On 160 and to a lesser extent 80 RX antennas prove out better than TX
antennas for listening. Set your TX antenna for some compromise of gain,
bandwidth and azimuth coverage. As most RX solutions work on two or three
bands well, getting 160 and 80 RX in a single solution is really not that
hard.
N4AF/NY4A had an 80 meter 4 element wide-spaced wire yagi from inverted vee
elements off a 220 foot catenary and supporting towers, lovingly named "Big
Mother." THAT antenna heard as well as it transmitted. But it used an awful
lot of real estate.
Best to do RX and TX separately for 160 and 80. Lacking a Big Momma, a K9AY
will generally hear better than any TX wire on 160/80. Anything better than
a basic K9AY is additional gravy.
73, Guy K2AV
On Sat, Apr 1, 2017 at 2:21 PM, jimlux <jimlux@earthlink.net> wrote:
> On 4/1/17 10:37 AM, Richard (Rick) Karlquist wrote:
>>
>> Not mentioned in the discussion:
>>
>> For 2 elements, a driven array can be tuned up for really high
>> F/B ratio, like 20 to 30 dB, maybe even 40 dB on a good day.
>> A 2 element Yagi will never do more than 10 dB or so F/B.
>
>
>
>
>
>
>>
>> On receive, a 2 element driven will have a pattern very close
>> to a 3 element Yagi. Often, receiving on 80 is the limiting
>> factor.
>>
>
>
> I wonder how often you need that null "in the back" as opposed to
somewhere
> else? With a 2 element array, you can form a single null, but most
> directions, you get two main lobes and two nulls (mirrored around the line
> connecting the two elements. That might be ok, though.
>
> On the other hand, I can think of cases where what you want is a generally
> low response to some wide range of azimuths (say you're on the outskirts
of
> a noisy city). It's "lower average sidelobe level from 100 to 260
degrees"
> ...
>
> On receive, I would think that *gain* isn't as big a deal since background
> noise is higher - that is, if your goal is to place nulls, smaller
antennas
> work just fine for the "null forming" signals.
>
> So some sort of switched array for Tx (picking phases and spacings that
are
> "easy") to squirt your power in the generally desired direction, and then
a
> separate receive array (perhaps sharing elements from the Tx) to optimize
> the receive.
>
> On Tx, it seems that horizontal pol is what you want (unless you live in
the
> proverbial salt marsh) for best low angle radiation. But what about on
Rx?
>
>
>
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