Distance from roof-mounted dis-cone antennae to box

[apjwright]

Hi.  I am a brand new AirNav radar box user, needing help with my roof mounted antennae.

I have a dis-cone antennae mounted on the roof of my house which has a rather-long run to where my PC is (approx 120ft).  After testing with both the supplied antennae and my roof-mounted antennae, the # of flights picked up by my roof-mounted antennae was far less.

Any ideas as to ways that I could improve the performance using my roof mounted antennae?

Thanks,
Tony
near YYZ

[Spaice]

Dis-cone antenna is designed to cover a wide section of the radio spectrum and is therefore useful for scanners, however if you like to listen to airband for an example you would be better off with an antenna designed to opperate in the 108-140mhz. The same for your radarbox the frequency coveres I believe is 1109 mghz, the antenna supplied by RB is designed to receive at his frequency only with no compromise unlike your Dis-cone,

[Spaice]

correction, the antenna for the RB is designed specifically to receive at 1090Mhz not 1109Mhz as stated in previous e-mail.

[Allocator]

Out of interest, I tried my scanner discone antenna too - all the aircraft disappeared!

No, it's got to be the standard RB antenna or another specifically made for Mode S signals - accept no substitute :-)

[apjwright]

Thanks for the responses.

Now the million dollar question.  Do I roof-mount the RB antenna and again deal with a long-cable run?  Thoughts & tips welcomed.

[Allocator]

A long cable run at RB frequencies is always going to be bad news.  High quality low-loss cable is the way ahead if you want to go this way, but cost and diameter of cable is always going to be a compromise.

Remember that height of antenna isn't everything here, just as long as the antenna is clear of obstructions.  I spent ages playing around with antenna's, only to find that the standard RB antenna on the roof of the car out in the open, worked exceptionally well!

What I would recommend, is installing RB on a laptop and using it with the standard antenna in a number of different locations.  You might just find a "sweet spot" that doesn't need a long cable run.  Don't forget to use the antenna on a metal groundplanes, or at least on the metal "CD" groundplane that comes with RB.

Whatever you do, do reset the polar diagram each time and leave RB running long enough to see what the coverage is like.  You can then take a screenshot of each polar diagram to compare later.

Whatever you do, have fun :-)

Allocator

[JimK]

I've been here.

I have a WIMO 1090 Antenna. I also use the mast amp. The run of cable between the Antenna and the RB is about is about 60 meters. The orginal plan was to plant all this on the roof.

However after significant testing using the Wimo mounted on a 20meter portable mast I actually get too many  messages around 1100 per second. So that's 60m of cable a WIMO 1090 amplified. Switching off the mast amp takes the # messages down to around 900 messages/sec.

The challenge is that my laptop just starts to hang.

With the above setup and the mast set to around 6 meters I'm getting 630 messages/sec.  which can be around 170-180 aircraft. I might add I live near Heathrow s by default will get a bit of traffic.

The reason for mounting  on the roof was to get better visibility of the Heathrow Traffic. Currently I lose sight of traffic (mast at 6m) when it goes below 400-500 foot.

Don't know if any of that helps.

Jim

[dudbaker]

Take a piece of coax.  Remove about 6 to 7 CM of outer cover.  Pull the braid down over the outer cover.  You now have an antenna.  Weather proof it.  Put plug on the other end and stick the antenna nice and high.  This is a dipole with the braid acting as a ground plane.

[Allocator]

Nice and simple, but I'd be surprised if you got results as good as the standard RadarBox antenna.

[richardj]

Any chance of selling extra Radar box antenna? as it really takes same beating, attached to a surplus and adapted sat nav window suction mount, mounted on my PVC facia, it's great but I'm left without an antenna if I go mobile.

[dudbaker]

Hi Allocator

Presumably your can see the results of my antenna if you look at Stansted.  You will see aircraft down to runway height of 350 feet.  If the transponder is left on I can see them on the landing and takeoff run.  Off course they are blue on the runway and red and green otherwise.  With the supplied attenna I loose them below 1000 feet.  Height and in the clear are all important.

[Allocator]

Dudbaker,

I'll take a look!

If you antenna is really working that well, it's going to make my GBP 110 BS-1100 look expensive :-)

[dudbaker]

Allocator

I am sure your antenna will be a good long term investment.  My comments were aimed at people who like experiment.  I see lots of memers put them in the loft.  My experiments have indicated that 1090 mhz does not like tiles.  The imoptant things are:  Antenna lenght, height and in the clear.  Then look at the gain from from professional antennas.

Dudley 

[Allocator]

I'm with you Dudley, I like to experiment with antenna's, especially if it doesn't cost anything :-)

I might just give your idea a try this weekend, I've got a few lengths of co-ax in the shed.  You are absolutely right about height and being in the clear.  People spend a load of money on a professional antenna and a pre amp, then run miles of cable to the receiver :-0

I actually got sent my external antenna by mistake - I ordered another magnetic antenna for my SBS-1 and got the BS1100 sent in error.  I suppose that I really should have sent it back .................

[pjwood123]

I am not bright enough to experiment, added to which I have constraints imposed by the building in which I live. There is no doubt that the standard RB antenna sitting in the window gives a much better response than the SBS antenna and SBS box.
I have concluded that I need an external antenna and would like comments on the following 3 questions if possible please:
1) I will have about 10 metres of cable to run, Westflex I know is best but is not practical for various reasons, will W 103 be an acceptable alternative?
2) I have read a lot about various antennae can anyone give comments on RadarRama vs Radar Extender vs Kinetic BS 1100 with high gain whip?
3) Will a masthead preamp such as Elad add a lot and is it a lot of hassle to install, or is there a preamp like the Jim that is specific to 1090 GHz?

I am up to stripping a bit of coax like dudbaker suggests, will this give a better response than the RB antenna if I just hang it out of the window? - sorry I realise it's 4 not 3 questions.