[Elecraft] AX1 dipole

[David Gilbert]

You're talking about a horizontal pair of AX1's ... I asked about them 
oriented vertically.  That wouldn't require them to be as high above 
ground as you mention and would still allow them to be carried 
pedestrian mobile.

I modeled a vertical pair at the same height above ground (15 feet) as I 
did before with a 13 foot hanging counterpoise wire simply to make a 
semi-valid comparison.  According to EZNEC, two 4' loaded whips oriented 
back to back were down anywhere from 4 to 9 dB from a single loaded whip 
with the hanging 13 foot counterpoise, but not surprisingly that was 
heavily dependent upon what assumption I made for Q of the coil.

Since most pedestrian mobile operations would involve at least half of 
the 13 foot counterpoise wire being dragged along the ground and 
therefore less effective than if all of it was oriented vertically like 
I modeled it, I suspect that a single AX1 with the counterpoise and two 
AX1's oriented as a vertical dipole would be similar in performance.  
The single AX1 would of course be simpler, less expensive, and easier to 
carry while operating.

As an aside, it seems to me that AX1 or similarly loaded short whip with 
a trailing counterpoise wire is probably the most efficient setup for 
pedestrian mobile.  For fixed portable operation (camping, SOTA, etc), I 
would probably go for whatever larger configuration I could easily carry 
and setup quickly ... such as that full sized portable vertical antenna 
I mentioned in an earlier post.  I think it would have a significant 
field strength advantage.  I might even build two of those portable 
verticals just to find out how much advantage compared to a short loaded 
whip with a counterpoise.

73,
Dave   AB7E



On 9/29/2022 4:14 AM, Wayne Burdick wrote:
> We studied this. To provide any advantage over a vertical AX1 with a single counterpoise wire, an AX1 dipole would have to be well over a quarter wavelength above ground, with both halves tuned to resonance, and fed with low-loss coax and a balun or balanced feedline. Even then the advantage is small and only in the dipole's broadside directions.
>
> That said, a pedestrian-mobile version of the dipole held a few feet above the operator's head would eliminate the dragged counterpoise. I'd be concerned about nearby trees and ogling passersby.
>
> 73,
> Wayne
> N6KR
>
>
>
>
>> On Sep 29, 2022, at 4:05 AM, Rich WC3T <rich at wc3t.us> wrote:
>>
>> Interesting idea.
>>
>> 72,
>> Rich Hurd / WC3T / DMR: 3142737
>> Grid: FN20is
>> Bureaucracy is always in search of self-preservation.  — AA7BQ
>>
>>> On Sep 29, 2022, at 04:14, David Gilbert <ab7echo at gmail.com> wrote:
>>>
>>> 
>>> Has anyone ever tried to used two AX1's back to back as a vertical (not horizontal) dipole?  And if so, how did its performance compare to a single AX1 with the 13 foot counterpoise wire?
>>>
>>> Just curious.
>>>
>>> 73,
>>> Dave   AB7E
>>>
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