New 160 meter broadside/endfire array
WW2Y and K2WI made this rectangular antenna popular on Top Band from New Jersey in the 1990s. The basic
description is in the ARRL Antenna Book and ON4UN's book Low Band Antennas. It was developed further at VY2ZM (K1ZM) around 2000.
My version, still a work in progress, borrows from their ideas. Mine uses wire elements hung from
existing towers and trees. Like the one at VY2ZM, mine uses broadside spacing of about 5/8 wave for maximum gain. I had one
T element available from an existing parasitic array, so other elements will be the same size. The T is 73 feet vertical and has a top hat of 58 feet, resonating
around 1930 kHz. A small coil at the base brings it to resonance at 1820 kHz. Each element will have 120 radials about 1/4
wave long. The radial field will be slightly irregular due to drainage ditches interceding and property limits.
Element 1 is the original from the existing parasitic array and hangs from a catenary strung between two
towers.
Element 2 is supported by another tower that had been an 80-meter vertical. The 64-feet of Rohn 25, which
sits on insulators, has a 2-inch mast extending the height to 75 feet. A spar at the top sticks out about 3 feet and
supports the top of the 160-meter T element. The ends of the T are supported by trees.
Element 3 is temporarily an inverted L with 55 feet vertical and 74 feet horizontal. The end of the horizontal
element is supported by the Element 2 tower.
Element 4 is another inverted L the same size as element 3, strung between a 100-ft tower and a tree. The
horizontal section runs away from the tower and element 1.
Broadside spacing is 327 feet between elements 1 and 2 and between 3 and 4.
Endfire spacing is 146 feet between elements 1 and 4 and between 2 and 3.
Element 1 has a complete 120-radial field and no. 2 is nearly complete. Element 3 has about half done and
Element 4 only has 6 for the moment.
Each element will be fed by a 3/4 electrical wavelength of 7/8" Prodelin running to a central switching
and phasing point. For now only the feeds from elements 1 and 2 are being used, connected at a T to the 7/8" Prodelin feedline
running to the shack. This produced a low SWR so no additional matching was necessary. The Alpha 89 is happy. Elements 3 and
4 are grounded through a coil that resonates each at 1895 kHz so they serve as reflectors. Later these elements will be phased
with the other two so the array is switchable NE and SW as well as some other options. For now it is fixed NE (Europe) and
initial tests show it has significant gain over the existing 4-element in-line parastic array, as expected.
The antenna was temporarily completed the night before the CQ WW 160m CW 2012 contest and is getting its
first workout in that.
The first night proved a bust for conditions with only 17 Europeans in the log. But the band broke loose
the second night with more than 260 ten-pointers in the log and this antenna proved an improvement over the old parasitic
array.
