One for the aerial gurus.
I'd like to run my SBS and/or RadarBox with a directional antenna so that the box predominantly picks up traffic in one direction - in my case to the east, which would cover LHR arrivals and departures.
Does anyone have any suggestions for either an off-the-shelf directional antenna or for how I could suitably screen my existing omnidirectional aerial to achieve the same result ?
MTIA
Dave
Hi Dave,
I am using a FLU-SR/Y13 from BAZ. Excellent construction with good performance.
http://www.amateur-radio-antenna.com/professionalantenna/aeronauticalantenna/index.php (http://www.amateur-radio-antenna.com/professionalantenna/aeronauticalantenna/index.php)
Cheers,
Peter
This will probably do the job Dave - at least it's not too expensive.
When I was considering a new antenna myself a couple of months back, I seem to recall a bit of discussion about it on a couple of the other forums.
http://www.nevadaradio.co.uk/avionics/moonraker-high-gain-1090mhz-
Thanks, guys.
The other option I was thinking of, since I need directionality but not really any extra gain, was to use the existing aerial with a DIY screen to suppress signals from unwanted directions.
Any suggestions for a suitable design ? I'm thinking a section of plastic guttering wrapped in tinfoil, but that's not very elegant :-)
Perhaps a bit OT, but if some bright spark out there could come up with a very basic, very simple and very cheap SMA switcher, it might prove a useful bit of kit for many of us.
(Two antennas feeding in to a switch which would allow manual selection of the preferred single feed to the RB)
I would have thought a small directional beam antenna would do the job for you especially as you want directivity rather than gain. 4 odd directors, a simple dipole and a reflector. I can't remember what the spacing is off hand but I can look it up. It doesn't need to be perfect as you are only receiving on it.
By the way - dustbin lids make good parabolic reflectors and would screen you present antennae nicely!
Coax switches are easily available at amateur radio outlets such as W&S.
J.
Love the dustbin lid idea ! :-)
http://www.airnavsystems.com/forum/index.php?topic=4739.0 (http://www.airnavsystems.com/forum/index.php?topic=4739.0)
Quote from: Mike_Tassy on May 19, 2010, 10:46:29 AMhttp://www.airnavsystems.com/forum/index.php?topic=4739.0 (http://www.airnavsystems.com/forum/index.php?topic=4739.0)
Thanks for that, although I'm not sure my DIY skills are up to it !
Cumulus
Any chance of a screen grab of your polar patern using a yagi antenna?
Quote from: Cumulus on May 19, 2010, 07:50:07 AM
Hi Dave,
I am using a FLU-SR/Y13 from BAZ. Excellent construction with good performance.
http://www.amateur-radio-antenna.com/professionalantenna/aeronauticalantenna/index.php (http://www.amateur-radio-antenna.com/professionalantenna/aeronauticalantenna/index.php)
Cheers,
Peter
Polar diagram available on BAZ website. I use the yagi when mobile for EGLL ground movements at a distance of 25nm. Gives a 30% increase in ground targets compared to an omni.
http://www.polarorbiter.co.uk/YagiMobile.jpg (http://www.polarorbiter.co.uk/YagiMobile.jpg)
Cheers,
Peter
Sorry for the late reply, Moonraker now do a yagi for 1090mhz sells around the £50 mark.........
RADAR-SKYSEARCHER 1090MHz DIRECTIONAL ANTENNA
Type: 1090MHz High Gain Directional Antenna
Frequency TX: 1090MHz
Frequency RX: 980-1200MHz
TX Gain 14.5 dB
Power: 50W Max
Impedance: 50 Ohm
Dimensions: 490 X 200 X 180mm
Mounting Masts up to 5.6cm (2")
Socket: SMA Female
Weight: 0.45Kg
This antenna is designed to be used for the increased reception of Radar Mode-S and ADS-B signals on 1090MHz. It is a brilliant directional antenna for AirNav Systems RadarBox and Kinetics SBS-1er Pocket Radar
Manufacturer: Moonraker
Model: 11-571
Price: £49.95
regards
iain 2M0VVS
Thanks for that - as it happens I currently have on of those on loan for evaluation (I'm not sure I'd describe it as a Yagi, though).
Dave to many reflectors to be a "normal" aerial :)
hard to describe though !
iain 2m0vvs
Thats a parabolic reflector!
J.
Quote from: Jeremy on May 25, 2010, 06:24:25 PMThats a parabolic reflector!
Too late, I've just worked out how to attach it to my barbecue ...
...prompted by this and other threads I thought I would try and build a 1090 tuned Yagi just to see if it would work ( I know nothing about antenna design)! A minimal amount of research turned up a piece of Yagi design software (John Drew DL6WU Yagi design). I plugged in the numbers, rooted round the tool shed, and 30 minutes later had a prototype built out of plastic curtain rail and some 4mm aluminium rod, all stuck together with a glue gun. To cut a long story short I hung this out of my loft window, pointing north, at the same height as my baseplane antenna but about 5 m away from it. I was surprised with the results, firstly that the thing worked at all ;-) and secondly with the resulting max range polar diagram (2 hours) - doesn't seen very directional. I compared this with my baseplane polar and thought mmmm I need to do some more research: firstly to understand how the thing worked, and secondly to build a second prototype based on this!
Attached are images of the two polar diagrams and an image of the first prototype.
I think it needs a bit more time to create a better p diagram. The yagi will give a low angle lobe to the N and some gain off the back to the S. There should be deep nulls E and W. If you look carefully they are there. Think of the polor diagram of the yagi in 3G so you will need a/craft at all heights to build up a true picture. Nice work.
J.
Thanks Jeremy, I can see that now - should have left it a bit longer. However, the prototype is, at this very moment, being recycled to produce a more robust version based on information from the huge knowledge base on the web. Oh dear - a new hobby is emerging ;-). I'll post the results....
Bewarned - the more time you spend making these things the less time they stay up or work! J.
I think you may be right! But I did make another, and the preliminary result is displayed below. At one stage had about 136 flights returning and I tracked a flight into East Midlands to about FL85. I was a bit more careful with the measuring and mounting of the elements. Made the boom out of 20x20mm wood this time too. Quite what TOM436 is doing there I don't know ;-).
Very good. It shows the front and back lobs and the smaller ones at 45 deg and 315 deg very nicely and deep null at the sides.
Spot on!
J.