1
\$\begingroup\$

This question is derived from certain answers I received for a previous question I posted.

Case : Let's say I have two GSM antennas of the exact same shape, design and material. The only difference is that one is 10 times larger in size than the other.

Question : What sort of impact would this have in the second antenna's directivity & gain?

\$\endgroup\$
  • \$\begingroup\$ I'd check the data sheets for the detail. \$\endgroup\$ – Andy aka Oct 8 '14 at 14:05
2
\$\begingroup\$

The shape very much affects how the size will play.

For the simple case of a dipole antenna, the best performance (in terms of power transfer) will be obtained with half the wavelength of the signal to be transmitted or received. You also get local minima in the impedance for values of \$k \lambda + \frac{\lambda}{2}\$, and increasing lambda will mean more directionality on the main lobe(s) but also more side lobes. Shortly put, it can be worse and typically \$\frac{\lambda}{2}\$ is the best.

If you have a more directional antenna like the yagi, the size will be primarily influenced by the main folded dipole , and the reflectors and directors will be sized accordingly. But a larger antenna may mean more directors (usually the reflector is one) and therefore, again, more directivity.

For other antennas like the parabolic reflector, size can improve gain/directionality but the benefits will get progressively lower.

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.