FlightAware Discussions

Antenna cable advice requested


#1

I’ve been running a Pi3 in the attic with the attached FA antenna for some time. But I think I have a place I can put the antenna outside that, based on a quick check, will have good reception and not invoke the ire of the HOA. What I’d like to do is sneak a flat cable through a window (raise the window, pass the cable through, close the window; I’ve done this with flat Ethernet cables). Is it possible to do this successfully with an antenna cable? I’m ok if there is a small degradation in signal as a result. Ideally I’d like it to be up to 20’ or so. If this can be done what type of cable and connectors would be required. Obviously I know nothing about this so thanks for any help.


#2

Use this under the window:

Then RG6 for you nearest Walmart store on each side of the window to the end points.

There will be losses, but it’s still better than being offline.


#3

Thank you, I’ll look into that!


#4

Oh yes, for adapters…you’ll need an N male to F female, and F female to SMA male.


#5

Come in via a roof vent maybe? Be sure to come in from the low side of the vent otherwise water will follow the cable into the attic.


#6

I’ve got the flat cables on order. I’ll dig through my stash and see if I already have any of those adapters.


#7

Suggest you try the flat cable in-place with your existing setup before going to the effort of rearranging everything - there can be a lot of loss at 1GHz, which might outweigh any benefit from moving the antenna


#8

Here are some good low-loss cables: https://smile.amazon.com/gp/product/B00H9II8Q4

Just remember that to get low loss in coax cables at 1090 Mhz, 1.090 GHz, takes a thick cable, size matters.


#9

Hi
I use this cable with adaptator


#10

I don’t trust at all those flat cables, at 1GHz frequency. I am curious to see what results will get the new setup, when replaced in place.


#11

Inside the flat protective jacket is a short length of RG174 or similar.
I used to use a few for VHF and up, with one on a satellite feed (~1GHz).
The short length means it ‘shouldn’t’ cause too much degradation to the system.


#12

Probably depends on how hard you smash the coax with the window.


#13

image

The one below is not good

image

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#14

That is my experience with the copper colored version, too, it did not really work very well at all.


#15

When squashed in a window, all signal will be shorted and grounded through the capacitance formed between conductors and metallic window sill.

image


#16

Should had installed PVC (or wood) window sills :smiley:


#17

Yes. It ‘does’ need to be treated appropriately.

Yuck - never seen that sort. It’d be ok for AM broadcast, but not much else.

Your saying it’s not suitable for people living in trailer parks?


#18

As the OP I thought I’d follow up with my results after finally receiving the flat white coax and misc connectors to put everything together. I did a few experiments. First placing the antenna outside connected with the minimum cable (the SMA from the receiver to the FA antenna). I used that as the baseline. I then used the flat coax with 3’ of standard coax as the minimum possible for that approach.

Results: for grins I tried placing the antenna horizontally and that worked as expected (poorly). I then placed it vertically as planned using just the SMA cable. With that as a baseline I replaced installed the flat coax/coax combination without moving the antenna. The result was slightly worse - about a 10% loss in messages/second. Since this combination gave me more length I then raised the antenna 3’ compared the to SMA-only solution and it really made no difference (i.e. still about 10% fewer messages/second). For more grins I then switched back to the SMA-only solution and lowered the antenna 3’ below the original placement. This did make a noticeable difference compared to the first attempt. Note: I did not smash any cables in the window during testing.

I’d say all the results were as expected. While doing this I realized I had one window where I could place the antenna just outside, fairly inconspicuously, using only the short SMA cable. So that is the solution I’ve adopted (at least for now).

My original objective was to remove the solution from my attic and get it in a more climate-controlled location that includes smoke alarms etc (i.e my objective wasn’t to increase range). Since every day is different I can’t tell how the current installation compares to the attic. For sure it isn’t wildly different but I did give up about 6’ in height. Also, in the attic the antenna had only the wood/shingles between it and open air - in the current location it has a window/house on the west side. From looking at the current plane sightings I believe that, as you’d expect, I’ve lost some coverage on the west side. I may have lost a bit on the south as well (too soon to tell). So I imagine over time I’ll see this location is worse from a coverage standpoint (again, as you’d expect). To place the antenna higher up on the house would require longer coax and way to pass it through the window or wall. I expected I’d lose some coverage that way as well. Short of being willing (and getting it past the HOA) of mounting the antenna in open air at the very top of the house I think I’ve got a reasonable result. I might try a second receiver on the west/southwest of the house at a later date (I’ve got the older Pi I used for FA originally). Even in the attic my coverage to the west was always unexpectedly sparse.

Thanks for the advice above.


#19

I have recently moved my antenna far away from my house (where the Pi and tuner dongles are), so I have used 150’ (46 m) of pre-terminated RG6 cable with two change-over connectors (SMA to F) and one preamp at the antenna. I was a little greedy with the length, I have some extra loops in the attic, but is better than the alternative.

Results are great even with that long cable, mainly because I am compensating the cable loss by raising the signal at the antenna.