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Alan0354
Antenna-Theory.com Newbie
Joined: 21 Jan 2013
Posts: 5
Location: USA
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 Posted: Tue Jan 22, 2013 9:41 am Post subject: Confused about RHC and LHC antenna |
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For RHC circular antenna in tx mode at the origin radiating in +z direction, the unit vector is (x+yj)/sqrt{2}.
1) What if the same RHC antenna radiating on the +z axis, but back TOWARDS the origin? The unit vector should be (x-yj)/sqrt{2}.
2) Also, the EM wave radiated by the RHC antenna from +z back towards the origin is represented by (x-yj)/sqrt{2} also.
Am I correct? |
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bigSteve
Antenna Wizard
Joined: 14 Mar 2009
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| Posted: Tue Jan 22, 2013 11:47 am Post subject: |
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| Unfortunately some of this depends on convention, such as whether you are assuming time dependence of e^(i*2*pi*f*t) or e^(-i*2*pi*f*t) |
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Alan0354
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| Posted: Tue Jan 22, 2013 5:33 pm Post subject: |
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| bigSteve wrote: | | Unfortunately some of this depends on convention, such as whether you are assuming time dependence of e^(i*2*pi*f*t) or e^(-i*2*pi*f*t) |
Thanks for the reply. I am using the absolute convention of rectangle coordinates:
1) RHC implies thumbs point to direction of propagation which is +z in this case.
2) E =xcos(wt-kz) +ycos(wt-kz+pi/2). Which the unit vector becomes (x+yj)/sqrt{2}.
With this convention, a RHC wave travel at -ve z direction towards the origin should be E =xcos(wt-kz) +ycos(wt-kz-pi/2). Which the unit vector becomes (x-yj)/sqrt{2}.
Am I correct.[/code] |
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Alan0354
Antenna-Theory.com Newbie
Joined: 21 Jan 2013
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| Posted: Tue Jan 22, 2013 6:24 pm Post subject: |
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In fact this is the example from Antenna Theory by Balanis 3rd edition p78 to 79. I don't agree with the book. It uses spherical coordinates and I disagree with the assertion that the antenna transmitting from a distance from the origin towards the origin is (\theta +j\phi)/\sqrt{2}
Also for RHC antenna in tx mode using as receiving antenna at the origin, I agree with the given equation. But that would give total loss in reception!!! I am confused, please help.
Thanks |
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