FlightAware Discussions

Hundreds to Zero: Bad Antenna?

I was tracking hundreds of planes at once with hundreds of km range and now…almost nothing. Barely a plane if any. Has anyone ever had their antenna fail?

I have the FlightAware antenna and have since April 2019. Been rock-solid since. Suddenly nothing going on. I’ve replaced the LNA, I’ve swapped SDR dongles, now I’m thinking it’s the antenna itself. I don’t know if extreme wind sheer could have snapped something or what, but it’s been a very windy fall in Iowa, and it’s on a 10’ high pole ontop of a 28’ house so…possible?

I’m likely going to buy a new one and try it but I’m annoyed and wondering if anyone else had the darned thing fail. :frowning: I miss my planes!

Think about the cable as well. You would not be the first having trouble due to a broken cable.

I was thinking the cable is worth checking too.
Either physical damage or it’s got a load of water in it.

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Update: So I finally pulled down the antenna itself and found that the gas discharge lightning arrestor was chuck full of water along with the connectors. Removed that from the line entirely and the planes are back! Kindof. They’re back on the screen but the range is REALLY low, like <100nm, so there’s still something wrong with the entire setup. I don’t know if that means more water infiltration or what but I need to poke at it more.

If you had water in the antenna connectors, it’s likely wicked into the coax. That will alter the electrical characteristics of the cable and could serious attenuate the signal. It’s also possible that it’s corroded the cable from within. You will likely have to replace it - I’ve seen cables in a marine environment corrode over a 10m or more length because of water ingress. Cut a short length off the exposed end and have a look at the copper inside. It tends to go black with water exposure.

To prevent it you need to use waterproof connectors or weather proof them some other way. I have my LNA inside a waterproof box that also protects the cable connections there. You could also pack them with silicon grease and wrap them with self-amalgamating tape.

What type of connectors are you using and what (if any) water-proofing have you used?

caius Damn, I wondered. I have some Coax sealant tape on the connections but it likely wasn’t enough (obviously). Thankfully the cable from the lightning arrestor to the LNA is a 10’ cable and not the 75’ run that heads down to the basement so replacing that one is a lot easier. I’ll get some silcone grease as well and pack things in as well as putting on better coax sealant tape.

geckoVN The order goes like this: FA antenna (N) to Lightning Arrestor (N) to 10’ cable to (SMA) RTL-SDR LNA in a waterproof box with drip loops to (SMA-to-N) 75’ LMR-400 to the basement to (N-to-SMA pigtail) to Nooelec SmarTee. As I said above, I had some tape on them, but likely not enough, especially for the week worth of downpours we got that probably soaked everything.

The N’s “should” be waterproof unless you’ve used crimp connectors.

Have you used self-amalgamating tape or ordinary PVC insulation tape?

This is what I’m using for sealing the connections; however, I probably did a poor job of some of those connections and that’s my fault: https://www.amazon.com/gp/product/B00A7AXBSQ

That’s the good type of tape - that should keep the water out if applied correctly.

Do your connectors look like this?
image
These are not waterproof.

An alternative is that the radome of the antenna is cracked and letting water into the cable.

Get some heatshrink with glue for the back side of crimp connector.

I’m quite a fan of the glue lined heat-shrink, but it doesn’t bond very well to a PVC jacket.
You are better off using sealed connectors to start with. (and making doubly sure with SA tape)