Topband: DHDL

Grant Saviers grants2 at
Sun Jun 30 13:41:41 EDT 2019

That statement doesn't agree with my quick modeling (I also wondered why 
my 40' base had some observed benefit on high bands now and then).  Both 
a 60' for 160 and 40' for 80/40 worked fine.

for a 60' baseline, 6' Z bottom wire, 30' Z to top or about 190' of wire:

Freq Gain dbi F/B db peak ang

1.8   -31     12     20
3.5   -16     15     25
7.0   -4      9      30
10  elliptical broadside about 5 to 10db F/S, 25 deg elev
 >14   spikey pattern broadside and low vertical gain, maybe not useful

EZNEC 4.2 over average soil.  With higher conductivity soil, F/B 
improves a lot, and gain a few db.  Patterns are about the same.

Grant KZ1W

On 6/30/2019 9:03 AM, Martin wrote:
> Topbanders,
> just read a few articles about DHDL antennas. One article states, the 
> cut off frequency where the antenna becomes useless is when the overall 
> length of wire reaches a 1/4WL. In my understanding the original 
> dimensions , 2*7.5m vertical plus 22m horizontal plus 2*13.3m sloping 
> wires equals 63meters, which is already a lot longer than 1/4WL on 160m. 
> What did i miss?

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