Airport - Discone Antenna
Hi Mike:
A couple of thoughts / ideas to ponder.
First, a Scanner Discone type antenna generally has very low 'gain' as most (not all) are used in 'wide-band' configuration, allowing us to receive lots of freq's across the spectrum. So that's a key factor in many cases. Also, many Discone's (again not all) are situated in the 'horizontal plane' as reference to earth, so more on this later....
Next, you are getting aircraft Comm's (aircraft side) due to the height (above MSL) of the aircraft on approach or in transit at higher flight levels, etc...So they are basically "sending down-wards" if you will the signal, so you will almost always hear more Aircraft than a Tower or Approach /Departure Comm's.
The Tower(s) often have a much lower output power and are transmitting in the vertical plane (relative to earth) as are the Aircraft 'blade antenna' systems.
So what I would recommend is a few 'location test' with your gear to ensure the antenna, coax, connectors and radio are working. If the radio will work via 12-vdc car battery / adapter take it out to several areas around the airport and see what you can pick up on a busy weekend or or other time that has a lot of air traffic...etc...
Then, slowly work you way out-wards from the airport area, and see when you start losing the Tower or check if the Airport has an 'automatic terminal forecast' that is updated hourly / as required that transmits continuous. You will need to search the RRef database to get the proper freq(s) for ATIS or the like in your area if available.
As always, you might try another antenna, with a Vertical 'cut' to the 118~136 am range if that is a primary interest. The antenna at 1/4 wave should not be an issue and I have home-brewed using old Radio Shack CB antennas (no loading coil) and 'cut' them down to a desired freq range....
As always, double check the connectors, coax and such and hope this gives you a few ideas....
Thx
Bill