This is an incredibly basic and stupid question, but, I'd appreciate someone explaining to me like I'm five years old a bit about antenna theory and why something that I'm doing is yielding horrible results.
Setup: I recently purchased a RadarBox AirNav ADS-B 1090 MHz antenna, which is rated for outdoor use, but, I need to use it indoors (I live in a block of flats, but, have flight-path facing floor to ceiling glass walls which have not interfered with other scanning hobby activities (more on that in a moment)).
The specs say:
Gain 7dBi, Impedance 50Ω±5Ω, Vertical Polarization
66 cm / 26 inch Vertical Antenna.
And it comes with 30 feet (9.1 meters) of cable, terminating in an SMA, which I plug directly into my RTL-SDR. That's on a Raspberry Pi, running dump1090-mutability, and a few software-feeding apps for flight tracking software.
I suspect the problem I have is going to come down to the cable, but, let's see what you all may say.
The core problem is that even though I've put the antenna right up against the glass wall, I'm barely seeing any traffic - which is in sharp contrast to the tiny and questionable quality antenna that came with the RTL-SDR USB stick several years ago.
With the RadarBox/AirNav, I'm seeing a max range of about 6 nautical miles for aircraft.
With the default antenna, it's not brilliant, but, it's out to 60nm.
These ranges are based upon RadarBox's software being calibrated for my exact GPS location and using the ADS-B data from transmitting aircraft.
Given that I have to do this indoors, I'm happy enough with that sort of value.
A voice in the back of my head is telling me the problem may be the 10 meters of cable that I have on the floor. The actual distance between the antenna and the RTL-SDR is about 1 meter, if even that, and I wonder if having the cable either doesn't enjoy the looping it has to do to fit in the space I have available, or, if there's just too much signal loss over that distance (which seems unlikely, given that it's meant to be this long and, obviously, positioned outdoors on a mast).
There's nothing coating the glass, and, as I mentioned, the small/crappy antenna does quite well.
Any thoughts about this would be appreciated. I used to know more about the engineering/science here than I do now (30+ years ago), but it's just not something I've used in a long time.
Thanks!
Setup: I recently purchased a RadarBox AirNav ADS-B 1090 MHz antenna, which is rated for outdoor use, but, I need to use it indoors (I live in a block of flats, but, have flight-path facing floor to ceiling glass walls which have not interfered with other scanning hobby activities (more on that in a moment)).
The specs say:
Gain 7dBi, Impedance 50Ω±5Ω, Vertical Polarization
66 cm / 26 inch Vertical Antenna.
And it comes with 30 feet (9.1 meters) of cable, terminating in an SMA, which I plug directly into my RTL-SDR. That's on a Raspberry Pi, running dump1090-mutability, and a few software-feeding apps for flight tracking software.
I suspect the problem I have is going to come down to the cable, but, let's see what you all may say.
The core problem is that even though I've put the antenna right up against the glass wall, I'm barely seeing any traffic - which is in sharp contrast to the tiny and questionable quality antenna that came with the RTL-SDR USB stick several years ago.
With the RadarBox/AirNav, I'm seeing a max range of about 6 nautical miles for aircraft.
With the default antenna, it's not brilliant, but, it's out to 60nm.
These ranges are based upon RadarBox's software being calibrated for my exact GPS location and using the ADS-B data from transmitting aircraft.
Given that I have to do this indoors, I'm happy enough with that sort of value.
A voice in the back of my head is telling me the problem may be the 10 meters of cable that I have on the floor. The actual distance between the antenna and the RTL-SDR is about 1 meter, if even that, and I wonder if having the cable either doesn't enjoy the looping it has to do to fit in the space I have available, or, if there's just too much signal loss over that distance (which seems unlikely, given that it's meant to be this long and, obviously, positioned outdoors on a mast).
There's nothing coating the glass, and, as I mentioned, the small/crappy antenna does quite well.
Any thoughts about this would be appreciated. I used to know more about the engineering/science here than I do now (30+ years ago), but it's just not something I've used in a long time.
Thanks!
