Topband: NEW RX HWF antenna report Spring to Fall

Tue Dec 22 09:32:46 PST 2009

Hi low band lovers. This is a long report.

I would like to share with you my experiences using horizontal loops on low
bands.

Last year during the winter I struggle to copy signals from south Asia,
9M2AX heard me on top band quite well and I was not able to copy him on 160
and not even on 80m, my BWF, Big Waller Flag even with a very good RDF and
excellent nulls on the sides and on the back (over 30 db deep) it was not
enough to pull weak signals from my city lot suburban noise floor on long
path.

As a last resource I decided to test one dual phased flag in the horizontal
position on top of my TX tower at 116ft high, The HWF was born with 40 ft
boom holding two horizontal loops 16ft x 13ft. 

Miracle happened, at the very first day using the new HWF I was able to hear
9M2AX on 80m, Q5, 559 and others decent signals. Not only that but the
performance on 80 m was astonished, I could hear Europeans in the middle of
the afternoon on 80m Q5 every day during the winter same on 40m and 30 m.

The new HWF works like a polarization filter, the HWF vertical pattern has a
deep null on the front lobe over 20 db attenuation on all vertical signals,
so the signal ration between horizontal signals and vertical signals is well
above 30 db. The first thing I noticed right away was the immunity to
receive power line noise or man made noise; the HWF noise floor is 20 to 30
db quiet them the VWF (vertical WF). 

The HWF -3db point is around 17 degree. The horizontal signals are 10 to 15
db weaker then vertical signals on 160 m, the final result was a clear copy
on signals as never before experienced from my QTH. 

How much horizontal signal I could expect on 160 m with a phased loop at
116ft?  

That was my big question, however during the last 10 month, it worth a very
minute I spent on this project. I keep a record on signal at noise level
that I could copy only with one antenna, the Horizontal WF was able to pull
signal out of the noise 80% of the time, and the Vertical WF only 20% of the
time.

I worked 12 new countries on 160m this year because I was able to hear them
only with the HWF (FW5RE, V5/DJ4SO, JD1BMN, FR5DN, 7P8MM, TO7RJ, TX5SPA,
ZY0T, YJ0CCC, XR0V, 5N0OCH and VP8BUG).

Zone 18, 19 and 17 was also good most of the time on 160m; however near the
equinox I noticed lack of horizontal signals for several weeks.

Another important fact was a new buzz due north of me, very strong s9 with
200 Hz BW on cw, this buzz made my VWF useless due north for almost 4 month,
I’m very happy today because FP&L just fixed it this morning. So the only
antenna I’ve been using is the HWF so far.

On 80m the performance of the HWF is close to a miracle, I can hear like a 4
elements full size yagi. LP on 80m is easy as pie to copy south Asia. 

The performance on 160 m is not the same as 80m, so I modified the loops
increasing them to 24ft x 13ft, the performance increased a lot with a
bigger loop.

NX4D also upgrade his WF to a Big WF, 50ft boom and 24ft x 204 ft loops, he
just worked JT1CO on top band, and now Doug can hear every weak signal as
good as most of the big guns in topband. 

Based on the experience using the HWF I suggested PY1RO to try a single
horizontal flag, Rolf is living in a small city lot with huge power line
noise, he was going QRT,  Rolf was using a ¼ vertical on 40m, and he was
able to hear  nobody with s9++ of power line noise,

The single loop HWF is a square loop 16ft x 16ft, symmetrical, with one
trafo 3:1 on one side and a 1000 ohm resistor on the other side, like a
flag.  The feed line MUST be twisted pair, I removed one pair from a
Ethernet CAT 6 cable, one twisted pair has 100 ohms and very low
attenuation, At the end of the line , very close to the radio there is a
100/50 balun, (5t/7t) . 

On all HF bands the noise went from s9++ to s0 and the signals without any
preamp were Q5, crystal clear like VHF. On the second day Rolf was ale to
copy K4M on the afternoon, 3 hours before PY1Ro sunset. Rolf worked 150
countries on the first 3 month using only 100w, before the HWF he was able
to work only 3.

Now Rolf instead of QRT he went QRO, his 3-1000Z is back in business again.
I hope Rolf can find a solution for his TX antenna and get back to top band
where he belongs.

There are few records WAV you can check on PY1RO blog at the end , one wav
file is SSB in Portuguese but you can clearly see the comparison between the
horizontal loop and the vertical the other 2 are CW. A65BE and LZ2VU.

http://riodxgroup.dxwatch.com/node/301

There are 2 photos as well so you can see how simple this antenna is.

Before you drawn conclusions, the best performance on 40 m and bellow, is
with a 16ft x 16ft at minimum 24 ft high,  for 80 m I recommend 20ft x 20 ft
at 50 ft high and for 160m 24ft x 24 ft at 80ft minimum high. .

Here what you need to know, use only twisted pair, NO COAX CABLE. The big
issue with common mode noise is that it does not exist on twisted pair. If
you want to use coax you need brutal force chokes, (5K or more) and know
what you are doing.

One single horizontal flag has a decent front back but a very wide front
lobe around 120 degree, it is useful quite good up to 180 degree.  The best
solution is a dual phase flag, HWF rotatable, it has RDF close to 11.5 db.

I’m planning to present a full report on my HWF after the winter DX season,
it is necessary to test a receiver antenna for at least one full year to
understand how it performs, some times I can hear nothing on the HWF for
weeks, QSB is another interesting factor, the signal just move from V to H
most of the time we see QSB on 160m,.

I thing the HWF deserves more attention and development. I’m mechanically
limited on my tower at 116 ft and the size of my HWF, 40 ft boom and 24 ft
elements, the same size of a long John 4 elements yagi for 15m, I’m sure
bigger is better may be 32 ft elements and 50 ft boon at 120 ft high, or
more!! 

I will update my site next sprint with the final report on my HWF
experiments.

Good DX 

Jose Carlos 

N4IS