SWR PLOTS (Taken with Palstar ZM-30 analyzer)



On topband the transmit antenna is an inverted-L with (32) 1/4 wavelength ground radials. This is a seasonal antenna as the radials are rolled out on the back lawn in late October after the leaves get raked up each year and then rolled back in when the snow melts in April.

At left is the 160m inverted-L feedbox with the front cover removed showing the 1000 pf vacuum variable capacitor installed in series. The overall length of the antenna is slightly longer then a 1/4 wavelength and the capacitor can be adjusted to resonate the antenna anywhere in the band. This configuration yields a 2:1 SWR bandwidth of almost 60 KHz.

In 2009 I installed a K9AY loop to improve low band reception. Like anything else on topband this was a compromise due to real estate constraints and the close proxmity to other low band antennas.