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How does a quarter-wave dipole operate?
If a half-wave antenna is the shortest resonant length of an antenna, then how can a quarter-wave antenna function effectively?

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4 Answers

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Quarter-wave monopole antennas actually use a ground plane to ‘complete’ the other half of the antenna - so it still operates as if it were a half-wave resonant antenna. This means that a quarter-wave antenna should occupy a smaller footprint on a circuit board. It’s for this reason that they’ve become the most popular form of embedded antenna.

If you take a 916MHz application, a full-wave antenna would need to be just shy of 330mm long. A quarter-wave version would only need to be 87.2mm long. Surface mounted antenna manufacturers can coil this up across multiple layers, but they still require a ground plane of this length to operate as the other radiator. Without a ground plane of one quarter of the wavelength, the antennas efficiency would be compromised and to an even greater degree when operating at lower frequencies.
answered by
This question is answered by attending lectures at the university or by reading professional books. If you ask Google about it you will also get an answer.
answered by

How large of ground plane (mm2) is needed?   Is there a formula based on frequency?

answered by
Will using the ground plane cause any problems with radiated emissions?

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