I talked to a guy in maine and he said he was running a y quad on both sides at the same time. Is there any advantage?
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vertical and horizontal transmission at same time
- Thread starter fisjr
- Start date
It will reduce fading due to polarity shift as well as allow you to receive either H or V polarity equally well at the same time. Many years ago I ran a Wilson Shooting Star and had it set up to run V or H or both at the same time. In theory there is a 3 dB loss on transmission when running both polarities at the same time due to the power being split between the two antennas. In practice this is overcome by the reduction of losses due to to the receiving station using the “wrong” polarity.The other disadvantage is that you have to pay attention to the lengths of cable feeding each antenna as well as the feedpoint impedance of each antenna.
The advantage is a compromise. It won't receive or transmit vertically or horizontally as strong as a vertical antenna or a horizontal beam will. But that can change if it is more than a simple V-quad. A multiple element V-quad will increase the gain to overcome that 3db phase loss mentioned by CK.
Dunno the difference between a V and a Y quad.
Is there? One would think they behave the same.
Dunno the difference between a V and a Y quad.
Is there? One would think they behave the same.
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Actually Robb, the Y quad or V quad will receive just as well when using BOTH polarities as it will on one or the other polarities at a time if the incoming signal is comprised of a single polarity as it generally is when working local stations. It is different on TX because you are feeding two antennas at the same time. The 3 dB loss I mentioned comes about because at no time can a transmitted signal ever be more than 45 degrees off on the receiving end and that equates to a 3 dB loss. As I stated, the biggest advantage is when the path between the two station causes the signal polarity to shift or rotate constantly which normally results in fading but using both polarities at the same time pretty much eliminates this fading problem. The most the signal will generally fade is 3 dB as opposed to more than 25 dB when using a single polarity.
I was giving my buddy a radio check on his pdl-2 he just put up...I checked him on vertical and then I checked him horizontal...then I checked him on V-H....his signal got weaker....that is all the input I have to offer.
I'd like to see it repeated with different stations under differing propagation. I'm just interested...
There is also a local who talks on a maco 3 element bean set at a 45 degree angle who gets out real good.
I was giving my buddy a radio check on his pdl-2 he just put up...I checked him on vertical and then I checked him horizontal...then I checked him on V-H....his signal got weaker....that is all the input I have to offer.
Who was using what polarity at the time? Signals should have been constant if you were both using the same polarity at the same time unless the path was a long local path,50 miles or more, and near sunrise or sunset. That can upset things a bit sometimes. If only one of you, most likely him, was using both polarities at the same time then that would account for the 3 dB loss I pointed out above. Also unless the length of coax cables was properly cut to allow for proper phasing then signals could cancel out with the amount of cancellation depending on the amount the two signals were out of phase. It's not a simple matter of screwing two cables into a TEE connector and it working right. The bottom line is that no single polarity or combination of polarities is going to be the best ALL the time but dual polarity at the same time is the best compromise and really pays off when the band is flakey and signals are fading up and down. that's the whole reason I configured my Shooting Star to be able to operate just V, just H, or both. I used both about 90% of the time.
Yeah...I was on my imax 2000.......most of the guys around here that use beams are gaw gaw over flat side......I would prolly have got a better signal if I was giving him a radio check with the same antenna set up V-H?
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Hard to beat a Quad antenna for fading on reception.
Orient the elements so you get both vertical and horizontal at the same time.
Sure you loose that 3db of tx power using both planes but it would reduce the fading.
For that matter a quad either vert or hor does not lose to much on the receive side for fade.
Only need one feed line.
Orient the elements so you get both vertical and horizontal at the same time.
Sure you loose that 3db of tx power using both planes but it would reduce the fading.
For that matter a quad either vert or hor does not lose to much on the receive side for fade.
Only need one feed line.
Captain, you raise an interesting point concerning the 3 db loss in TX with dual polarization. While in almost every case, gain is reciprocal in TX and RX, I see your point in this application where it just may be possible that this loss is not experienced in RX. Do you know of any references that would confirm this idea? I think you are correct since the matching polarized element should be able to capture just as much signal when combined with the second element in the wrong polarization.
If you run dual polarization and like the reduction in fade you see with DX signals, consider circular polarization instead. It seems we already acknowledge the fact the DX signal is always shifting its polarization and rarely in a perfect vertical or horizontal polarity. It's just as likely to be in between the two as it is in any one fixed polarization.
Simply delaying the phase by 90 degrees to either element with allow you to be in ALL polarizations simultaneously. All you need to do is add an electrical 1/4 wave of cable to one feedline (assuming both feed lines were the exact same length to start with). To correct the 25 ohm parallel impedance of both elements, a co phased 75 ohm matching harness should be used.
If you run dual polarization and like the reduction in fade you see with DX signals, consider circular polarization instead. It seems we already acknowledge the fact the DX signal is always shifting its polarization and rarely in a perfect vertical or horizontal polarity. It's just as likely to be in between the two as it is in any one fixed polarization.
Simply delaying the phase by 90 degrees to either element with allow you to be in ALL polarizations simultaneously. All you need to do is add an electrical 1/4 wave of cable to one feedline (assuming both feed lines were the exact same length to start with). To correct the 25 ohm parallel impedance of both elements, a co phased 75 ohm matching harness should be used.
if there is this much "discussion" about simple HORIZ/ VERT polarization, then a circular antenna will be a challange,.... circular antennas have a CW or a CCW polarization.
and
on TRANSMIT, feeding dual antennas 90 degrees out of phase will result in a LOSS in certain directions (a null) and an improvement (gain) in others.
also, it will not be "ALL polarization simultaneously", it will be horiz (90 degrees)AND vert (180 degrees) only
The only difference between dual polarization and circular is the addition of an electrical 1/4 wavelength of cable on one of the driven elements. It's actually very easy to achieve. The difference between left hand and right hand CP is which side of the antenna has the longer coax. Since most of the stations you will be working are not using CP, it won't make any difference if you use RHCP or LHCP. You will see the same signal stabilization in either case.
Feeding dual antennas 90 degrees only causes significant directional effects when both elements are in the same polarization. The effect is different when the two elements are physically orientated so they are turned 90 degrees from each other and electrically driven 90 degrees out of phase. Then you have a signal in all polarizations when transmitting and response to all polarizations in receive. Not 90 and 180 degrees. That's what you get when you combine the two with equal lengths and no phase delay.
I've also given more thought to the issue of whether you lose 3 db in receive with CP and have reverted back to my original thoughts on this. I base this on the need to combine the two elements to form either CP or dual polarity. When you combine the two coaxes through a pair of 1/4 wave 75 ohm cables, you have formed a two port, bi-directional splitter / combiner. This transforms the combined antennas impedance from 25 to 50 ohms but gives you a 3 db loss on either of the two ports in RX and TX.
If you just combine the ends of with a "T" connector, you still have a 3 db loss but it's from different reasons now. Two 50 ohm loads in parallel equal 25 ohms and will produce a VSWR of 2:1. Your VSWR meter may not show this much of an increase due to coax loss and the fact that the lengths of coax may not be reflecting the true VSWR at the antenna. That would require using coax lengths that are electrically equal to 1/2 wavelength multiples. Even then the reading will still be hiding some of the reflected power through coax loss.
Feeding dual antennas 90 degrees only causes significant directional effects when both elements are in the same polarization. The effect is different when the two elements are physically orientated so they are turned 90 degrees from each other and electrically driven 90 degrees out of phase. Then you have a signal in all polarizations when transmitting and response to all polarizations in receive. Not 90 and 180 degrees. That's what you get when you combine the two with equal lengths and no phase delay.
I've also given more thought to the issue of whether you lose 3 db in receive with CP and have reverted back to my original thoughts on this. I base this on the need to combine the two elements to form either CP or dual polarity. When you combine the two coaxes through a pair of 1/4 wave 75 ohm cables, you have formed a two port, bi-directional splitter / combiner. This transforms the combined antennas impedance from 25 to 50 ohms but gives you a 3 db loss on either of the two ports in RX and TX.
If you just combine the ends of with a "T" connector, you still have a 3 db loss but it's from different reasons now. Two 50 ohm loads in parallel equal 25 ohms and will produce a VSWR of 2:1. Your VSWR meter may not show this much of an increase due to coax loss and the fact that the lengths of coax may not be reflecting the true VSWR at the antenna. That would require using coax lengths that are electrically equal to 1/2 wavelength multiples. Even then the reading will still be hiding some of the reflected power through coax loss.
no,... it is NOT "ALL" polarizations when fed 90 out and Xpolarization.
this is basic turnstile antenna theory.
when 2 antennas are @ 90 degrees to each other and are fed 90 degrees out of phase and mounted horizontally the antenna is nearly omnidirectional on the horizontal plane.
When mounted vertically the antenna is directional to a right angle to its plane and is circularly polarized.
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