1090 mhz antenna

Status
Not open for further replies.
Joined
Feb 23, 2018
Messages
3
Hi
I have a 1090mhz antenna with sma male connector. Is it possible to use a T sma for using antenna for two device? One device is a radarbox(receiving aircraft info) another is an ads-b dongl. I want to use dongle for receving airband freq. Is all possible?
 

mtindor

OH/WV DB Admin
Database Admin
Joined
Dec 5, 2006
Messages
8,761
Location
Carroll Co OH / EN90LN
Hi
I have a 1090mhz antenna with sma male connector. Is it possible to use a T sma for using antenna for two device? One device is a radarbox(receiving aircraft info) another is an ads-b dongl. I want to use dongle for receving airband freq. Is all possible?
It's possible, but it would be very foolish.

1. 1090 mhz ADSB already requires a good antenna system
2. Using a T to split the signal will halve the signal to each device (or worse)
3. You will pick up very little airband traffic with a 1090 antenna

If you can't devote a separate antenna / antenna system to your dongle / airband receiver, I'd recommend not even bothering with it at all. It would be futile to use the 1090 antenna for airband traffic, and if you use the T you will pick up very little / no planes on ADSB or audio on airband.

mike
 
Joined
Feb 23, 2018
Messages
3
It's possible, but it would be very foolish.

1. 1090 mhz ADSB already requires a good antenna system
2. Using a T to split the signal will halve the signal to each device (or worse)
3. You will pick up very little airband traffic with a 1090 antenna

If you can't devote a separate antenna / antenna system to your dongle / airband receiver, I'd recommend not even bothering with it at all. It would be futile to use the 1090 antenna for airband traffic, and if you use the T you will pick up very little / no planes on ADSB or audio on airband.

mike
Thanks mike. So about the antenna, if i shorten my ads-b antenna cable from 10 to 2 meters. Do you think it help increase range too much, for example two times increase?
 

Ubbe

Member
Joined
Sep 8, 2006
Messages
5,816
Location
Stockholm, Sweden
You didn't tell us what cable you are using. If the cable attenuate 3dB it will reduce the reach of the antenna by 25%. If it attenuates 6dB it will only reach half the distance to the airplanes. If you use an antenna amplifier the lenght and quality of the coax doesn't matter and you can also split the signal if you want to without any problem.

Coax Attenuation Chart

You can build your own antenna if the one you have now isn't the best one.

https://www.balarad.net/

If you don't use any filters it might be possible to receive some airband 118-136MHz traffic if you use an amplifier to overcome the antennas missmatch at those frequencies. SDR dongles are easily overloaded by strong signals and if you want to focus on airband you can use a 118-136MHz filter to improve reception.

https://www.ebay.com/itm/Airband-AI...-Excellent-rejection-SMA-M-SMA-F/282688071569

/Ubbe
 
Joined
Feb 23, 2018
Messages
3
You didn't tell us what cable you are using. If the cable attenuate 3dB it will reduce the reach of the antenna by 25%. If it attenuates 6dB it will only reach half the distance to the airplanes. If you use an antenna amplifier the lenght and quality of the coax doesn't matter and you can also split the signal if you want to without any problem.

Coax Attenuation Chart

You can build your own antenna if the one you have now isn't the best one.

https://www.balarad.net/

If you don't use any filters it might be possible to receive some airband 118-136MHz traffic if you use an amplifier to overcome the antennas missmatch at those frequencies. SDR dongles are easily overloaded by strong signals and if you want to focus on airband you can use a 118-136MHz filter to improve reception.

https://www.ebay.com/itm/Airband-AI...-Excellent-rejection-SMA-M-SMA-F/282688071569

/Ubbe
Thanks, i use coaxi think is rg-58
 

dlwtrunked

Member
Premium Subscriber
Joined
Dec 19, 2002
Messages
1,062
You didn't tell us what cable you are using. If the cable attenuate 3dB it will reduce the reach of the antenna by 25%. If it attenuates 6dB it will only reach half the distance to the airplanes. ...
/Ubbe
In addition, the earth is not flat. The earth's horizon is more a limiting factor than sensitivity once sensitive enough. Once one can receive signals from aircraft at 40,000 ft limited by the earths horizon, additional gain does not buy you greater range. (This amounts to something between 200 and 300 miles if the earth were perfectly round.)
 

Ubbe

Member
Joined
Sep 8, 2006
Messages
5,816
Location
Stockholm, Sweden
Yes, if you already log airplanes 300km away you do not need to do anything for ADS-B signals, but RG58 attenuate 7dB for 10 meters and 1,5dB if you can reduce it to 2 meters. If you change to RG6, that are much cheaper than RG58, and still use 10 meter it will attenuate 2dB, you will double the range.

If you look at the links there's a comparison (picture below) what happens with a missmatched antenna when you add the amplifier, something you probably will need to use if you want to pick up the airband and split the signal from the same antenna without sacrificing any ADS-B performance.

/Ubbe

 
Status
Not open for further replies.
Top