gliders+radar

"Martin Gregorie" wrote in message
...
Big John wrote:
Mike

Make one for pennies and few Oz vs 2.2# and $139.95.

I did a search for info about Luneberg Lenses - found plenty of
definitions/explanations/units for sale but nothing on DIY Luneberg, how
to make a ball with a radially varying refractive index or sources of
materials with suitable refractive index gradations.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

A corner reflector is easy and effective...

http://www.westmarine.com/webapp/wcs/stores/servlet/producte/10001/-1/10001/142806/0/0/radar%20reflector/All_2/mode+matchallpartial/0/0

If you make one out of foam core board and aluminium foil, be sure to keep
all the angles at 90 degrees. The overall shape can be whatever you want.


--
Geoff
The Sea Hawk at Wow Way d0t Com
remove spaces and make the obvious substitutions to reply by mail
When immigration is outlawed, only outlaws will immigrate.

Ian wrote:
On Fri, 21 Jul 2006 04:47:04 +0000, Mike Schumann wrote:

Would the MTI also filter you out if you had a Mode C transponder?

Yes, it can do, depending on the settings of the filters. We had this
problem with the ATC at Cape Town International in South Africa.

There was a problem with Mode C Transponder equipped gliders flying in
wave, disappearing off the radar screens. The problem was found to be due
to speed filters in place on the equipment. Worse still the controllers
had call a technician if they wanted the filters adjusted. As I understand
the filters were set to filter out aircraft taxing on the ground at low
speed.

The local pilots and the controllers are now aware of the problem and the
radar has since been upgraded so this problem is under control.

But the problem is worth knowing about if you have a transponder in your
glider.

I'm not aware of this being a problem the USA. As I understand it, the
taxiing problem can be dealt with by by using proximity and altitude
filters, not speed filters. I'm told there are places where aircraft
squawking the VFR code (1200) may be filtered out, such as the Los
Angeles airspace, but these (very few) places are not where we are soaring!


--
Change "netto" to "net" to email me directly

Eric Greenwell - Washington State, USA

www.motorglider.org - Download "A Guide to Self-launching Sailplane
Operation"

Capt. Geoffrey Thorpe wrote:
"Martin Gregorie" wrote in message
...
Big John wrote:
Mike

Make one for pennies and few Oz vs 2.2# and $139.95.

I did a search for info about Luneberg Lenses - found plenty of
definitions/explanations/units for sale but nothing on DIY Luneberg, how
to make a ball with a radially varying refractive index or sources of
materials with suitable refractive index gradations.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

A corner reflector is easy and effective...

http://www.westmarine.com/webapp/wcs/stores/servlet/producte/10001/-1/10001/142806/0/0/radar%20reflector/All_2/mode+matchallpartial/0/0

If you make one out of foam core board and aluminium foil, be sure to keep
all the angles at 90 degrees. The overall shape can be whatever you want.


--
Geoff
The Sea Hawk at Wow Way d0t Com
remove spaces and make the obvious substitutions to reply by mail
When immigration is outlawed, only outlaws will immigrate.


Indeed. They've been discussed here in the past.

I think a Luneberg is not omnidirectional because the side with the
reflector on it will block incoming signals from that side, hence the
natty marine three-ball unit that gives 360 degree coverage. If I'm
right, you'd need to add another two balls (facing up and down) for
omnidirectional reflection.

OTOH a "spherical" corner reflector made from three equal sized disks of
of coreboard set at right angles (hence forming eight corner reflectors)
should be omnidirectional and probably lighter too.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |