Palomar 95.375' Zeppelin Antenna
Antennas On The Switch
- Palomar 95 (P95) - August -
September 2021: Tested remaining configurations of
antenna length, UNUN mounting height and
counterpoise use, configuration and length.
Settled on a wire 95.375 ft in length with the
UNUN at the top of the 30 foot flag pole,
and no counterpoise. Modeled this
configuration in 4NEC2 and compared it's predicted
performance to observed performance in PSK
Reporter while making hundreds of FT8 QSO's.
For my location with it's restrictions this
antenna length is ideal. In a less
restricted location I think I would investigate
the 200-300 foot antenna length. The MFJ
993b Antenna Tuner has made this configuration
really shine!
ZEP
Antenna Configurations
The Palomar Bullet 9:1 UNUN
connects the 50 ohm coax to a psudo-random length of
antenna wire. I say psudo-random because there
are specific requirements for the length that this
wire should not, and can not be. That would be
any lenght that is resonant on any band the antenna
will be used on. Picking a practical wire
length is non-trivial to operate on
80-40-30-20-17-15-12-10 Meters. In my case
where I am severely constrained, I believe I can get
away with about a 90' horizontal run combined with
the 30' height of the tall flag pole. An 95'
foot wire probably is the longest I can expect to
use at this location. 136', 140.5', 117.5' and
anything over 295' are options, but too long
(maybe).
NOTE: Fall of 2021 - After testing many lengths and
UNUN mounting heights, I have settled on a 95.375
foot wire length with the UNUN at 30 feet AGL.
This will be know as Config 12 and is likely the
final configuration of this HWEF antenna. My
QSL Notes will from October 2021 refer to this
antenna as P95.
The Bullet is rated at 200W FT8
The Bullet UNUN at 30' AGL, no
counterpoise, no guys.
Later I added a guy from the hoisting eye to the
fence in the opposite direction from the antenna
about 30' away. I plan to add another guy to a
flying anchor off the shack's front left corner
(near the 2M antenna) to relieve some of the stress
on the pole.
This is what it looked like at 55 feet.
Apparently I don't have a photo of the full length
95.375 ft antenna yet.
I'll swap out this photo and caption when I do.
Following are notes from each configuration I
tested.
The elements that were modified are the height of the
UNUN, the presence of a counterpoise, and mostly the
length of the antenna wire.
Config 1
Config 2
Moved the Bullet UNUN
to 72" AGL.
I discovered through reading
various antenna manufactures descriptions of
working antenna installations, that the UNUN
doesn't have to be especially far above ground,
and that the antenna wire doesn't have to be
especially straight in any plane.
So for
this configuration I mounted the UNUN at about
5' AGL, ran the antenna wire (55') to the top of
the pole, 30' AGL and then down to 7'.
This shortened my horizontal run 20'.
Config 3
Installed 17'
counterpoise 'under the antenna' at 0' AGL.
In this configration I added a
17' counterpoise to the UNUN, mounted it at 2'
AGL, and ran the 55' antenna wire up and out as
before. Horizontal run about 17'.
During testing of this
configuration, I tried an AM Broadcast "Brick
Wall" filter to reduce the effects of KCID on my
receiver. The filter did EXACTLY what it
advertised. Input signals at AM Broadcast
frequencies were attenuated 40dB. It was
here that I recognized the QRM was coming from
common mode current on the outside of the coax
braid (which was grounded - and that makes zero
difference to RF on a 50' run). The Brick
Wall was returned, and a Palomar Engineers
CMFN-500-50GB filter was installed to decouple RF
on the braid and drain static on the braid.
This made a substantial reduction in KCID
interference at lower HF frequencies, but there is
still more than I want, particularly as the
frequency goes up. By 10M it's
'nasty'.
This is the Palomar CMNF-500-50GB Common Mode
Noise Filter.
I'm injecting 1.4Mhz (KCID's Carrier Frequency)
and comparing to the output. There is no
attenuation.
Config 4
Moved Bullet UNUN to 24" AGL,
added CMNF (Common Mode Noise Filter).
Since I
have about 60' horizontal I wanted to increase
antenna wire length, to increase 'intercepted
RF' - eg: increase sensitivity, so shortly I
will install an 84' #14 THHN wire. The
UNUN will be at 2' AGL and the horizontal run
will be 64'.
Config 5
Config 6
In config 6, I moved the
Bullet UNUN to the top of the pole, and changed
the length to 85 feet.
Here is the config 6 analysis
by MFJ-259B Analyzer
Config 7
Config 8
Config 9, 10, 11
As the notes say, I tried a
bunch of wavelengths. What I was not paying
attention to were the odd harmonic lengths like
5/8 wave or 1-1/2 wave etc. Once I figured
that out, I changed the formulas on the
spreadsheet to account for and then highlight when
a length was over 10% away from resonance and came
up with 95.375 feet - which became Config 12.
Config 12
The "Wire Stretcher" mentioned
above is a little tool I developed to allow
quickly changing the length of the antenna
wire. It is simply a short length of round
bar stock, drilled out to a bit larger than wire
diameter, with a set screw installed at each end
to attach to the antenna. The existing wire
is captured at one end, and a new length added at
the other. This allows a sacrificial wire to
be trimmed, over trimmed, replaced etc.
until the exact antenna length is
determined. In my case, I plan to leave the
Wire Stretcher installed for a couple of seasons
to see how it performs, might be a permanent
fixture.
In this configuration the
Bullet UNUN is at 30' AGL, the 95.375 foot antenna
wire is connected to the fence in a SOUTH
direction by 10' of 550 cord, leaving the bitter
end of the antenna at about 10' AGL with a slight
Easterly (10' in 90') direction.
NOTES:
1. ZEP refers to Zepplin - the German air
ships. Their antennas were trailed long
wires run through similar impedance matching
networks.
2. In my QSO 'Notes' field I list sent and
received signal strength and then add the antenna
and configuration information if you are
interested in a particular QSO please let me know
and I'll respond to you by email.
Possible Future Antennas
The Config 12 while working
quite well in comparison to all other tested
configurations still appears to have limitations
which I want to overcome.
Specifically:
- Central South America
always seem to be out of range. Occasional
QSO in Southern Brazil and Chile, but most of
the times when I can hear them, they can't hear
me. I think this may be due to antennas
departure angle more than anything.
- Antarctica seems totally
out of range, nothing heard ever.
- Africa mostly is out of
range, except on the rare occasion when I can
QSO with stations in the Northwest part.
The current Russian DXpedition to central South
Africa has been heard several times, but
apparently they don't hear me. The
remainder of the entire content is totally quiet
from my point of view.
- Europe, I've had QSO's
along the coast and inland as far as the Urals
on a couple of rare occasions. Same for
the UK and Greenland. Seems that's my
limit in the Easterly direction. I want to
'light up' Russia and the Balkin states
better. Same goes for Italy, I can
occasionally get there, but going any farther to
the East never happens.
- Asia, going the other way,
I can get into Japan very easily, occasionally
China, North Western to Southern Australia and
New Zealand are reachable, but further toward
the West is once again out of reach.
There appear to be two ways I
can overcome these limitations, one is to wait
patiently for Solar Cycle 25 to mature and hope
that fixes the problem, or I can explore antennas
demonstrating lower radiation angles, and possibly
controllable horizontal gain which fit within my
limited space. To that end, I am looking at
vertical dipoles which need no ground plane.
Before I either build or buy one, I'm going to
model a few and see what their far field radiation
patterns look like. I've got this crazy
notion that I might be able to erect a temporary
reflector or director that I could move around to
steer the signal a bit ... that could be
'fun'. Unfortunately I don't believe I have
sufficient room to setup two verticals to be phase
controlled. If I could do that, I might be
able to overcome some of those limitations ...
A new option appeared today -
the MFJ-1026, Deluxe, Noise Cancel / Enhancer /
Antenna - wow! What a mouth full. This unit
uses a sense antenna to create a variable phase
relationship between an interfering signal and the
passband of the receiver. It can tune out
strong signals such as single frequencies adjacent
to the desired signal, or broadband noise that
appears as a 'picket fence' in the spectrum
waterfall. Now my plan is to build a wave
trap for KCID and also obtain the MFJ-1026 to
silence the din of all the LED's, WIFI's, Routers
etc. in the park around me. I think the 1026
is going to be a game changer, and it could be
used by its self to sink KCID, but I want
flexibility to zap QRM from lots of sources so I
can scan the bands for SSB (which I simply can not
hear above the very high noise (about S9+13 or
more).
Update Late December 2021 -
The MFJ-1026 has proven to be a bit difficult to
use in the way I had anticipated, mostly because
it's sense antenna wants to be 'similar' to the
big honking transmit and receive antenna, which is
horizontally polarized and 95 ft long. Some
good has come from mucking about with the unit
however. I have added ferrite toroidal chokes to the DC power,
USB, and RF connections to the radio, and a Morgan
Systems M-400X Broadcast Band Filter. Now
the QRM is much, much lower, and I have also
identified a signal that I thought was IMD
(Inter-modulation Distortion) as an artifact of my
small and inexpensive computer monitors which I
use for the radio control computer. These
are very discrete frequencies which form a wide
band 'comb' pattern. I've put ferrites on
every input and output of the monitor without
affecting them, which means they probably are
radiating through the screen or direct from their
point of origin with the monitor. I
don't have the space to try separation except as a
last resort for testing only. At this point
these signals are not very strong, and do not
interfere very much, although I would like to
eliminate them.
Recently I have been thinking
about the 'departure angle' from my P95
antenna. The 4NEC2 antenna modeling software
suggests:
NOTE: departure angles are
referenced to 0 at Z (straight up) and 90 at XY
(horizontal). Find the complimentary angle
to describe take off angle in conventional
terms.
80M departure angle at -10
degrees with a beam width of 90 degrees, meaning
it puts most of its energy up to the North (a
mostly useless direction from here) at NVIS
angles.
40M departure is -35 degrees
with a beam width of 100 degrees, again to the
North.
30M is at +45 degrees with a
45 degree beam width and 2.49db gain. Now we
are getting somewhere! South and at least
some of the energy is getting down low enough to
skip.
20M has a primary at -60
degrees 30 degrees wide, at 2.21dB, and a
secondary at +50 degrees, a little broader, and
not quite as strong. This is the one that
hits South America so well, but in the direction
of Europe (East), in both planes it is around
-12dB.
17M primary is at -65 degrees
30 degrees wide, at 1.99dB. Secondary at +50
degrees 35 degrees wide, nearly as strong.
15M primary is at +70 degrees,
25 degrees wide, at 3.33dB. Secondary is at
-50 degrees nearly 60 degrees wide at about
0dB. Its Horizontal component is strong at
+90 (South) about 60 degrees wide, and very weak
at -90 (North) and bifurcated.
12M primary is at +75 degrees,
20 degrees wide, at 2.62dB. In the
horizontal plane the beam is about 80 degrees wide
and centered just about 5 degrees East of South.
10M primary is at +75 degrees,
15 degrees wide, at 1.53 dB. In the
horizontal plane the beam is about 60 degrees wide
and centered just about 5 degrees East of South.
6M primary is at +80 degrees,
10 degrees wide, at 3.24 dB. In the
horizontal plane the beam is about 40 degrees wide
and centered just about 5 degrees East of South.
Modeling vertically stacked
dipole antennas at various heights above ground
level (AGL) for comparison:
20M H=20' AGL departure is +/-
75 degrees, 20 degrees wide (each), with symmetric
secondaries at +/- 40 degrees only about 1-2 dB
weaker. The good news is this pattern is
completely round in the horizontal plane.
20M H=5' AGL departure is +/-
75 degrees, 25 degrees wide (each), with no
secondaries, front to back is 0.77dB, and the
horizontal plane again is perfectly round.
Moving the antenna toward ground has flattened the
vertical significantly!
20M H=0' AGL departure is +/-
70 degrees, 30 degrees wide (each), with no
secondaries, but the vertical is 'fuller' toward
30-45 degrees reducing the available power at the
primary so this rates -2.0 db. Again the
horizontal is very round.
NOTE: Placing stacked
vertical half wave dipole so that the end of the
bottom element is between 0' and 5' AGL produces a
slightly better pattern for DX than setting the
antenna higher. I have not optimized for
height AGL.
Synopsis:
The 95.375' sloper with the
UNUN at 30' AGL develops very different patters on
each band. It seems to be a very good
antenna 20M and up, but signal reports seem to
indicate that not much energy is arriving
downrange and it seems to be prone to dead zones
that are persistent.
The stacked half wave dipole
(SHWD) will have only its lowest frequency element
at a height that is significant to ground. I
believe 80M is the lowest band I want to try to
utilize on this antenna, and each subsequently
higher band dipole will be mounted somewhere up
the antenna, and probably will not share a center
point, thus it seams reasonable to accept the
models of individual vertical half wave dipoles as
indicative of performance when attached within a
foot or less of the radiating element(s) of the
lower band antennas.
Where the 80M P95 is -10/90
(angle from vertical/beam width), the SHWD should
be -75/20 or close to that number, as all of the
modeled SHWD antennas are quite similar once they
are over 10' AGL. It is anticipated that the
antenna's driven elements will not act as
reflectors, or directors for the other elements
because they will be quite close to each other.
I think I have pretty much
talked myself into building or buying a multi-band
vertical.
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