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Element7k
Joined: 07 May 2003
Posts: 388
Helped: 8
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 19 May 2003 17:24 Vertical and Horizontal Polarisation of an antenna |
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What is the best way to determine the polarisation of an antenna? Please suggest ways to do this for all different kind of antennas. E.g. wire, square/rectangular/arbitrary patch, mircostrip, etc.
Cheers,
Element7k
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eirp
Joined: 11 Dec 2001
Posts: 807
Helped: 9
Location: Phase center
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| 19 May 2003 19:42 Re: Vertical and Horizontal Polarisation of an antenna |
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| Element7k wrote: |
What is the best way to determine the polarisation of an antenna? Please suggest ways to do this for all different kind of antennas. E.g. wire, square/rectangular/arbitrary patch, mircostrip, etc.
Cheers,
Element7k |
Dear Element7k!
First you can look at the direction of electric currents flowing on the antenna. You can guess, if you're experienced, or simulate given antenna.
If you need to be sure, you must look more at current animation (polarization can be mixed (non pure) or circular!) - or compute radiation properties of antenna. Polarization of E-vector is determined by direction of electric currents (look for vector potentials in some antenna handbook).
If you measure the antenna, I refer to any antenna book - search for polarization elipse.
Eirp
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Element7k
Joined: 07 May 2003
Posts: 388
Helped: 8
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| 20 May 2003 0:04 |
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Dear EIRP,
Thanks for answering my query.
When you say electric currents, do you mean do you mean the E-field?
How can you tell he polarisation of the antenna from the "currents" on the antenna? What other parameters can you tell from the currents animation?
When measuring the antenna, is it logical to take 4 planes measurements (2 planes with a vertically polarised tx antenna) & (2 planes with a horizontally polarised tx antenna) Then conclude if the AUT is horizontally or vertically polarised (if it is a linear antenna) by taking the pair when the highest rx power reading is found? What is to be done if I do not know if this antenna is linearly or circularly polarised antenna?
Appreciate any help.
Cheers,
Element7k
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Kit-the-great
Joined: 30 Mar 2002
Posts: 174
Helped: 1
Location: Russia
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| 20 May 2003 9:53 |
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Dear Element7k !
I'm venture to take part into discussion.
On 'currents' in antenna technique usually means the currents in Huygens-Kirhgoff integral (so-called radiation integral). It is also can be 'effective electric currents' (for ex. in the aperture of horn antenna) and makes a sense of 'aperture field distribution'. For radiation pattern calculation it is unimportant what do You integrate: currents or E-field on closed surface.
About a polarization: I'm not quite understand a problem: do You know the antenna construction or not ? Or You must determine the polarization only by radiation pattern measurements ? EIRP was absolutely right when tells You to view the (calculated, of course) currents (that must be 3D complex vector generally), it's can give You principal information about the antenna polarization type. The accurately results can be obtained after integration of this currents to compute the radiation pattern. It's concerned to any antenna type (wire, patch, reflector etc.).
Best regards,
Kit-the-great
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Element7k
Joined: 07 May 2003
Posts: 388
Helped: 8
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| 20 May 2003 18:49 |
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Hi,
everyone is welcome to join in the discussion. The more the better, that way I understand better:D
I gather that the electric current might be what is called surface currents in CST MWS? I have attached an animated gif of a patch with 2 slots in it. I was wondering if anyone can tell me how can I obtain the polarisation of the antenna from this animation?
@ Kit question, I do have the geometry of the antenna. But it is an electrically small antenna of random shape. Therefore, like what eirp has highlighted, I have to find the polarisation of the AUT by simulation or by measurement. I want to know if the antenna is horizontally or vertically polarised or if circular, RH or LH circular polarisation. So I want to know the best method of finding out the polarisation using either of this 2 methods.
Cheers,
Element7k
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