Best cable for aerial extension

[DaveL]

Hi all, I am researching into permanently installing a PilotAware in an EV97 and intend to put both aerials in one side as we have a transponder aerial in the other. I would like to customise the aerial extensions to length and I need advice what extension cable to use.
I found the following web page: http://www.arrg.us/pages/Loss-Calc.htm
and Input my requirement (2M long extension, 870MHz and 0.5W) and tried RG-174,RG-58, RG-8x, RG-8 and LMR-400.
It was a bit scary to see that you lost nearly half the signal if you use RG-174 but I found that RG-8 and LMR-400 were the best.

No 1 - Am I going over the top and worrying too much about line loss??

No 2 - Would it be practical to use either RG-8 or LMR-400 for an aerial extension in an aircraft?

I also intend to fit the aerials as far apart as practicable on the metal plate between the wing and body, is this good practice?

Dave.

[Ben Smith]

I have no experience of RG8, LMR400 is great stuff and I use it for any long runs on ground stations, however for your purpose it is far too thick and stiff, for shorter runs have a look at H155, it is much thinner and reasonably low loss, it should be fine for the distance you are proposing.

[exfirepro]

Hi Dave,

Have you read these two documents:

http://www.pilotaware.com/wp-content/uploads/2016/10/PilotAware-Antennas.pdf

http://www.pilotaware.com/wp-content/uploads/2016/12/161205-Permanent-Installation.pdf

Yes, fitting your antennas as proposed should give excellent results.

For very long coax runs we normally suggest RG8X, which is slightly thinner than RG8, but SMA connectors for RG8X are difficult to obtain - only available from the USA and it won't be particularly easy to fit in an aircraft.

At the sort of length you are talking about, loss won't be too critical, especially for the 1090MHz receive side, but as you are obviously aware you need to be more careful for the P3i side due to its much lower power levels. PilotAware Hardware www.pilotawarehardware.com sell pre-assembled 3 metre extensions with SMA connectors. These use a fairly thin coax, which is fine at that length and being flexible, easy to route. I'm not sure what the coax 'type' it is but Dave, who runs PilotAware Hardware should be able to tell you via the Contact link on the site. Replacement SMA connectors for that type of coax are fairly readily available on eBay if you need/want to shorten it. Remember you will also need a crimping tool, such as  https://www.maplin.co.uk/p/coaxial-connector-crimping-tool-a38qw to attach them.

With regard to antennas, you can use PilotAware tuned monopole whips (tuned to 869MHz) for both frequencies (they are close enough for 1090MHz receive due to the high strength of the signals), though you need to make sure they are carefully waterproofed at the connection to the coax connector and they MUST be fitted to metal bodywork or with a suitable metal ground plane (as described in the Permanent Installation Document). Several users get good results using these antennas. Other antennas specifically designed for external use on aircraft at 1090MHz and 868MHz (Flarm) are of course available but at much higher cost.

Hope this helps.

Regards

Peter

[Biker]

Hi all,
I am in this same situation as Dave regarding fitting PilotAware to an Ev97. I have searched the internet and found the H155 cable, SMA connectors and crimpers to make up the extension leads but it appears a bit excessive to have to purchase a tool that I will only use once. Does anyone know of a company that could make up the leads for me to reduce the overall cost.

Best Regards.

Biker.

[PaulSS]

https://www.gigatronix.co.uk/cabulator/coaxial/cable-type

[Biker]

Hi all,
Many thanks for the link to Gigatronix, as they did not have H155 cable selectable on their website I called them and talked to a very knowledgeable person who suggested LBC240 extra flex and priced up two leads at a total cost of £44.
I priced all the parts from wifi-shop24 for H155 coax, and including shopping and a crimping tool (€16/£14) it came to €43/£39.
So unless anyone knows of a better option I will order the parts from wifi-shop24 and add the crimping pliers to my tool kit.
PS it will be available for hire for the cost of a pint😀😀 excluding shipping.