0
$\begingroup$

I want to know about the directivity of thin dipole antenna of length 1.25λ for my assignment.Is there any formula related to its length?

$\endgroup$
  • $\begingroup$ Is it a trick question? $\endgroup$ – Phil Frost - W8II Feb 8 '17 at 18:42
  • $\begingroup$ @PhilFrost-W8II I doubt it; reads like homework. But yeah, $(1+\frac14) \lambda$ dipole... Anyway, we could change the question to read "given an $\alpha\lambda$-long dipole, can we derive characteristics like feedpoint impedance and gain based on $\alpha$?", and make it useful. $\endgroup$ – Marcus Müller Feb 9 '17 at 15:35
  • $\begingroup$ If you take your title question and put it directly in Google you will find some examples where this has been taught in schools. $\endgroup$ – SDsolar Feb 24 '17 at 4:00
1
$\begingroup$

I would imagine that by now, you have completed your homework. But for the sake of closing the topic, the directivity of a 1.25 wavelength, center fed (a very important qualifier!) dipole is ~3.27. Therefore the maximum possible gain is 5.15 dBi.

You can apply the general formulas for field at any distance from a center fed dipole and solve for the maxima. As they are rather lengthy, if you need the specific E or H field formulas, just post back as a comment and I will supply them.

$\endgroup$

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.