ICAO HEX to Aircraft Reg

[Richard]

How about trying the F***M dipole antennas..... They are already tuned and ready to go. You could stick them to the window with a small suction cup. Here is the link, they have both the ADS-B and the 868 Mhz. Disadvantage is the price 

http://www.lxavionics.co.uk/collision-warning-systems.htm

[scsirob]

After a bit of detective work recently I noticed our Funkwerk Mode S transponder :

a) Transmits the ADS-B records just with no position info (but inc the flight ID (aka Reg) even with no ADS-B out connection, just ordinary mode S. These are picked up by PAW.

So, why not set your transponder to transmit Extended Squitter and feed a GPS signal? You'll show up with the big boys.

b) Does the above even if in STBY mode (which seems to just standby the squawk code emission.

I think that's an issue with SW version 4.5 or 4.7. You may want to check the service bulletins.

[ianfallon]

That's the plan - early days

[Ian Melville]

Would a short cable run between the PA unit and the aerial cause any serious drop in signal strength do you think?

Not much, but don't see much evidence that testers are using ground planes, which are an essential part of the antenna system. With a remote antenna it would be more important.

[stephenmelody]

Would a short cable run between the PA unit and the aerial cause any serious drop in signal strength do you think?

Not much, but don't see much evidence that testers are using ground planes, which are an essential part of the antenna system. With a remote antenna it would be more important.

Ground plates for which antenna? I understand it'll help the ADS-B side (but that's not a problem, airborne I can see planes up and down the whole country), would it help the ARF?

[Ian Melville]

Yes, but there are buts..

I am no radio expert, but did some experimental work with UHF antenna 35 years ago at Tec colledge. The reality is we need a 360 degree globe around our aircraft, which will be difficult to achieve, esp with only one antenna.
Assuming no blanking by aircraft structure. A vertical dipole would be the best option, at the expense of blind spots above and below us.
A whip antenna is in fact half a dipole, and requires a ground plane to make up the other half. There is a high risk that the antenna is not matched to the feed, and will in simple turns sap power from the signal, and possibly cause the TX section to overheat. Both can reduce range.
Ground planes will shape the signal. A horizontal flat plate will deflect the horizontal donut upwards, making you invisible to any RX below the plate. Using arms at 45degrees down improves that, but is still less than ideal.
A dipole in as clear air as possible or two whips, one above and one inverted below the aircraft would give the best coverage. Neither solution would be 'mobile'.

Sorry got to go to work now 

[Richard W]

I still wouldn't be able to get it on the coaming due to the slant of the windscreen. I've ordered 2 right angle adapters, I'll get them set up at home and see if there's any loss in using them.

I have the same rubber duck and a right angle connector, and the TX at least is good, the_top_pilot picked me up at > 5nm, although I received nothing.  I also aim to test against the supplied big antenna, when time permits.

[Richard W]

I have now tested the WirelessThings short 868 MHz rubber duck against the kit antenna supplied with the ARF.  The executive summary is that it is about 12 db down, so it's going in the bin.  Detail :-
Master, end fed kit antenna. Slave pigtail fed short rubber duck.  Master/slave test 30' apart in the open.
Slave RSSI -034 or -035, Master RSSI -033
Changed slave from small to kit antenna :-
Slave RSSI -023 or -024, Master RSSI -020

[Ian Melville]

Are the RSSI figure Decibels? I would be surprised if they were.