Topband: EZnec - 4nec2 - MODELING THE 1/4 SLOPERS.

[Herb Schoenbohm]

Jim.....You hit on a good point with a 1/4 sloper that it should be some 
distance, in your case 5 feet, from the tower at the top or high voltage 
end.  Having the top right at the tower seems to deteriorate the 
performance overall as many who have tried this seem to underscore.  
What you have presumably are two verticals with an a periodic reflector 
which is your tower.  Having switchable gain both on RX and TX and some 
F/B is great. I am glad you confirmed this with both NEC and on the air 
tests.

Regards,

Herb Schoenbohm, KV4FZ




On 3/8/2014 2:38 PM, Jim Brown wrote:
> On 3/8/2014 9:08 AM, Herb Schoenbohm wrote:
>> IMHO a wire 1/4 wave length long wire should preferably be 
>> electrically connected to the tower and fed from the bottom of the 
>> slope against a good ground system. 
>
> Herb,
>
> That depends on the height of the tower. I have two sloping wires on 
> opposite sides of my 110 ft tower (with SteppIR and 2M long Yagi on 
> top) that are INSULATED from the tower and each fed from the bottom 
> against four radials elevated about 20 ft. The tower is grounded and 
> has a dozen or so quarter wave radials. The wires are held 5 ft away 
> from the tower at the top by a 10 ft section of 4-in PVC conduit. One 
> faces to 70 degrees, the other to 270 degrees. NEC predicts the same 
> gain of 2-3 dB with F/B of about 6 dB, and that's about the way they 
> hear. I feed one or the other, with a stub in the shack that opens the 
> feed of the antenna not being driven.
>
> 73, Jim K9YC
> _________________
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