Topband: Shunt fed T

john jb at beaumonts.karoo.co.uk
Sun Jan 3 22:43:58 PST 2010


I posted over christmas a question of gamma matching, thanks to everyone for the replies.
Could anyone advise me about top loading when 4 wires are use as an alternative to 2 with this type of antenna. My present antenna is 82ft vertical with 4 top lading wires each 35ft long,  I have been told only 1 wires counts as the loading/lengthening on this type of antenna which I dont fully agree/understand. Is it not that a 2 wire tee you calculate the missing portion of your vertical lets say I needed 127 ft for 1.83mhz and my vert is 82ft so 45ft too short, so lets say 60% of 45ft = 27ft I would need 2 top wires 27ft or maybe 70% of 45ft = 2 x  31.5 ft.

Am I on the right lines, what if I use 4 wires the reason been its better for guying and I thought the 4 shorter ones mean less cancellation of the vertical radiator!! Obviously I can use 2 rope for the missing guys but I thought 4 wires may be better

I have not seen any info on using more than 2 wires at least not unless we look at a horizontal capacity hat constucted with rods and wires.

regards HNY all
John Beaumont G4EIM


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