[NLRS] 10 GHz Beacon for Metro area

[Gerald]

On Sun, 2005-10-09 at 22:20 +0100, Donn Baker wrote:
> 
> At Breakfast yesterday, several of us talked about putting up a 10 GHz
> Beacon.  This is something I've been thinking about for some time.
> Interestingly, only some of the things _I_ thought necessary were mentioned
> by others.  Another instance of "N people, N+3 opinions !"
> 
> So, I'm going to start a "design process" for a 10GHz Beacon for the
> Minneapolis/St. Paul metro area.  I'm hoping that a number of you will have
> ideas and opinions valuable to the eventual construction and installation
> of the beacon.
> 
> Below is a first cut at a set of requirements for the Beacon.  Review,
> think about it, and make comments, please.  I'll collect the comments, and
> update the "design" more or less regularly.  After we've had a chance to
> think and talk about it, (maybe a month, by mid-November ?) we'll try to
> come to a consensus on what we want and need.  When we know WHAT we want to
> build, we'll get a design put together and review (mid-December;
> mid-January ?) it before we look for donations of equipment and volunteers
> to do the construction, testing, and installation.
> 
> The Aurora '06 meeting (4th Saturday of April) would be a good time to have
> the hardware available for "show and tell," with installation before
> Memorial Day weekend.
> 
> Comments ?
> 
> 73 Donn
> WA2VOI/0
> 
> 
> 10GHz Beacon - Mpls/StP Metro area
> 9 October 2005
> 
> OBJECTIVE:
> Provide:
> 	1)	A geographical locator/marker
> 	2)	signal for tuning/alignment
> 	3)	frequency standard
> 	4)	propagation indicator
> 
> MINIMUM REQUIREMENTS:
> Antenna
> 	Horizontal polarization
> 	Omni-directional
> 24-7 operation
> All-weather operation (i.e., winter/summer)
> Remote control 
> 	On/Off
> Transmission
> 	Modulation
> 		FSK ? CW ?
> 	Identification
> 		Call, 10 min, max
> 	Beacon
> 		sub-Grid square
> 		period of un-interrupted carrier, if CW modulation
> 		tone/dits
> >= 100mW TX output
> 
> ENHANCED REQUIREMENTS
> Frequency stability of <= x ppm
> 	where x:
> 	1ppm 	~ 10.4 kHz
> 	0.5ppm	~   5.2 kHz
> 	0.1ppm	~   1.0 kHz
> Multiple power levels
> Telemetry	
> 	temperature
> 	status

Getting stability good enough for a frequency standard is harder than
letting the beacon wander.

Typical beacons have used a Frequencies West block for simplicity and
they are known to wander, though there are versions that use external
oscillators that could be locked to a GPS signal or a frequency
standard. The FW block is easiest to key with a bit of FSK by simply
varying the supply voltage a bit.

Antennas are typically a multiple slot in waveguide, giving maybe 10 dBd
gain. I've thought cutting the 1/16" wide slots with an endmill can
require a large supply of endmills, copper being as gummy to machine as
it is. I'd rather cut most of the slots with a saw blade, but that tends
to make the outside and insides of the slots different lengths. There is
a volume of the MIT Rad lab series on beacons and I think that also
covers beacon antennas if not in the microwave antenna's volume.

I think there is a microwaver out east or west who sells such beacon
antennas. A search starting at G3PHO's page may turn up something, and
should turn up comments on beacons.
-- 
73, Jerry, K0CQ
Dr. Gerald N. Johnson, electrical engineer
All content copyright, Dr. Gerald N. Johnson