I plan to do EZNEC hoping to gain some intuition. I agree about the nulls.
Probably a clover pattern of some sort. In retrospect, probably a fan
dipole or folded dipole would have been better. Not sure how far apart
conductors need to be in a fan dipole. But mounting widely spaced parallel
conductors is more difficult than attaching a 20 oz soda bottle filled with
water (but leaving some room for expansion of ice) to a simple wire and
throwing into trees.
Best,
Barry WA2VIU
--
Barry Jacobson
WA2VIU
bdj@alum.mit.edu
@bdj_phd
On Mon, Feb 6, 2023, 10:14 PM <john@kk9a.com> wrote:
> You mentioned in your post going on EZNEC. You definitely should model your
> 80m dipole for all of bands that you use it on. I think you'll find that on
> 10m it has a high impedance and a number of very deep nulls in the
> radiation
> pattern.
>
> John KK9A
>
>
> Barry Jacobson WA2VIU
>
> Hi, I need advice on getting one of the antenna analyzers on the market. I
> have an 80 meter dipole fed with ladder line from an MFJ 989D tuner. I
> seldom use 10 meters, but tried to go on the 10-10 phone contest today.
> Would not tune in that segment of band. Tuner instructions say most
> commonly need to shorten feedline by 1/8 wavelength at band that won't
> tune. Before cutting line and possibly messing up other bands that work
> fine, I would like to know exactly where I stand on each band. I could use
> a device that will tell me exact length of line currently, and what effect
> shortening will have on all other bands, and whether the new impedances
> will be within range of capability of tuner. I don't mind learning complex
> impedances and Smith charts if necessary, but want to do it systematically.
> Don't know if devices out there do this for you. Some possibilities I have
> heard of are NanoVNA, Rigexpert, MFJ antenna analyzer. I don't know if I
> should go on EZNEC. The last 15 feet of each end of dipole droop
> vertically, but don't think that's the main problem.
>
> There is a whole page of devices. Don't know where to begin.
>
> https://www.eham.net/reviews/view-category?id=31
>
> Any advice from an expert greatly appreciated.
>
> 73,
>
> Barry
>
> --
> Barry Jacobson
> WA2VIU
>
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