I recently purchased RTL-SDR v3 dongle along with antenna kit. I used 60cm each length and built vertical dipole antenna with boom length of 58cm and listened to airband frequencies.The closest airport from where i listen to is almost 15kms away. The audio received is with a lot of noise. Hence i have decided to build an antenna for permanent installation almost 30ft above ground.


2 Answers 2


It sounds like you are looking for an Elevated Ground Plane Antenna. A little large but doable at those frequencies. Search for Elevated Ground Plane Antenna Design. You can make one out of a SO-239 or an N-panel connector. I have made several, and they work well. Get it up as high as you can. Here is a link to get you started. Elevated Ground Plane Calculator

  • $\begingroup$ Did you mean SO-239? $\endgroup$ Commented Mar 20 at 21:56
  • $\begingroup$ Also, what materials? I used heavy solid copper wire for mine. $\endgroup$ Commented Mar 20 at 21:58
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    $\begingroup$ @Mike Waters Yes, that was my bad, fat finger typo S0-239. I use solid, bare #8 AWG copper wire. An antenna this size will need heavy gauge wire. The vertical and radials are roughly 28 inches long. $\endgroup$
    – Dereck
    Commented Mar 20 at 22:15
  • $\begingroup$ +1. The formula for a 1/4 ground plane and the radials is 234/MHz. Isn't 28" a tad long? $\endgroup$ Commented Mar 21 at 15:30
  • $\begingroup$ That online calculator is worthless. The antenna and radials should all be about 1/4 wavelength long. $\endgroup$ Commented Mar 21 at 15:34

I think it would be better to ask the community that "what kind of (omnidirectional) antenna could I possibly build to hear more stations and with less noise on the given band?" There are a lot of constructions with different gains and directional patterns, and I'm sure you can imagine where the limiting factors are: time, money, available space and restrictions to erect masts, etc.

Concerning the noises, there can be more reasons of that: the signal level of the station you heard was too low, this can be improved by an antenna with higher gain placed higher above the ground, or there are electrical noises near to you, whose are harder to eliminate if possible, or there are powerful out-of-band signals near to you that may deteriorate your receiver's sensitivity. It is not sure that you only have to upgrade the antenna.

The AM (modulation) that is used traditionally on the airband fequencies is prone to pick up many kind of noises (compared to, let's say, the FM), but it is the best if more than one station is transmitting on the same frequency at the same time even occassionally - they will not render the others unintelligible.


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