[Antennaware] Height for horizontal loops
Terry Conboy
n6ry at arrl.net
Fri Sep 25 13:01:06 PDT 2009
Thanks for the modeling data, Paul. Not surprisingly, the horizontal
loop (1 wl circumference) has to be higher than a dipole to give equal
or greater gain at angles 50 degrees or less (since the loop in free
space has a little more gain straight up than on the horizon). On the
harmonic bands, the comparison gets messy - a dipole also has some high
gain lobes when operated at frequencies where it is longer than 1/2 wl.
73, Terry N6RY
On 2009-09-24 4:20 PM, Paul Decker wrote:
> Of course, higher seems to be better, and bigger also seems to be better to some extent.
> This might be sensory overload, but it does demonstrate what loop size and height can do to/for the loop.
> I did some modeling on this a while back over average ground, which seems better than what I have:
>
> 80 meter dipole at:
> 15 feet has - 0.22 dBi @ 50 deg, -1.53 @ 40, -3.47 @ 30, -6.52 @ 20, -12.15 @ 10 deg
> 30 feet has 3.78 dBi @ 50 deg, 2.57 @ 40, 0.73 @ 30, -2.24 @ 20, -7.83 @ 10 deg
> 60 feet has 5.81 dBi @ 50 deg, 5.01 @ 40, 3.53 @ 30, 0.86 @ 20, -4.54 @ 10 deg
> 120 feet has 5.29 dBi @ 50 deg, 6.66 @ 40, 6.9 @ 30, 5.47 @ 20, 0.82 @ 10 deg
> 180 feet has -10.64 dBi @ 50 deg, 1.38 @ 40, 6.86 @ 30, 8.04 @ 20, 4.72 @ 10 deg
>
> a full wave 80 meter horizontal loop at:
> 15 feet has -0.67 dBi @ 50 deg, -2.47 @ 40, -4.9 @ 30, -8.35 @ 20, -14.26 @ 10 deg
> 30 feet has 2.94 dBi @ 50 deg, 1.54 @ 40, -0.79 @ 30, -4.17 @ 20, -10.03 @ 10 deg
> 60 feet has 5.31 dBi @ 50 deg, 4.03 @ 40, 2.08 @ 30, -1.00 @ 20, -6.65 @ 10 deg
> 120 feet has 5.14 dBi @ 50 deg, 6.03 @ 40, 5.8 @ 30, 3.96 @ 20, -0.9 5 @ 10 deg
> 180 feet has -10.66 dBi @ 50 deg, 0.87 @ 40, 5.88 @ 30, 6.65 @ 20, 3.06 @ 10 deg
>
> three full waves on 80 meters, horizontal loop at:
> (NOTE: pattern has "gain" lobes at different take off angles need to point to right directions)
> 60 feet has 6.58 dBi @ 50 deg, 6.73 @ 40, 5.55 @ 30, 2.81 @ 20, -2.68 @ 10 deg
> 120 feet has 5. 4 dBi @ 50 deg, 7.72 @ 40, 8.25 @ 30, 6.73 @ 20, 1.91 @ 10 deg
> 180 feet has -10.33 dBi @ 50 deg, 2.5 @ 40, 8.3 @ 30, 9.41 @ 20, 5.93 @ 10 deg
>
> using same 3x loop on 20 meters:
> 60 feet has 12.97 dBi @ 14.0 deg
> 120 feet has 9.01 @ 23 deg, 14.4 @ 8 deg
> 180 feet has 6.2 dBi @ 27 deg, 12.55 @ 17 deg, 14.6 @ 5 deg
>
> You can see that using the extremely large loop on the higher frequiencies has some serious advantages. The pattern isn't clean, but if the lobes are pointed in a direction you want, bonus!
>
> hope this is a little useful anyway,
> 73,
> Paul (KG7HF)
>
> From: John Geiger <aa5jg at yahoo.com>
> Subject: [Antennaware] Height for horizontal loops
>
> How high does a horizontal loop (the look skywire) need to be for decent performance? A quick google search revealed that people were running them at 25 or 30 feet with good results (in their opinion). I know that high is better, but how high does it need to be to show real improvement over a dipole?
>
> 73s John AA5JG
>
>
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