Replacement ADS-B Aerial

[stumblingtrout]

Hi All,
I bought a Pilot Aware recently but broke the small aerial when the unit was in my bag. I found it's probably the most vulnerable component on the device.
I purchased a new 1090mhz SMA ADS-B aerial on Amazon and I'm seeing many magnitudes more traffic on Sky Demon.
My question is this - being fairly non technical, is there likely to be any drawback to what I have done?
Many Thanks,
ST

Pictures:

[exfirepro]

Hi ST and welcome to the Forum.

In effect, what you have done is replaced an 'untuned' 'broad band' antenna which was not 'tuned' to 1090 MHz with one which is tuned to 1090 MHz and also has a little bit of 'gain' (the 5dBi bit printed on the antenna). This is why the level of displayed traffic has increased significantly.

The signals being received by the 1090 MHz side of PAW come from powerful transponders or ADSB Transmitters (outputting 100 to 500 watts at the transmit antenna), so are readily received at long distances. Increasing the receive gain of these signals is unlikely to have a significantly detrimental effect on PilotAware, though due to the way PilotAware processes alerts from Mode C or S aircraft, it may result in these occurring when the aircraft are a bit further out than expected, though this can be compensated for by using a shorter Mode CS Detect Range.

Just a word of warning though. The P3i signals the other antenna is broadcasting (and listening for) are much weaker at only 500 milliwatts (1/2 a Watt), so the position and orientation of that antenna is significantly more critical. Both antennas should in practice be oriented as near to vertical as possible to minimise signal attenuation due to cross polarity.

Best Regards

Peter
(PilotAware Engineering)

[Ancien]

ST
I can see several drawbacks.

You have paid a lot for something that you don't need.
It's much too big to hang in the cockpit.
When you are flying you will not be interested in transponder traffic more than a few miles away ( unless of course you will be exceeding the 250 kt limit below 10000)

You have a lead that connects to this new antenna. Cut the end off and remove the coaxial sheathing for 69 mm from the end. Stiffen it up with heat shrink and Hey Presto one excellent 1090 antenna.
You could do it with your broken antenna lead - nothing to lose - a small plastic sucker will hold it to the window.

I certainly wouldn't strap it to the PAW antenna.

This works in my aeroplane in the hangar, picking up passing mode C and very distant ADSB with no trouble. In the air its very unobtrusive.

God luck and remember KISS

[Ian Melville]

Agree with Ancien, the closeness of the two antennae could degrade the abilities of the P3i antenna.

Rather than cutting the cable in the picture, cut the antenna off the original ADSB antenna then do as Ancien suggests. Costs very little as my stiffener was a scrap snake tube from an R/C Model. Photo of my effort attached. You will then have a spare short cable if you want to put everything in a Stratux case

Oh, and performance was up on original antenna, getting hits from 500Km away when flying at 3000' 

[PaulSS]

is there likely to be any drawback to what I have done?

By using small tiles you've made the floor quite busy and by not levelling them with the step you've created a bit of a tripping hazard.

Sorry 

[stumblingtrout]

Haha!! I'll see if the guy that built the house in 1826 is still knocking about so I can complain ;-)

Thanks for the comments - positioning in the aircraft isn't an issue, I mount the PAW on the side portion of the windscreen in the Cessna 172 that I'm training in using a universal smartphone suction mount and then the battery pack sits nicely in the storage pouch down by my legs with the bundled power lead. Keeps everything in an ideal position

I was impressed with the OGN last week, spotted a glider at our altitude heading towards us over Grafham Water before we had visual. 

I might give the current set up a go then this weekend - and see what happens. If I have issues I'll follow some of the suggestions on here. I'll be mindful to keep the P3i antenna pointing up, perhaps I should angle the 1090mhz one downwards so it's not sitting right against it...

[exfirepro]

I might give the current set up a go then this weekend - and see what happens. If I have issues I'll follow some of the suggestions on here. I'll be mindful to keep the P3i antenna pointing up, perhaps I should angle the 1090mhz one downwards so it's not sitting right against it...

Sounds like a good plan to me! Pretty sure all will be well, though antenna separation is always good.

Regards

Peter