Topband: Inverted L capacity hat
herbs at vitelcom.net
Sat Sep 5 06:19:38 PDT 2009
> 2.If I use 4 top wire ,antenna will radiate 4 direction?
Normally with four wire top hats of equal length have a cancellation
effect on unwanted horizontal radiation while adding need length to a
short Marconi. However they should not be much more than 20-30 feet or
slope down at more than 45 degrees inregard to the horizontal plane..
Assuming you have sufficient radials in or lying on the ground, a 65
foot vertical with 4 25 foot top hat spokes should perform well on 160
meters. Your feed point impedance, although I have not modeled this
configuration, should be in the vicinity of 20 to 30 ohms so proper
matching is required. If you have an antenna bridge and you find a
radiation resistance that is, let say 65 to 75 ohms, this may indicate
that you need to put down more radials to bring the impedance closer to
the actual value of the antenna modeled over a near perfect ground thus
reducing power robbing loss resistance.
Herb Schoenbohm, KV4FZ
> Normal inverted L radiates only one direction? Lot of difference or not?
> 3.I have limited space for radial,no space for 1/4 wave radial ,I have only 15m(45 foot) for each direction?
> Anybody tried to use trap radial? To use a coil or capacitor in each radial? Or not?
> Thanks :Laszlo
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