I've had some nice correspondence with Al K3LC on various antenna topics and
he has kindly done some calculations for me. One topic was bandwidth with or
without toploading. The exercise involved my 90 foot irrigation pipe vertical
(see ON4UN handbook) with 4 top loading wires. Al found that the performance
was almost the same with or without the toploading, but with those wires the
bandwidth was very much better (wider).
Here are the numbers, measured on the TS-850 in my shack. Network 1 and 2
are L networks each with two ceramic doorknob capacitors. The array is of two
90 foot verticals, 90 foot spacing, with coax cable (see ON4UN handbook again)
and an L network matching; about 4.5 db gain endfire to Europe or New Zealand.
Network 1. swr 1.6 to 1.0 between 1800 and 1910 KHz, swr 2.0 at 1980 KHz
Network 2 swr 1.0 to 2.1 between 1920 and 1999 KHz, swr 2.0 at 1860 KHz
Array swr 1.0 to 2.0 between 1800 and 2000 KHz
These might sound like a dummy load, but in late October I worked about
50 European stations plus 4X4WN, sending my call twice with 1.5 kw, and often
hearing them calling me after the zoo had died down.
73 Bob W7LR in MT lots of snow and cold Happy New Year
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