[TenTec] Not TT - Wire antenna question.

[Paul]

Hello all, thanks for looking

As folk were discussing wire antennas, please forgive another non T-T specific post!

I have a fair amount of experience with beam antennas on HF / VHF, and colinears on VHF but very little practical experience and know how with wire antennas.

I finally got round to putting up a horizontal loop for HF use.
It is a slightly distorted rectangle at about 23ft AGL, and is supported by 4 fibreglass telescopic fishing rods.
The total length of wire in the loop is 48m or 156ft, the rectangle has 17m sides and 7m ends  
The wire is 1mm diameter with 19 strands.. it's very thin and fireproof, also tough.. I cannot break it with bare hands. Made by RayChem.

The feed arrangements ( don't laugh now! ) are an 8ft long piece of RG58 and terminal block to the middle of a 7m end. I did consider using some 300 ohm twin feeder, but thought that as it is such a short run to the shack that co-ax would do for a test. I have wound 12 turns of the RG58 around a 3/8 inch ferrite rod as an RF choke, this is located right at the feedpoint.
The choke was an afterthought to cure the excess RF in the shack on 80m.
My shack is upstairs, the nearest dirt is 20ft of wire away at least. I have no RF problems with the vertical, but that antenna is about 30ft away from the shack.

The antenna loads up on all HF bands using an MFJ 949e tuner, although it is harder to achieve a good match on 80m.. it seems particularly reactive on 80.
To my surprise, it happily loads up on 160m.. haven't tried calling anyone yet.
Good results on 40m daytime UK signals, most reports said the loop was 10 or more dB better than my Butternut HF6 vertical which is ground mounted with buried radials.
I can see a good dip on a GDO at around 6.8MHz, which agrees with an SWR of 2.5:1 at 7.0MHz as indicated on the ATU metering.

Now for the questions..

Is there anything I can do about the reactivity on 80m?
Should I swap the co-ax for 300 ohm twin feeder?
Would it be worth shortening the loop slightly to bring the natural resonance up to 40m?
Or is there another "magic number" to multiband the loop better?
I like to talk local and work DX, would it be worth adding vertical segments at each corner, running down the 6m long fishing rods?
Or maybe I should consider another form of wire antenna altogether? I picked the loop because I know a few others using them to good effect. I can only really have 1 wire antenna installed at a time.

Any other good ideas welcome, the main bands I want the antenna to be useable on are 160 / 80 / 40m, although 40 and higher are a bonus really.
Any good websites also welcome.

My email address is valid.

A very happy 2004 to all!

Paul MW0CDO.