ANY ADVANTAGE TO INCREASING LOOP SIZE?

[ve6pg]

..hi from tim...i was wondering if there might be any advantage to increasing the size of my 160m loop...it is 540ft, at about 60ft. fed with hb open wire ladder line..it works fine, and i use it on 160, 75, 40 etc.  the thing is, i have the room to add to it, so that it would be 1.5, 1.75 wavelengths on 160. this would have the thing 3 wavelengths on 75. would this be a good thing, or at some point it would be an exercise in wasted time, effort, etc...

..tnx..

..tim..

..sk..

[K1JJ]

Not really, Tim.

You could model it and see for yourself, but after a full wave loop length, the pattern starts to turn into unusable, multiple lobes with deeper nulls.   It would seem logical that more wire in the air is a good thing, but it must be carefully put in phase to become additive and show gain. Multi-wavelength loops are not a good way to phase wire for controlled directional gain.

If you are looking for gain and obviously have the room, put up a pair of phased, driven dipoles and rule the whirl..

T

[ka3zlr]

The W8JK Phased array comes to mind
I built one once it werks well..

73

Jack.

[K5UJ]

Tim, my opinion which is worth as much as free is, is that your loop on 160 at 60 feet is like a loop 80 at 30 feet and a loop on 40 at 15 feet.  think about it.  would you put up a horizontal wire antenna (any type, loop dipole ...) for 40 m. only 15 feet high?
At that fraction of w/l phasing etc. may not even work very well.

The point is 60 feet may seem high but not in terms of wavelength.  There is significant ground loss due to coupling to ground.  I know the NVIS guys all think that height is okay but they get their data from the military.   The flaw in their work is the military: A.  wants a single NVIS antenna on multiple frequencies and B. the military can run 10 or 20 KW and they don't care about ground loss and don't bother to work it out.

My experience has been that there is about 10 dB difference on 75 between 25 feet and 50 feet with a horizontal dipole.  that's 50 and 100 feet on 160.  Also the loop has twice the area if you will of a dipole which increases coupling to ground.   Bottom line, and I know a lot of guys with horizontal wire antennas on 160 don't like to hear this, if you can't get a dipole up to at least 100 feet then put up a vertical that is working against ground i.e. an inverted L, T or straight up quarter wave over 60 radials.
Run the loop on 75 and it might even be better with a length of around 275 feet for 75 and 40.

Rob

[flintstone mop]

I'll have to agree with Rob,
Some folks think when they're past 40 feet that they have arrived have passed the lowley small lot dweller.
Horiz antennas are all cloud warmers at our typical Ham operator heights until you get to 20 M. Then it gets easy and THEN you will have a directional antenna.
My 5 Pesos worth.

Fred