my though I could hear them well.
What have I made? How can I make it better, Centre loaded end fed vertical? Can I use a capcitance hat.
It tunes up readily or my portable manual tuner on all bands down to 1.1 not too much on a knife edge...
Is the centre load actually too tight.?... What would happen if it was more loosely wound or more loosely wound on a longer smaller diameter tube, perhaps from lower down?
Do you think I couldn't model this hair brain nonsense on that software?
So much to learn about the best bit.... Antennas.
Mental Portable Antenna - actually sort of works - can I make it better?
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2E0JFS
- Regular
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- Joined: 20 Feb 2011, 17:25
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InTheClouds
- Super Member
- Posts: 232
- Joined: 15 Mar 2020, 15:36
Re: Mental Portable Antenna - actually sort of works - can I make it better?
Sounds like you had a lot of fun there....a bit difficult to visual what you made from what you wrote.. but assuming it is a centre loaded vertical then loosening the coils will reduce the inductance of the coil and tightening them will increase it. However that will have a different effect on the loading for each different band.
On 80m ground wave/line of sight it would be a bit inefficient (coil) and vertically polarized, where locals would likely be horizontal... there you can lose 18dBin cross polarization losses. You probably made a loaded 1/4 wave and that would work rather poorly without radials. This would explain the poor performance.
I suspect that playing with the coil will improve and worsen dependent on band and if your internal ATU is doing the business anyway (same thing as messing with the coil really) then why bother, what you may gain on one band you will lose on another.
What you may try is to make it load without the ATU on the band you work the most... then tune it with ATU for others.
What is most likely to make the antenna work even better is a bunch of ground radials to the edge of your effort threshold. Generally the more the merrier.
On 80m ground wave/line of sight it would be a bit inefficient (coil) and vertically polarized, where locals would likely be horizontal... there you can lose 18dBin cross polarization losses. You probably made a loaded 1/4 wave and that would work rather poorly without radials. This would explain the poor performance.
I suspect that playing with the coil will improve and worsen dependent on band and if your internal ATU is doing the business anyway (same thing as messing with the coil really) then why bother, what you may gain on one band you will lose on another.
What you may try is to make it load without the ATU on the band you work the most... then tune it with ATU for others.
What is most likely to make the antenna work even better is a bunch of ground radials to the edge of your effort threshold. Generally the more the merrier.