Move my RPi, antenna cable, and antenna higher – except that the RPi will be more exposed to the elements (hotter?) – and might destroy my plans to add some weather sensors to the RPi since it will no longer be shaded properly
Anyways, adding a 5 meter antenna cable extension will help me to get higher, but will this be cancelled out by signal loss?
P.S. My RPi is currently sealed inside a plastic coffee container, so it won’t get ‘wet’ no matter where I move it.
RG-58 signal loss isn’t great, at 1GHz it’s something like 65dB/100m. So a 5m extension will lose you something like 3dB (+ connector losses) - i.e. 50% of the signal. (It’s not as bad as it sounds, but you will probably lose your weakest signals)
For comparison WF100 (commonly used for satellite installs around here) is around 20dB/100m @ 1GHz. Something with that sort of loss would probably make the extension more feasible.
DItch the RG-58 and go with a good 75 Ohm satellite cable, such as RG-6 or WF100. It’s cheaper and has far lower signal loss. F-style connectors are also easier to work with. Remember that you need to make the connector at the antenna watertight, such as by using self-vulcanizing tape covered with a good electrical tape (Scotch 88), or enclosing the whole thing to keep out the elements.
I’m rapidly coming to the conclusion that folks are much better off using RG-6 style cables for ADS-B unless they’re RF freaks and/or will be transmitting along the same or close-by cables. 50 Ohm cables for 1 GHz that are low loss are expensive, hard to handle, and use expensive connectors.
The R820T dongle has 75 Ohm impedance as do power injectors, Satellite LNB amplifiers and so on that we often use - we might as well go to 75 Ohms up by the antenna and run the whole down feed at that impedance.
It would be good if antenna, amplifier and filter designers also realised that most of the people using this stuff for ADSB are amateurs with a limited budget that they are willing to spend on this - and designed everything with a small budget in mind (make it 75 Ohms, ditch the SMA and N connectors in favour of the easy to fit F-connectors.
The limited budget is the reason the Pi + R820T + SD card reciever has taken off so well, it’s low cost and some result is almost guaranteed.
I used RG-6 because of the price. My run I have from the antenna to my USB dongle is only around 12-14 feet long if that. So I don’t have to worry about a long run… But here is the Spec for what I was.
You got it right ! RG6 and F connectors are widely available and inexpensive. Then, if you want power injection and amplifications, you can buy standard F connector satellite supplies off the shelf at great prices. I like the compression style connector for rugged service but the silicon gel filled crimp on style will also prevent water entry.
Also, antenna construction is dirt cheap using RG6. But, I have to say adding a N to F adaptor to the Flight Aware antenna provides an industrial strength, really high performance antenna system (looks good and compact).
By the way I use twist on F connectors [get the ones that match the cable diameter … same supplier] and wrap with self amalgamating tape - no tools required beyond a craft knife
Them the next experiment would be a satellite amplifier ebay.ca/itm/220750618448 (would need an female-female F barrel connector) and a power injector - Someone in Canada will advise what is available and inexpensive there
I’ll have the FA antenna and a run of about 3 feet to my dongle…then a 12 foot USB cable to my laptop. So antenna, N to F connector, professionally made RG-6 to F-MCX adapter to dongle. This will replace a spider 4 leg and 35 feet of RG-6. Hoping for more range but in reality I just want to see if it works better. Filter next (when FA is shipping).
my run to the antenna is about 35 feet from the dongle and i’m getting hits in the 180-240mi arc (or so the stats page tells me) on a homemade collinear. i’m not sure what my loss is but i’d say don’t be terribly discouraged to use a long run to your setup.
So what is the max run of RG6? Bought an antenna and going from F to coax. Have some good quality RG6 (about 50 feet). Tried it out and picked up NOTHING on the antenna. Plugged the little mini that FA recommended way back when and “ding,” everything came back up.
My setup - everything 75 ohms - running satisfactorily:
SYSTEM 1 (65 ft Coax, With Amplifier, Maximum Range 250 nm)
Home made indoor antenna (8 element open top CoCo with F connector) >> 15 ft cheap quality RG6 Coax >> RCA Satellite amplifier 18 dB >> Home Made Power inserter >> 50 ft cheap quality RG6 Coax >> 20 inch RG316 pigtail F to MCX >> DVB-T Dongle inserted directly into RPi Model 2 >> 6 ft network cable from RPi to router.
SYSTEM 2 (10 ft Coax, No Amplifier, Maximum Range 250 nm)
Home made indoor antenna (Cantenna with F connector) >> 10 ft cheap quality RG6 Coax + 20 inch RG316 pigtail F to MCX >> DVB-T Dongle inserted directly into RPi B+ >> 15 ft network cable from RPi to network switch (network switching hub) >> 15 ft network cable from network switch to router