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Slot antenna

 
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Kale
Antenna-Theory.com Newbie


Joined: 09 May 2011
Posts: 4

PostPosted: Mon May 09, 2011 5:14 pm    Post subject: Slot antenna Reply with quote

According to this website, the slot antenna behaves like a parallel LC resonant circuit. The transmission line is smaller than wavelength / 4 behaves like a inductor and the trantsmission line is larger than wavelength / 4 behaves like a capacitor.


Can we look at it in another angle? e.g. the current flows throung the boundary of the slot antenna and hence the inductance effect is created. The voltage difference between the upper and lower boundaries of the slot antenna created the capacitor effect.

Thank you for your kind attention.
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Schubert
Antenna Wizard


Joined: 08 Apr 2009
Posts: 161

PostPosted: Mon May 09, 2011 9:07 pm    Post subject: Reply with quote

Hmm....well, remember the slot antenna needs to have balanced inductance and capacitance to radiate.

So the circuit model diagram was that the short end (from the feed) looked inductive and the long end looked capacitive.

If you try to look at the slot as both inductive and capacitive, how can you get an intuitive feel for if they are balanced?

It's a good thought process though.
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Kale
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Joined: 09 May 2011
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PostPosted: Tue May 10, 2011 3:56 am    Post subject: Re: Slot antenna Reply with quote

Thank you for your favourable reply.

"So the circuit model diagram was that the short end (from the feed) looked inductive and the long end looked capacitive. "

So the overall circuit model diagram for the slot antenna is inductive and capacitive. They can be balanced if we change the dimensions of the slot.e.g. width which affects the capacitive effect or length which affects the inductive effect (if we look at the slot antenna in terms of the current and voltage rather than transmission line)

Is it correct?

Thank you very much.
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Schubert
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Joined: 08 Apr 2009
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PostPosted: Tue May 10, 2011 4:19 am    Post subject: Reply with quote

"They can be balanced if we change the dimensions of the slot.e.g. width which affects the capacitive effect or length which affects the inductive effect (if we look at the slot antenna in terms of the current and voltage rather than transmission line) "

- well, no. If you feed a slot antenna in the center, will it radiate at a half-wavelength? No. So there isn't a width you can change to decrease or increase the capacitance such that it radiates.

In general, the slot antenna radiates depending on it's perimeter. That is, you need roughly a perimeter of one wavelength to radiate (or a half-wavelength for a thin slot).
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