>Johan Van de Velde,ON4ANT wrote:
>> while in mounting position, the bottom of the diamond shape is only 2 ft
>> above ground
>> the resonance is around 7200 khz with a 1.5 swr bandwith of 150 KHz..
>> The quad goes up to 80ft (central point)..
>> Will the resonance go up or down ????
Hi, IMO, the resonance will almost certainly go higher.
Near the ground, you have coupled in much reactance from the
ground, which pulls the resonance lower. When you go up the
tower, you will loose much of the coupled reactance, so up will
go the resonance of the antenna. Put another way, were it a dipole,
near the ground the length would yield one resonant frequency, and
when up in the air, you would have to add wire on the
dipole to get back down to the resonance you had while near the
ground.(I guess actually, you would lower the antenna, add some
wire length, crank it back up and see what happened -- usually
take a couple tries or so, to get the frequency you want, or you
decide it is close enough already!)
Not sure how you do this with a quad, as where the wires string on
the spreader depends upon the wire length; longer wires must go
further out from the hub. Anyway, thats my 2 cents.
73, Jim, KH7M
FAQ on WWW: http://www.contesting.com/towertalkfaq.html
Administrative requests: towertalk-REQUEST@contesting.com