Horseshoe antenna works, bi-directional beam. stay tuned. 225nm

galenthurber

galenthurber

New Member
Just built an ugly horseshoe antenna; it works.
it's a smaller version of a 145Mhz one.
each arm (L shape) has 1/4wave horizontal & 1/2wave vertical.
The antenna is fed where the open end of the horizontal element arms almost touch; 10mm apart.
The feed line must come in at 90degrees to the horizontal elements.
The antenna is mounted 4' lower than my main ADSB antenna and it has reached 132nm so far.
the pattern should egg shaped off of each end.
Aim the antenna like gunsights.
stay tuned
 
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antenna flightradar24-horseshoe_2018-10-20_08-11-51.png
antenna flightradar24-horseshoe_2018-10-20_08-11-51.png
 
early results are quite promising. Instead of the meat of collected data was spotty & below 50nm now it is 50-100nm, tracking now has solid tracking out to 125nm.
Spikes up to (polar plot pfclient reporting) 225nm
 
ALSO I switched SDRs. Now using Nooelec SmarTee, instead of Nooelec SmarT which has birdies / internal noise spikes at 1080, 1087.2, 1094.4Mhz etc (nasty) My SDR gain for feeders is at manual, max.
So ...
 
yes that's the type, mine is inverted.
My equipment is limited to testing the SWR at frequencies below 529Mhz.
mhz swr
515,4.7
512,5.1
510, 7.1
but I'll need more data points inorder to fill in for the missing arm of the complex parabola.
The good thing is that the best SWR is above 515Mhz, so I didn't totally screw up.
 
Had a go at this, made to 69mm,69mm and 138mm (1/4,1/4,1/2 wave)
not very impressed.
 

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