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Impedance transition from antenna to free space

 
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powerwave
Antenna-Theory.com Newbie


Joined: 26 Nov 2016
Posts: 2

PostPosted: Sun Dec 04, 2016 1:52 pm    Post subject: Impedance transition from antenna to free space Reply with quote

Hello,

I am puzzled by what happens at the interface between the antenna and free space. To avoid energy reflection, impedance matching must always be satisfied implying that the impedances must be the complex conjugate of the other. but the antenna electrical impedance is very different from the free space impedance (377 Ohm in the far field).

How do we prevent energy reflection with free space?
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admin
Site Admin


Joined: 03 Jan 2007
Posts: 204

PostPosted: Mon Dec 05, 2016 6:44 pm    Post subject: Reply with quote

No, this isn't valid.

Where would the energy be reflected to? You match the antenna to the transmitter/receiver and the energy is not reflected.
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helix
Antenna Theory Regular


Joined: 29 Jan 2015
Posts: 64

PostPosted: Tue Dec 06, 2016 6:42 pm    Post subject: Reply with quote

Powewave -- consider the difference between intrinsic impedance and characteristic impedance and this should resolve the apparent paradox.
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