Yagi in between V/H

[314]

not sure if anyone has covered or had anytime to do this, but has anyone ever took lets say a Maco 103c ,104c etc....and placed it in between the H/V and did any tests..Just curious as if it would act as both or how the pattern would be.You always see it vertical, or you see it flat, but never in between....

 

[wavrider]

You mean sort of side ways?
Would seem to loose signal on both polarizations, horizontal or vertical.

It will work sure, but not as well as either true vertical or true horizontal.

Try it and find out see how it does.

 

[Road Squawker]

referenced to either a vertical or horiz antenna, the received signal value would describe a sine wave as the antenna is rotated about the axis.

the actual output power of the antenna would really be the same,

 

[Captain Kilowatt]

You would lose 3 dB on either V or H however you would lose 25 dB or more if someone did the same thing only had the antenna tipped the opposite way just like the difference between V versus H. No real advantage and some definite disadvantages to doing it. The best configuration is one antenna with dual polarity that can be switched. That way you are never more than 3 dB down from the strongest signal possible at any given time.

 

[Yeti Communications Ltd]

locally you will have some attenuation ....however in skip it will not matter as skip flips the signals polarity anyway in a random manner (kind of tumbles the signal)

 

[Mustang 131]

not sure if anyone has covered or had anytime to do this, but has anyone ever took lets say a Maco 103c ,104c etc....and placed it in between the H/V and did any tests..Just curious as if it would act as both or how the pattern would be.You always see it vertical, or you see it flat, but never in between....

It's better the horizontal for local talking. Vertically polorized antennas lose ground gain, so some dx gain is lost.

 

[Captain Kilowatt]

It's better the horizontal for local talking. Vertically polorized antennas lose ground gain, so some dx gain is lost.

People say this all the time but in practice it is not really true since the incoming skywave rotates polarity along the path. At any given time it is impossible to tell what polarity the incoming signal is. I ran a dual polarity beam for many years back in the 80's and even then the other station was using a single polarity antenna his signal strength would be better one minute when I was vertical and better the next minute when I was horizontal, The extra 5 dB or so of ground reflection gain is MORE than offset by polarity shift during propagation.

 

[wavrider]

In DX the only real advantage for horizontal polarization is less noise as most man made noise is vertical polarization.

Horizontal will be quieter.

 

[Road Squawker]

In DX the only real advantage for horizontal polarization is less noise as most man made noise is vertical polarization.

Horizontal will be quieter.

the TOA (and thus the ground loss) for a vertical and a horizontal beam fed at the same feedpoint height will be different.

Modelling results
In January 2008, —as little as three months before his lamented dead— L. B. Cebik, W4RNL (SK) published what was going to be the last entry of his seminal 10–10 News series.
It turned out to be an interesting gain comparison of single element 28.4 MHz antennas modelled over various ground types.
. His findings seem to fit well with what John Devoldere, ON4UN modelled and published for equivalent antennas on the lower HF bands.

Horizontal HF antennas
… benefit from nearby ground gain
At a height of about λ/2, the nearby ground reflection of a horizontal HF antenna will start to be constructive at interesting take-off angles for long- distance ionospheric contacts. This will provide a net gain over the antenna in free-space.

Vertical HF antennas
… suffer from nearby ground loss
This is not the case with vertical HF antennas. Nearby ground only contributes loss. This even more so when the ground forms part of the return path of the radiating structure.
Even when far-away ground reflections may cause the directivity of a vertical HF antenna at low take-off angles to be much higher than that of a horizontal HF antenna, its net gain will still be lower at those angles.
This makes the horizontal HF antenna a clear winner.

Note that gain and directivity are not synonymous; gain takes into account losses, directivity does not.


https://www.google.com/url?sa=t&rct...al/en/&usg=AFQjCNHpvyHi7ThHU18Og3UgU9dlWfNDSA

 

[wavrider]

the TOA (and thus the ground loss) for a vertical and a horizontal beam fed at the same feedpoint height will be different.

Modelling results
In January 2008, —as little as three months before his lamented dead— L. B. Cebik, W4RNL (SK) published what was going to be the last entry of his seminal 10–10 News series.
It turned out to be an interesting gain comparison of single element 28.4 MHz antennas modelled over various ground types.
. His findings seem to fit well with what John Devoldere, ON4UN modelled and published for equivalent antennas on the lower HF bands.

Horizontal HF antennas
… benefit from nearby ground gain
At a height of about λ/2, the nearby ground reflection of a horizontal HF antenna will start to be constructive at interesting take-off angles for long- distance ionospheric contacts. This will provide a net gain over the antenna in free-space.

Vertical HF antennas
… suffer from nearby ground loss
This is not the case with vertical HF antennas. Nearby ground only contributes loss. This even more so when the ground forms part of the return path of the radiating structure.
Even when far-away ground reflections may cause the directivity of a vertical HF antenna at low take-off angles to be much higher than that of a horizontal HF antenna, its net gain will still be lower at those angles.
This makes the horizontal HF antenna a clear winner.

Note that gain and directivity are not synonymous; gain takes into account losses, directivity does not.


https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0ahUKEwjd6d-8vZ_KAhUG3SYKHb6EB4EQFggfMAA&url=http://hamwaves.com/vertical-horizontal/en/&usg=AFQjCNHpvyHi7ThHU18Og3UgU9dlWfNDSA

OK Squaker, those are MODELING RESULTS ONLY,
I do agree modeling is a good way to predict the lobes, nulls and GAIN of antennas but it is ONLY a prediction.


ON4UN is also quoted in your posts, are we talking low band DX or 27 or 28 MHz??

Let's keep this in perspective, this is about an 11 meter yagi.

Mount an 11 meter vert on the ground, put an 11 meter yagi 1/2 wl in the air and of course the yagi has more gain.

Mount both at 1/2 wl above ground and you will be hard pressed to see any difference on the first or second hop of skip, the vertical will out perform the yagi on long distance multi hop nine times out of ten for TX but the yagi will be able to receive weaker signals due to gain being reciprocal,.

I have no controlled tests to reference as there is no control over propagation conditions.

 

[M0GVZ]

OK Squaker, those are MODELING RESULTS ONLY,

Backed up by almost a century of real world testing.

ON4UN is also quoted in your posts, are we talking low band DX or 27 or 28 MHz??

It is completely irrelevant as all dimensions are shown in wavelengths.

Let's keep this in perspective, this is about an 11 meter yagi.

Why does it matter, do they conform to an entire different set of physics than any other antenna for any other frequency?

Mount an 11 meter vert on the ground, put an 11 meter yagi 1/2 wl in the air and of course the yagi has more gain.

Mount both at 1/2 wl above ground and you will be hard pressed to see any difference on the first or second hop of skip, the vertical will out perform the yagi on long distance multi hop nine times out of ten for TX but the yagi will be able to receive weaker signals due to gain being reciprocal,.

You are talking rubbish and in the end of your last sentence you've even contradicted what you said at the start of it. Gain is reciprocal so if the yagi is able to receive weaker signals because of more RX gain then the station at the other end will be able to hear the Yagi over the vertical because the yagi has more TX gain.

Here you go - gain of vertical vs dipoles at different heights for the various angles of arrival for signals. The vertical is a 1/4 wave but a 5/8 wave only has an additional 2dB if you want to be picky. At all angles the vertical loses over the dipole 1/2 wavelength high. A Yagi would beat it even more comprehensively. You may argue the toss about it being modelling but modelling is very very accurate compared to real world use.

 

[Captain Kilowatt]

The bottom line is that gain is one thing and losses due to polarity differences are completely different. Saying that a vertical yagi is best for local and a horizontal yagi is best for DX is not accurate. Sure the majority of locals use vertical polarity as most have omnidirectional vertical antennas however the polarity of the incoming skywave signal is anything but what it was when it left the transmitting antenna. That is uncontrollable and having both polarities available on at least one end of the conversation can make all the difference in the world. Many times I would TX on one polarity and RX on the opposite just to maintain a contact as the polarity was constantly changing. As I said before, that additional 5-7 dB of gain from ground reflections is far more than offset by differences in polarity. Back in my big 11m days dual polarity beams were quite popular and everybody knew all this. Today however someone sees something on the internet and repeats it since it must be true since it was on the internet. Very few people seem to have the concept of what happens after the electrons leave one antenna and before they arrive at the other antenna. The reason I stack horizontal antennas is because I can stack more of them on the same tower not because of the extra few dB gain I might get. If I had my choice and money was no object I would have dual polarity beams for every band so that signals would never be more than 3 dB down from maximum. It's not the gain that makes the contacts as much as it is the losses that looses them.

 

[Henry HPSD]

On 11 meter DXing we are dealing with a thing called Faraday Rotation.

As soon as someone sees a large difference between a vertical and horizontal antenna. It is primairly NOT due to the polarisation but for most because the antennas have different take off angles or...there is a large difference in gain.

The faraday rotation is so fast there isnt a advantage in 'picking' a polarisation.
(google it)

There is however a large bennefit to be gained if one use a high horizontal yagi.
you will have more additional ground gain and when placed high (say above 1/2 wl) the take off angle will be lower...providing a better system for that long distance QSO.

Yes, there are always buts...take for example the Sproadic E propagation.
In such a case a relative high take off angle would be bennificial.
A low placed horizontal yagi could do this for example.
or...in such a case a vertical could outperform the high placed horizontal yagi.

lets put it other wise...think logical...on the higher HF bands..

What polarisation does the military use to contact the troops far away ?
What polarisation does the radio world service use to reach out to those on another continent ?
What do the the big contest stations use ? do they use vertical beams to get a higher score ?
etc....

With the above said....there are other situations where switching between vert/hor could help...in EME for example (there are other)

I always switch with antennas...including vertical polarisation.
I always switch with antennas...at different height....

This because i want to change my take off angle.
But in 99 percent of the cases the highest horizontal beams beats the rest for "real" DX..Especially now with the lower sunspots...and they will go futher down...
Each day i can still contact USA or Australia on 11.
That is done on the horizontal high yagi.

But.. is it wise to use several polarities...in some cases ..yes.. not because of polarisation...but due to the difference in take off angle.

for that remote DX contact...go horizontal as high as possible.

With the above said there is some information availible that in some cases circulair polarisation could come out on top .. when the band is just opening.
Dont think i need to tell what my project at this moment is ;-)

hope it was of use.

kind regards,

Henry 19DX348

 

[Captain Kilowatt]

I disagree with you Henry about the difference in signal strength being due to take off angles and not polarity. Faraday rotation may be a factor however having the ability to switch polarity from V to H or vice versa definitely DOES make a big difference sometimes. When one has a dual polarity antenna with both sets of elements on a common boom the difference in TOA between the two polarities is not significant enough to see several S-units difference in signal.

 

[Henry HPSD]

Hi !

Well..in all honesty, i had the same point of view in the beginning.
Sadly it was incorrect.

Attached a fast calculation..by all means.. not optimised to show maximum 'proof'..
but allready im seeing several S-units in take off advantage.

both antennas are the same on the same mast and boom ..one horizontal one vertical.
i didnt include a mast...

im afraid the difference in TOA is capable of showing such a difference.
with two antennas on one boom.
Bare in mind..im expressing the bennefit of the high placed vertical versus the deeper null off the horizontal.
.