W3LPL Broad Side End Fire array

There's lots of interest in having the article available on the PVRC homepage.
Here's the text, the three photos referenced in the text are attached.

tks!

73
Frank
W3LPL

My initial implementation of a 160 meter Broad Side - End Fire (BSEF) receiving
array is now in use. Based on initial testing, the 3 dB beam width is about 45
degrees, similar to my 900 foot Beverage and much narrower than my full size
4-square transmitting antenna. The BSEF sidelobes are about 6 to 10 dB better
than the 900 foot Beverage depending on the azimuth and elevation of signals
arriving through the sidelobes. Signal strength is essentially identical to my
900 foot Beverage. The design is based on the BSEF array described on W8JI's
website:

http://www.w8ji.com/small_vertical_arrays.htm

and the implementation of the W5ZN/N4HY 8-circle array described at:


http://www.w5zn.org/files/Design%20Construction%20&%20Evaluation%20of%20the%208%20Circle%20Vertical%20Array%20for%20Low%20Band%20Receiving%20Rev%203A%2002-25-2011.pdf

The first photo shows one of the four 25 foot verticals located at the corners
of a 300 foot by 130 foot rectangle oriented broadside to Europe. Four 25 foot
umbrella wires are attached to the top of each vertical to reduce the impedance
at the base of the vertical. The vertical is mounted on a 1.25 inch diameter
phenolic rod mounted on 24 inches of 1 inch diameter rebar driven into the
ground. The ends of the umbrella wires are terminated in glazed porcelain
insulators. A short piece of light rope attaches the umbrella insulators to the
tops of a seven foot fence posts to avoid deer collisions with the umbrella
wires.

The second photo is the weatherproof enclosure containing the
inductive/resistive matching assembly at the base of each vertical. It consists
of an 18 microhenry molded inductor in series with a 10 microhenry inductor,
then in series with a few turns of wire wound on an Amidon T50-2 powdered iron
toroid. Turns can easily be added or removed from the toroid to set the
resonance of the each vertical to exactly 1840 kHz. A series 36 ohm (approximate
value) resistor provides a 50 ohm resistive match to facilitate alignment by use
of an MFJ-259B Antenna Analyzer, the exact resistor value is selected during
alignment to provide a 50 ohm resistive match. A 25 ohm resistor connects the
the 50 ohm BNC test connector to an F-connector for connection to 225 feet of 75
ohm RG-6 coaxial cable running to the combiner at the center of the array. Eight
70 foot radials are laid on the surface of the ground to stabilize the ground
resistance during both wet and dry soil conditions.

The third photo shows the weatherproof enclosure containing three RF combiners
and a phase inversion transformer. Signals from the two front verticals are
combined by a Minicircuits ZFSC-2-1-75 Splitter. Likewise signals from the two
rear verticals are combined by another ZFSC-2-1-75. A third ZFSC-2-1-75 combines
signals from the front pair of verticals and the rear pair of verticals. The
proper phase relationship between the front and rear pairs of verticals is
provided by the 180 degree phase inversion transformer visible at the right of
the photo and 68 feet of RG-6 coaxial cable. Use of RF combiners for the BSEF
array was suggested by W1MK.