Link budget: polarization loss

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Lupin

Joined: 22 Jan 2003
Posts: 326
Helped: 2

09 Nov 2007 15:27 polarization loss

Hi all,

I'm performing a link budget between two RHCP antennas.

Can anyone give me the formula associated to the polarization loss due to the different Axial Ratios of the two antennas?

For example, if satellite antenna is AR < 2 dB for every direction, if the ground antenna AR is between 0 dB and 10 dB, how much is value of the maximum polarization loss?

It can play a major role, so I have to consider it in the budget.

Thanks in advance for your cooperation.

Best Regards,

Lupin

Azulykit

Joined: 18 Feb 2007
Posts: 851
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Location: All over the Map.

10 Nov 2007 7:14 rss losses satellite linkbudget

My first thought was to suggest that you use the cosine of the angle between the axis of each but as I think about it more I would look at the projections of the orthogonal components of each to estimate the resultant loss. The question will take careful analysis to work out. Pozar has a reference devoted to polarization issues. You might want to run down a copy as I suspect the result will not be trivial or simple. He may have worked out the problem already.

vfone

Joined: 10 Oct 2001
Posts: 2328
Helped: 327

10 Nov 2007 16:43 rhcp linear polarization loss

http://www.cushcraft.com/comm/support/pdf/Antenna-Polarization-14B32.pdf

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Azulykit

Joined: 18 Feb 2007
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11 Nov 2007 7:54 Re: Link budget: polarization loss

I made a mistake when I said Pozar had a book on Polarization, The author is Warren Stutzman, "Polarization in Electromagnetic Systems" is the reference I intended to cite.

He does discuss, in around thirty pages, the coupling between antennas with various polarization states. His analysis includes several techniques to get the result you are seeking. The easiest looks like a device called a "Ludwig Chart". Apparently Microwave Journal published an article on the subject: Vol 19 Sept 1976 page 63. (as well).

For the cadre of people who have to ask: No, I do not have an e-book on the subject.

Lupin

Joined: 22 Jan 2003
Posts: 326
Helped: 2

13 Nov 2007 20:34 Re: Link budget: polarization loss

vfone, the linik u provided is for linear and circular polarized antennas...

I need the polarization loss between two RHCP atnennas.

Azulykit, Where can I fonr the book u mentioned?

Thanks for your support,

Lupin

Azulykit

Joined: 18 Feb 2007
Posts: 851
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Location: All over the Map.

13 Nov 2007 23:03 Re: Link budget: polarization loss

There are several places. My bookshelf is one. I just did an internet search and found a number of places where you can obtain a copy. It is published by Artech. You could probably find a copy in a University technical library. I wouldn't think that it would hard to find a copy to purchase. The ones I saw were on the order of $100, no surprise there either.