Flipping turnstile
 

A turnstile is a horizontally polarized antenna. Big downer is that from a
polar radiation POV, from the sides, it's got a minus figure. Like -2db or
something.

Okay, flipp the turnstile so you have one dipole vertical. Not a turnstle
anymore, and the element configuration will respond favourably to both
vertical and horizontal radiation.

But:

1) Do you have to wire up the "flipped turnstle" in a different way in
order, at the same time, (without any switching) to take advantage of:

a) mixed polarized waves?
b) vertical or horizontal waves?

2) If you put up a "flipped turstile" and you wire it up to handle mixed,
vertical or horizontal waves, what is the polar radiation patter in the
horizontal plane (ie from the sides) ? Still a minus?

Amhoping that a "flipped turnstile" properly wired would perform with
mixed, vertical or horizontal waves coming from the sides. And hoping better
than a turnstile.

TIA.

"Richard" wrote in message
...
A turnstile is a horizontally polarized antenna. Big downer is that from
a
polar radiation POV, from the sides, it's got a minus figure. Like -2db
or
something.

I'd call it 'circular' polarization... but OK...

Okay, flipp the turnstile so you have one dipole vertical. Not a
turnstle
anymore, and the element configuration will respond favourably to both
vertical and horizontal radiation.

What happened to the ground plane
when you did that? Is one element
touching it now? The antenna will
have a bi-directional pattern unless
you include the plane to work against
(not necessarily bad...).

But:

1) Do you have to wire up the "flipped turnstle" in a different way in
order, at the same time, (without any switching) to take advantage of:

a) mixed polarized waves?
b) vertical or horizontal waves?

The only time circular is a disadvantage is
when the incoming wave is circular, and
opposite to what you're receiving.


2) If you put up a "flipped turstile" and you wire it up to handle
mixed,
vertical or horizontal waves, what is the polar radiation patter in the
horizontal plane (ie from the sides) ? Still a minus?

It'd be a null... about like a dipole
of that polarity (I'm guessing...).


Amhoping that a "flipped turnstile" properly wired would perform with
mixed, vertical or horizontal waves coming from the sides. And hoping
better
than a turnstile.

An interesting array might be a XYZ affair,
three crossed dipoles. Switchable to
choose the best axis to null.
__
Steve
KI5YG
..

Richard wrote:
Am hoping that a "flipped turnstile" properly wired would perform with
mixed, vertical or horizontal waves coming from the sides. And hoping
better than a turnstile.

TIA.

When I think about a flipped turnstile (though not necessarly wired up as
per a regular horizontal turnstile: Maybe, me thinks there is a better way
to wire up, given I'm seeking an antenna that is optimal for reception of V,
H Mixed waves) I think:

Vertical dipole part is going to act as a vertical dipole so flipped
turnstile is omnidirectional for V waves. So, you are going to get the same
signal from the flipped turnstile as you would a regular V dipole?

Horizontal dipole is going to act like a horizontal dipole so there will be
figure of eight pattern for H waves. So, you are going to get the same
signal from the flipped turnstile as you would a regular H dipole?

Downside is the figure of eight pattern with H polarization. Need a
turnstile with vertical dipole elements to avoid this.

What happens when the TX is radiating a mixed polarized signal. If wired
correctly, V dipole adds it's signal voltage to H dipole?

But you might as well have two seperate dipoles- right!! :c)

Selling point of regular turnstile is the omidirectional pattern. You loose
that with a "flipped turnstle"

Might as well have a turnstile and a vertical dipole if you wanted
omnidirectional reception capability catering for V or H polarized waves.

Conclusion: No point in flipping over a turnstile! So it seems. Much better
to erect V and H polarized dipoles, or V dipole and turnstile.

Paste below

Not totally sure of your physical concept, but the free space net patterns
of single, quadrature-fed h-pol and v-pol, 1/2 wave dipoles having
coincident radiation centers will be essentially c-pol on the planes normal
to the two dipoles, and essentially v-pol off the ends of the horizontal
dipole.

This is a common element configuration to generate c-pol in FM/TV broadcast
panel antenna arrays.

Two h-pol dipoles in a turnstile arrangement would be more omnidirectional,
in the azimuth plane.

RF

Visit http://rfry.org for FM broadcast RF system papers.

____________________

"Richard" wrote in message
...
A turnstile is a horizontally polarized antenna. Big downer is that from
a
polar radiation POV, from the sides, it's got a minus figure. Like -2db
or
something.

Okay, flipp the turnstile so you have one dipole vertical. Not a
turnstle
anymore, and the element configuration will respond favourably to both
vertical and horizontal radiation.
But:

1) Do you have to wire up the "flipped turnstle" in a different way in
order, at the same time, (without any switching) to take advantage of:

a) mixed polarized waves?
b) vertical or horizontal waves?

2) If you put up a "flipped turstile" and you wire it up to handle
mixed,
vertical or horizontal waves, what is the polar radiation patter in the
horizontal plane (ie from the sides) ? Still a minus? clip