Hi Pete.
Modeling your antenna with the horizontal wire 30' above GND an EZNEC sweep
across the band shows R varying from 27 to 34 ohms with X varying from -j55
to +j55 ohms.
Modeling your antenna with the horizontal wire 50' above GND an EZNEC sweep
across the band shows R varying from 27 to 34 ohms with X varying from -j48
to +j49 ohms.
Modeling your antenna with the horizontal wire 70' above GND an EZNEC sweep
across the band shows R varying from 27 to 34 ohms with X varying from -j44
to +j44 ohms.
EZNEC, NEC-2
0.005/13 GND
Radials 1' above GND
Loss resistance added to achieve 30 ohms resistive at 1900kHz
Horizontal length adjusted for resonance at 1900kHz
Dave KH6AQ (formerly WX7G)
On Sat, Mar 13, 2021 at 6:05 AM N4ZR <n4zr@comcast.net> wrote:
> I have just finished replacing my 1/4 wave 160-M inverted L, which broke
> this winter at the bend. It has 8 ca. 70-foot on the ground radials. I
> measured the R and X at the feedpoint with a RigExport AA-55 Zoom, and
> the R was 30 ohms more or less across the entire band, while X slowly
> converged to resonance above 1900 KHz. My questions are these - is a
> relatively flat curve to be expected, or a sign of something wrong? And
> is 30 ohms reasonable for an antenna with such a sparse radial field?
> All I have at the bottom is a common mode choke, wound of 17 turns of
> RG-400 on (I think) a type 43 core
>
> --
> 73, Pete N4ZR
> Check out the new Reverse Beacon Network
> web server at <http://beta.reversebeacon.net>.
> For spots, please use your favorite
> "retail" DX cluster.
>
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