Wednesday, September 21, 2016

Big back yard loop antenna gives low noise and excellent transmission

In Amateur Radio experimenting with antennas provides some of the most interesting results for the least amount of money, particularly if you mess around with wire antennas. Improvements to the antenna provide much greater benefits than money spent on transmitters or amplifiers.

In recent months I've been using a doublet hung from a gum tree fed with open wire feed line. To make it work on 80m I extended the ends in a "dog legs" back along the side fence lines. This arrangement works on 80m, 40m and 20m. While there are good reports of my transmission, reception has been very noisy, particularly on 80m.

This week I turned it in to a big loop by closing the ends and hanging them from the house.




It tunes up easily on 80m and 20m and with a little difficulty on 40m. Yesterday I did a lot of tuning around and listening and experienced very low noise with big signals. Today, I had a test QSO with Patrick, VK2PN who reported excellent signals from me, especially on 40m.

More detail: The loop is simple figure eight lamp flex (half) roughly joined with knots and screw terminals - this can be improved. 450 ohm slotted feeder runs down to the shed and is terminated with a 4:1 balun before the rig's auto-tuner.

4 comments:

PE4BAS, Bas said...

Hello Mark, I've been using a loop for years and only setting it up in winter. It is a excellent performer on 80,60 and 40m. Especially for NVIS but DX is no problem as well. At the start of the year I worked 100 countries in only 79 days with a power of just 5W with it. When using it on WSPR I always end high in the PE1ITR WSPR challenge (receiving) list, a prove that the loop has less noise then any other antenna. 73, Bas

Peter Marks said...

Thanks Bas,

Yes I'm really impressed so far. The WSPR Challenge is a great site. I love the idea of competing on reception. I do well in the distance competition.

73

Peter

vk1nam said...

Hi Peter, can you please expand on the feed point arrangement? I use a 20m loop for 14 MHz through to 52 MHz. The feed arrangement is 450 ohm ladder line tuned in the shack with a homebrew Z Match. I have space for a 40m loop and plan to feed the loop with a 4:1 balun.

Thanks
Andrew, VK1AD

Peter Marks said...

Sure Andrew. The loop is simple figure eight lamp flex (half) roughly joined with knots and screw terminals - this can be improved. 450 ohm slotted feeder runs down to the shed and is terminated with a 4:1 balun before the rig's auto-tuner.

The balun works for me although I can't get it to tune on 6m