Topband: HWF two years report. N4IS

[n4is]

Hi Top-Band lovers

 

It has been two years since I started my experiments with Horizontal Waller
Flag.  I sent a report like this a year ago with great results, however
after another year developing this incredible antenna I have some new and
important things to share with the group. 

 

My big surprise is the RX improvement with the new propagation scenario we
have today, the upward movement of the solar cycle has been full of
surprises. 

 

1-      Let me first redefine the Horizontal Waller Flag to make it easy to
understand it. The HWF is indeed a noise canceling antenna. The two loops
are phased 180 degree, it means the Vout = Va-Vb, the loops must be
symmetrical as possible. For any signal arriving at the same time on the two
loops Vout=0 (zero), nill, nada. That's right! No signal from high angle at
all, from up or from the sides, because the cardioid diagram of the
terminated loop also called Flag, there is a very good front back. Looking
at the 3D patter it is easy to see a deep attenuation of vertical polarized
signal; the attenuation for vertical signals varies from -40db at the front
lobe to -15 db on the side lobe at 45 degree elevation. The front gains is
also low as -43db and the vertical gains is below -80db, this put the
vertical signals way below the noise floor of the receiver. You just can't
hear it.

 

a.       As a result the characteristic described above the HWF has almost
no response for any vertical signal including all man made noise, including
power line noise, plasma TV noise, street lights etc. I'm using a new 40 db
gain preamp with 0.7 db NF. During the day with no QRN when I connect the
HWF at the preamp the noise floor increase only 0.3 dBm. Anything more than
0.5 db is a clear indication the HWF has some kind of problems.

 

b.      Different material is a big problem, My HWF is all aluminum and any
joint with different material can generate noise. I used to have a wire
terminal on an aluminum wire to close the loops at the tip of the aluminum
elements; this joint generates a lot of noise like precipitation noise. All
the noise was gone 4 month ago when I changed the way I connect the aluminum
wire with the aluminum tube, now I have aluminum against aluminum and the
bolt press them together, and all protect with liquid tape to avoid any
moisture.  (Thanks to Larry W8VVG for this solution on his WF).For new
antennas I recommend using fiberglass elements and regular copper wire for
the loop, aluminum is a high maintenance solution. If I need to fix this
issue again I'll replace the aluminum elements by Fiberglas. 

 

c.       Interaction with TX antenna is expected, My HWF is also the top hat
of my TX vertical. (High isolation between the loop and the boom is
necessary). My TX antenna has a skirt to detune the TX vertical during RX,
when I remove the detuning by grounding the skirt the noise on my HWF
increase only 0.5 dBm.  Any problem with the loop results in great increase
in noise, When I see 20dBm increase something is wrong, like a bad
transformer damaged by lightening or the aluminum wire broke with the wind
and one loop is open.

 

There is no comparison between the HWF and a horizontal dipole or inverted
V. They are different antennas and here are the differences.

 

a-      The dipole TOA is straight up 90 degree, the HWF TOS is 36 degree at
116 Ft high and the HWF cancels all signals coming straight up. To lower a
dipole TOA to 36 degree the antenna need to be at 300 Ft high and only a
dipole eliminates the 90 degree lobe,

 

b-      The dipole is horizontal, but the horizontal gain is max at the
broad side, everybody knows the 8 shape of the dipole however the dipole has
another 8 shape for vertical gain along the wire, so the dipole receives
vertical signal along the wire like a beverage does. The dipole or the
inverted V does not cancel vertical noise. Both horizontal and vertical
field makes a dipole total field no directional.

 

c-       The HWF has great directivity, RDF is close to 12 db and I can turn
in all directions. The dipole is no directional.

 

Anther very important development I the use of very low noise high gain
preamplifier with sub 1db NF. This preamp is still under development but I
can provide information for everyone that wants to help to improve it or
experiment with this new preamp.

 

The band has been increasable noisy demanding quiet RX antennas as never
before, I hope to motivate more people to test and develop this new idea

 

Regards

Jose Carlos

N4IS