Is the impedance of an antenna infinite (since an antenna is an open circuit, with the ends bent opposite to each other), or finite (radiation resistance instead of an open circuit)?(adsbygoogle = window.adsbygoogle || []).push({});

The reasoning seems to be that an antenna is a transmission line terminated in an open circuit, so you get standing-wave currents (with a node at the ends). You can integrate the standing-wave currents in the formula for the electric field to get the total power-radiated, and from the total power-radiated you get the radiation resistance by dividing by the current squared.

But how should you view this radiation resistance in relation to the open circuit resistance of infinity? The only thing that makes sense is in parallel (if it's series, then infinite+finite=infinite), but then the transmission line effectively gets terminated by a resistance equal to the radiation resistance, so there is no longer a current node at the end so your assumption was wrong.

It seems that for impedance matching, people pretend that the load is the radiation resistance of the antenna rather than an open-circuit. But isn't reflection of the current-wave essential to the operation of an antenna to get standing waves in the antenna? - hence you can't have it so that no reflection occurs: there has to be an impedance mismatch.

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# Resistance of an antenna

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