I've seen a setup of 3 phased verticals (in a 60degree triangle space)
where - with the help of switches, relays, and various lengths of coax, the
operator could choose any of 6 directions with a switch, then the relays
would cut in appropriate phasing lengths . The wiring of the relays would
keep me busy for quite a while.
Heck - grandma used to keep us occupied by putting molasses on our hand and
giving us a feather

Roy Lewallen wrote:

There's no single perfect antenna -- you pays your money and you makes
your choice. As Richard Heinlein so succinctly said, TANSTAAFL.

Roy Lewallen, W7EL


Robert Anson Heinlein. A master in his field, as you are in yours.

tom
K0TAR

My apology, to the readers and to the late *Robert* Heinlein.

Roy Lewallen, W7EL

Tom Ring wrote:
Roy Lewallen wrote:

There's no single perfect antenna -- you pays your money and you makes
your choice. As Richard Heinlein so succinctly said, TANSTAAFL.

Roy Lewallen, W7EL


Robert Anson Heinlein. A master in his field, as you are in yours.

tom
K0TAR

On Tue, 19 Apr 2005 19:17:34 -0700, Roy Lewallen
wrote:

My apology, to the readers and to the late *Robert* Heinlein.

No problem; I'm sure he won't mind.

What would happen if you isolated that second driven element from the boom
(the one you are effecting the phase-shift in, and added another reflector
( naturally it is in proper phase) behind it? Could you get the best of two
worlds? The advantage of the phase-shift plus a FB ratio?

Regards,
John

"Roy Lewallen" wrote in message
...
There are a couple of distinct advantages of the W8JK over the antennas I
described. One is that it can be fed with two equal lengths of
transmission line to the elements, one being given a physical half twist
to effect the phase reversal. Then you have an antenna whose properties
remain the same over an extremely wide bandwidth. The second is that the
free-space pattern consists of two relatively narrow lobes in the vertical
plane, with an overhead null. This results in a concentration of radiation
at lower angles than you'll get with a typical Yagi or most other two
element horizontal antennas.

The tradeoffs are that because of the bidirectional pattern, half the
radiation doesn't do you any good; there's no front-back ratio (although
it's also poor on the maximum-gain antennas I described); and loss has to
be managed and can potentially be a problem because of the low feedpoint
impedances.

There's no single perfect antenna -- you pays your money and you makes
your choice. As Richard Heinlein so succinctly said, TANSTAAFL.

Roy Lewallen, W7EL

Richard Harrison wrote:
Roy, W7EL wrote:
"The W8JK doesn`t provide thye most gain of any two element array of
half wavelength elements for a given spacing."

The W8JK had the highest gain of the 5 examples compared in the table.

The advantage of EZNEC is shown in Roy`s posting.

Roy also wrote:
"At 0.25 wavelength spacing, 142 degree phasing gives the highest gain,
just over 1 dB greater than a W8JK. These phasings also provide a higher
nfeedpoint impedance than a W8JK,---."

I`d rather have Roy`s antenna.

Best regards, Richard Harrison, KB5WZI

Hal Rosser wrote:
I've seen a setup of 3 phased verticals (in a 60degree triangle space)
where - with the help of switches, relays, and various lengths of coax, the
operator could choose any of 6 directions with a switch, then the relays
would cut in appropriate phasing lengths .

G3HCT (now VK4OQ) used this system for 40m. By phasing any pair you have
a choice of six 2-element beams, with the third element inactive
(open-circuit).

The gain is about 1.5dB lower than a four-square, comparing both beams
in their best (forward) direction, but the triangle has more directions
to choose from, so in some directions it's actually ahead of the 4sq.

The verticals were quite closely-spaced, and phased to give *two*
rearward nulls at around +/-120deg. That gave a total of 12 switchable
nulls on receive, which can be very important in European QRM.

The wiring of the relays would
keep me busy for quite a while.

Four DPDT relays take care of everything.

Heck - grandma used to keep us occupied by putting molasses on our hand and
giving us a feather

'Eck - i' Yorkshire we only had... [insert rest of Python sketch here].


--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek

John Smith wrote:
What would happen if you isolated that second driven element from the boom
(the one you are effecting the phase-shift in, and added another reflector
( naturally it is in proper phase) behind it? Could you get the best of two
worlds? The advantage of the phase-shift plus a FB ratio?

That's just the sort of thing antenna modeling programs are for. And
they're good at it.

Roy Lewallen, W7EL

LOL!!! Hmm, I wonder if anyone sells one? grin

Warmest regards,
John

"Roy Lewallen" wrote in message
...
John Smith wrote:
What would happen if you isolated that second driven element from the
boom (the one you are effecting the phase-shift in, and added another
reflector ( naturally it is in proper phase) behind it? Could you get
the best of two worlds? The advantage of the phase-shift plus a FB
ratio?

That's just the sort of thing antenna modeling programs are for. And
they're good at it.

Roy Lewallen, W7EL

John Smith wrote:
What would happen if you isolated that second driven element from the boom
(the one you are effecting the phase-shift in, and added another reflector
( naturally it is in proper phase) behind it? Could you get the best of two
worlds? The advantage of the phase-shift plus a FB ratio?

You can get all the FB you want using two driven elements
and Roy's simpfeed software.
--
73, Cecil, W5DXP

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I am going out today and see if I can't fit this all on a boom six foot long
or less, drop that 1/4 wave phase reversal line, replace it with a 1:1 phase
reversal balun and see just how close I can jam two phase reversed driven
elements together... I need a tan anyway... grin

Regards,
John

"Cecil Moore" wrote in message
...
John Smith wrote:
What would happen if you isolated that second driven element from the
boom (the one you are effecting the phase-shift in, and added another
reflector ( naturally it is in proper phase) behind it? Could you get
the best of two worlds? The advantage of the phase-shift plus a FB
ratio?

You can get all the FB you want using two driven elements
and Roy's simpfeed software.
--
73, Cecil, W5DXP

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