Phasing

I have been studying about phasing antennas in my Amateur Extra book and was wondering, is it possible to phase a 2 meter vertical and a 2 meter vertically polarized beam? Just curious.

[ve6wtf]

Dunno all i have is a 11 element phased 2 mtr beam

[K8MHZ]

If you mean feeding the antennas in or out of phase, sure. It is easily done with varying lengths of coax.

My question is why would you want to do it? The beam already has more gain than the result of a combination of itself and a lesser antenna no matter how it is fed.

[ve6wtf]

Well you increase directivity?
and from What I have been told gain as well.

[W0LPQ]

How perchance do you increase gain? A vertical has 0 gain. The beam has some gain. Whatever the spec's call for.

Adding any kind of phasing line, will cut down the available power to each antenna.

Why would anyone want to do this is beyond me.

If you want to switch between them ... install a remote relay.

Bill, W0LPQ/9

[ve6wtf]

one: you null one station out to hear another station on the same frequency.

And well if you look at it, Every single yagi made,
Puts the technique of phasing in effect!
Just the lengths of the elements and their spacing can change the current magnitude and the phase on the reflector relative to the driven element. There are good combinations and bad combinations. and there is a limit to both gain and front to back ratio.

Antenna's can be vertically and horizontally phased.
For more gain. the principle is to place the two patterns in a proper phase relationship so that the forward patterns add a vertical or horizontal version of thecollinear pattern.

[ve6wtf]

I win!!

[dj1yfk]

Into one particular direction, you'll never gain anything from this configuration.

Moreover, you can hardly avoid that you even create some nulls in the overall pattern.

I don't see too much use for such a configuration, but trying it is cheap: All you need is a T-connector and a 1/4 WL transmission line with abt 36 Ohms (for example 2 * 75 Ohm TV in parallel), that's it.

[ve6wtf]

Works for me!
HIHIHI

[VK2AKG]

For transmission you would be well advised to reconsider Bill, W0LPQ/9 's posting as the phasing of two antennas with _similar_ directional patterns and gains is an entirely different matter to phasing a low gain omnidirectional antenna and a high gain beam. For reception in the presence of a nearby source of strong QRM such a combination might be worth considering. Normal disclaimers apply. ' 73 Frank

[K6UEY]

To correctly phase elements of an array the elements should all be the same input Z .That includes the radiation resistance plus all the intercoupling between elements of the array. The use of coaxial cable as phasing elements is not a good idea. As you change the length of the cable to achieve the proper phase the Z of the signal changes also . So you wind up with a different Zo on part of the array. That changes the amount of power supplied to that portion, which changes the pattern,defeating the purpose in the first place.
The correct way would be to feed all elements with the same Zo of the same length of cable. One element would have the phasing section with Zo in and Zo out.The transmission line would then match the input of each element and supply the same amount of power,with one having the proper change in phase.
Stacking elements of an array will lead to narrowing the beam width and increasing the Gain.Doubling the number of elements will cut the beam width in half and increase the gain by 3 dB. Of course we all know it is not dynamic gain, but static gain, you are borrowing from peter to pay paul. You can modify the pattern by stacking in the "E" plane or stacking in the "H" plane. Side by side or one above the other .

[VK2XGC]

Gday

You most certainly can phase a vertical and beam together.

You end up with an antenna referred to as a "keyhole antenna" due to the shape of the radiation pattern from it.
You need to be sure both antennae are tuned to the same frequency (obviously) and you use the conventional phasing harness arrangements you see in ARRL books or you can construct a simple splitter combiner to do the phasing job.
Its a good antenna to seek and respond with.

Regards
Gary VK2XGC

[kl7aj]

Quote[/b] (kc0vvu @ Dec. 12 2006,16:24)]I have been studying about phasing antennas in my Amateur Extra book and was wondering, is it possible to phase a 2 meter vertical and a 2 meter vertically polarized beam? Just curious.
You certainly can, but it might be mighty hard to figure out the exact pattern. This might be more effective if you're trying to NULL out a station.

eric

[VK2XGC]

More info re the phased vertical and beam on 2m.

For those of you who cant see the benefit or why anyone would want to use this configuration there is a nice little write up in ARRL Antenna Book 18th edition pages 17-1 to 17-3 about the keyhole antenna.

[KC9KXW]

Good morning guys, well I'm a deffinate newbie here, waiting on my call letters (passed my Tech exam yesterday morning).

I'm confused as to why you would want to use the vertical and beam together in the first place. Your vertical would give you good local coverage as well as give you an idea of which direction the DX is coming from.

After you know which direction the DX is coming from, you would use your beam to focus your received and transmitted signal where you want. Also by rotating your beam you could use it to find distant stations if you were hunting for a specific area.

Am I right or not, like I said I'm a newbie, so I won't try to step on toes here. I'm just a little confused as to how you would gain with this setup, and wouldn't you actually be inviting QRM and QRN in anyways ?

Sorry for being long winded. 73 Jim http://www.qrz.com/iB_html/non-cgi/emoticons/wow.gif