Directional Mode S antenna ?

[DaveReid]

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

[Cumulus]

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

Cheers,

Peter

[bratters]

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-

[DaveReid]

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 :-)

[bratters]

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)

[Jeremy]

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.

[DaveReid]

Love the dustbin lid idea !  :-)

[Mike_Tassy]

http://www.airnavsystems.com/forum/index.php?topic=4739.0

[DaveReid]

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 !

[Dean]

Cumulus

Any chance of a screen grab of your polar patern using a yagi antenna?

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

Cheers,

Peter

[Cumulus]

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

Cheers,

Peter

[iain5968]

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

[DaveReid]

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).

[iain5968]

Dave to many reflectors to be a "normal" aerial :)

hard to describe though !

iain 2m0vvs

[Jeremy]

Thats a parabolic reflector!
J.