|To:||Jim Lux <firstname.lastname@example.org>,"R. Kevin Stover" <email@example.com>,TowerTalk <firstname.lastname@example.org>|
|Subject:||Re: [TowerTalk] Antenna modeling|
|From:||Pete Smith <email@example.com>|
|Date:||Wed, 08 Dec 2004 13:18:32 -0500|
At 12:07 PM 12/8/2004, Jim Lux wrote:
#3. When modeling an antenna with traps how do you know what values to plug in as loads for the traps?
This what I have done with linear loading, as well. Simulating it with a lumped inductance and the right length elements gives me what I choose to believe is a sufficiently high-fidelity model for interaction and similar large-scale phenomena. Some modern antennas -- the F-12 C'3s come to mind -- probably won't give you believable feedpoint impedances anyway -- but the patterns seem to be pretty credible.
Some very effective tri-bander stacks have been designed using single-band monotaper models of antennas like TH-7s, bypassing the whole tra\sp exercise altogether
Modeling antennas with LC traps could be a real pain in cut and try mode, given all the possible combinations that will resonate at a particular frequency. In that connection, AC6LA's MultiNEC is a really neat tool, because it will let you automatically alter multiple parameters in a design singly or all at once, producing hundreds of runs from which you can select.
73, Pete N4ZR
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions and ask for Sherman, W2FLA.
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