I put up an 80 meter full wave loop using about 280’ of #14 wire in
almost a square. Each end of the loop was soldered to an SO-239
connector. I’m feeding the loop via RG-8 coax, about a 30’ run.

Using an MFJ Antenna Analyzer I can’t find a nice low SWR point. The
lowest I can find is at 2.5 MHz, the SWR at that point is still high at
3.4:1. In the 80 mtr band its 8:1 and in the 40 mtr band its 7:1.

My installation is far from ideal. First, the antenna for about ½ the
loop is at about 20’ high and the second half is about 15’ high. Next,
in the center of the loop is the metal frame work for a screen-room over
the swimming pool (50’ x 30’) which I’m sure interacts with the loop
antenna to some degree. The screening is not metal however the frame
work is.

Of course I can use my MFJ-949 tuner to get a low SWR on any band but by
doing so am I loosing efficiency? I also notice that trying to tune the
loop the tuner seems to be very touchy! I have noticed on 20 meters
the loop received on average about 2 S-Units better than my 20 meter
dipole. On 40 meters it receives almost 1 S-unit better than a 160’
randomwire. On 80 meters just slightly better than a 160’ randomwire.
(all antennas I’m comparing are all at about 20’ high).

I would have started making the loop shorter to bring up the resonate
frequency to 80 meters however I’m concerned as to why the lowest SWR I
can find anywhere on the HF band is still over 3:1. Is it because the
loop low to the ground (20’)? Or do I need a balum? 1:1 balum? 4:1
balum? Looking for any suggestions.

TNX
George – KI4FIA
http://www.MilAirComms.com