What would happen if you mounted a Vertical Omni-Directional Ntenna in a Horizonally?

[DualAntennas]

What would happen if you mounted a Vertical Omni-Directional Antenna in a Horizonal fashion? I.E. Paralell to the ground and Co-Phased it with a Vertically Mounted one?

Hummm?????? Anybody care to test this one??? he he he????

 

[The DB]

First off, just so you know, I don't think "cophasing" is technically the correct term for this... That being said that is coming from someone who does not like the term "cophasing" at all... Anyway...

You would get a rather different radiation pattern.

The horizontal plane would look like this...

And a vertical plane pattern that would look like...

Note the different colors, the red patterns would be horizontally polarized pattern, the blue patterns are the vertically polarized pattern.

A vertical half wavelength antenna mounted in exactly the same spot shows a gain of 2.76 dBi. These models show that such a setup here would at best give you a negative gain (or loss) of -5.3 dBi. A direct comparison to a single vertical half wavelength antenna over 8 dB in losses.

Modeling Notes: This model was made with a half wavelength vertical element on the Z axis with the base of the vertical element 5 meters high. Additionally there is a horizontal half wavelength element that starts at the same point that the base of the vertical element is and follows the positive X axis. The height of this entire element is 5 meters high. The two elements together would resemble an "L" in form. These elements are both fed independently and are in phase with each other, and are over 4nec2's default "real" ground.

And as you said above "he he he???"


The DB

 

[Captain Kilowatt]

First off, just so you know, I don't think "cophasing" is technically the correct term for this... That being said that is coming from someone who does not like the term "cophasing" at all... Anyway...

The DB

Thank you! If anyone ever looks at any of my posts where we are discussing more than one antenna you will notice I always use the term "phased antennas" or "phasing lines". The reason is simple. That is the proper term. There is no such thing as "co-phased" antennas or a "co-phasing" line. Those terms are long misused terms that seem most prevalent on 11m and nowhere else. Unfortunately like a lot of other terms constant and popular misuse has lead to general acceptance of it being fact. Just because it's popular does not mean it's right.

 

[The DB]

Generally I will use "phased array", or refer the two multiple antennas as being "in phase".

It is one of many words and phrases used almost exclusively on 11 meters that I don't really personally like, often by those who think they are in the know, or want to sound cool, or perhaps people who actually think those are the proper words to use for those setups.

The best part is when I don't use phrases like "two hotts" or "bounceback", instead choosing to use the actual technical term to describe what is going on and they are completely lost...


The DB

 

[Captain Kilowatt]

Generally I will use "phased array", or refer the two multiple antennas as being "in phase".

It is one of many words and phrases used almost exclusively on 11 meters that I don't really personally like, often by those who think they are in the know, or want to sound cool, or perhaps people who actually think those are the proper words to use for those setups.

The best part is when I don't use phrases like "two hotts" or "bounceback", instead choosing to use the actual technical term to describe what is going on and they are completely lost...


The DB

Yup I agree. I work with a bunch of guys that refer to the moving parts on an automatic stacking machine as a "platinum". The proper word is "platen" but what do I know. They have been there for as long as 30 years in some cases. I have just been there for 8 years. :headbangI don't bother to try and correct them and just keep calling it by it's rightful name whenever I have to mention it. My philosophy is criticize me when I am wrong not when I am right.

 

[DualAntennas]

What would happen if you mounted a Vertical Omni-Directional Antenna in a Horizonal fashion? I.E. Paralell to the ground and Co-Phased it with a Vertically Mounted one?

Hummm?????? Anybody care to test this one??? he he he????

Lets get back on topic here....

 

[Robb]

Lets get back on topic here....

Great explanation DB; but I'm afraid your answer went right over DualAntennas head.
Perhaps a simpler explanation is needed?

A vertical antenna is vertically polarized. When you place it horizontally, it becomes horizontally polarized. It might be the same antenna that came out of the box; but it will operate and behave differently depending on how it is oriented relative to the earth.

A vertical antenna receiving a signal from a horizontal antenna transmitting will be received weaker. The same is true the other way around. Because the radio waves emitted and received from vertical and horizontal antennas are different from each other. They are out of phase with each other by 90 degrees.

A horizontally polarized antenna is not going to work well for you if you want to talk locally to others that use vertical antennas. Unless they too have horizontally polarized antennas as well. Truck antennas are all vertically polarized antennas. If you are going to talk to others locally, chances are they have vertically polarized antennas.

So why would you bother to do that with two antennas; let alone one?

 

[Road Squawker]

Yup I agree. I work with a bunch of guys that refer to....

same here, I worked at General Dynamics in the "glass room", where we manufactured some really high end Mil Spec. CRT's.

we used a machine that employed a high voltage charge to activate the getter material.............


of course we all called the machine the Ghetto Blaster

 

[The DB]

Lets get back on topic here....

OK, sure. So are you looking for just a general conversation or do you have questions or perhaps expectations?


The DB

 

[The DB]

Great explanation DB; but I'm afraid your answer went right over DualAntennas head.

... hmm ... ok I'll try this another way...

With the setup you mention you gain the ability to talk to people using both horizontal and vertical antennas, however, there are performance costs for that benefit. For one, the signal strength between you and other vertical antennas will be noticeably weaker. Further, the signal strength for the horizontally oriented antenna will be weaker still.

A better option would be to have two center fed half wavelength antennas, a vertical and a horizontal, whose feedpoints are at the same point. This will still incur losses with the vertical polarization, but a significantly smaller amount at its worse point in the radiation pattern then any part of the layout you suggested. The horizontal element will have 10 dB of gain over the horizontal antenna in the setup you are wanting a discussion on in two directions, that is about a 10 times difference.

A still better option would be to have two separate antennas, a horizontal and a vertical, with a switch box to switch between them. It is a quicker and easier setup, and you don't have the performance costs of trying to run both at the same time. Long story short, there are better ways to implement a horizontal and vertical element, but none of them will work as well as a single horizontal and a single vertical with a switch box to switch between them.

The biggest problem comes with the "cophasing" as you put it. One thing this does is divide the power going to the antennas between the antennas, effectively cutting the power each antenna gets in half. Unless the antennas are set up in certain ways where the signals can benefit from each others presence you will always have losses. The signals from vertical and horizontal antennas "cophased" together will simply never be able to give you any real gain. You do gain the ability to talk to horizontally polarized antennas as well, however, but the cost for this "advantage" is pretty high even in the best of situations...


The DB

 

[vo1ks]

Crossed dipoles

Mounting two dipoles to create a X-shape. By adjusting the phase difference between the two it could create anything from vertical to horizontal. In between the two will be eliptical with varying portions in either plane. With equal H and V it will create circular polarization. If it were installed in a + shape, adjusting phase will create polarization from / to \ or circular.

This is quite common in FM broadcasting as well as amateur satellite communications.

If you were to look at the polarity of a received signal after multiple 'skips' through the ionosphere it will be switching in a somewhat random manner. An antenna that responds equally well regardless of polarity will suffer considerably less rapid signal fading. Direct ground wave signal strenght will be 3dB less compared to equal polarization.