Feed cable length

[lawnmower]

I have USB ADS-B dongle with standard DVB-T antenna that came with the dongle. I got pretty good 80-90nm range even if the antenna was located at my (concrete) balcony. Then I made my own 8-part colinear antenna and positioned it outside my balcony and connected it to my dongle with about 7-8 meters of coaxial cable. I was thrilled to see the results but all I got was lousy ~40nm range.

So now I'm wondering that how long can the feed cable be from colinear antenna to USB dongle (without amplifier)? I could try to move dongle closer to antenna with longer USB-cable.

Of course there is also possibility that my antenna is broken, I'll have to measure the antenna again. I could of course check what happens if I connect DVB-T antenna to the end of my coaxial line mut I don't have suitable connector.

[thebenchmark]

From what I've read making a good coco can be very difficult.

A simple way to test the loss you're having is to extend the usb cable and minimize the coaxial cable if you see an improvement you'll see the loss the cable has.
Although I think 7-8 meters of good quality coax wont do that much to your range...

[VE6CPP]

Cable Loss at 1090Mhz can be quite high unless you are using a 'good quality cable'.. LMR400, etc. Replace your co-linear with your DVB-T at that location, and see if it makes a difference..if it Rx better than the original 80-90nm..then you will know your co-linear has either a bad connection between segments, is out of phase..ie; not cut properly for 1090Mhz. Building 'Better Antenna's..Luv's it ! Good luck
VE6CPP
F-CYQL1