How to make an antenna more directive by changing its physical size/scaling?

My current approach: I should make the antenna bigger. A directivity is a Fourier transform of illumination, distribution of the currents.

However, I'm not sure that my understanding and explanation are correct. Can someone help me to understand this question?

  • \$\begingroup\$ What configuration is the present antenna? What frequency range? what application? 'Making it bigger', in the sense of adding parasitic elements may work; but in the sense of making it longer, probably won't. \$\endgroup\$
    – Chu
    Aug 6, 2018 at 12:49
  • \$\begingroup\$ @Chu it is a common question, I have just read about the main antenna parameter and found some info in antenna-theory.com/basics/directivity.php. Here was suggested to determine directivity without math, only with a look on the picture \$\endgroup\$
    – user195287
    Aug 6, 2018 at 13:44

1 Answer 1


There are several ways to make an antenna 'bigger', all of which have the capability to improve the directivity if done correctly. In all cases, bigger dimensions, more potential directivity.

There's the Yagi-Uda technique, which makes it longer by adding parasitic elements in front of the emitter.

There's the reflector type, which adds a progressively larger reflective surface, either parabolic or trough, or an array of parasitic elements, behind the emitter.

There's the phased array type, which uses an array of (usually) similar emitting elements, with controlled mutual phase.


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