Loop on top of a discone

bearcatrp

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Just a wild thought so decided to ask. Since finding out my discone does fairly well on HF bands, started wondering if there was a way to make it a little better. When I tested my 60 foot wire to my discone, was actually shocked how well it performed. So, started thinking, can a taller whip twice the size help. Then thought about how allot of folks praise a loop. So, how about a 12 to 16 inch loop replacing the whip on top of a discone. Just hinking outside the box on this but thought I would ask.
 

merlin

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Jul 3, 2003
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HF discones are BIG. The typical VHF/UHF perform awful down to HF frequencies if at all.
Anything above the 'top hat' just degrades performance. I see those with verticals on top, but the overall antenna is no longer a flat performance. You then have gain nodes and loss nodes.
HF loops work better in an open area and just above the ground. about 2X the diameter seems best.
Here is sort of double discone design for 20 meters, it is goof into VHF bands:
 

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prcguy

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I don't think you could make use of an HF loop without some very unconventional way of feeding it. A small loop, untuned, has an impedance close to 200 ohms over much of the VLF through HF bands. You would need to have a matching transformer or preamp for the loop, then how do you connect that to the common coax below the top disc?

There might be a way to run a few inches of parallel line down through the top disc from the loop to a diplexer that combines the VLF/HF bands of the loop and VHF/UHF bands of the Discone, but at that point why? You could just mount a small loop nearby and get predictable performance from that separate from the Discone.
 

bearcatrp

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Well, it was just a thought. Looks to be a moot point trying. Didn't want a second antenna. Will have to think about sticking with the discone or replacing with a loop. Thanks folks.
 
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