Below are presented the results of actual measurements as well as EZNec modeling of both a 90 ft long End/Base-Fed Inverted-L 45 ft high and 45 ft across, as well as a 45 ft long Inverted-L 23 ft high and 22 ft across. Measurements of both were taken with a combination of a RigExpert AA-1400 and an HP8510 Vector Network Analyzer.
The 90 ft antenna is suspended by a pair of tall LobLollies, and is driven against a counterpoise system consisting of 14 surface ground radials and a low chain link fence.
The 45 ft antenna is supported by guyed mil tent poles and suspended to another LobLolly. This unit is driven against 16 surface ground radials.
For modeling purposes, a multi-connection distributed grounded counterpoise is used. This empirical structure provides a reasonable broadband counterpoise over the frequency range of interest.
MEASURED AND MODELED SWR
We see good agreement between modeled SWR and measured SWR for both the 90 ft antenna and the 45 ft antenna ===>
Dave Benzel – KD6RF – 2017 Jan 4
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