Transcript The 10 GHz Flyswatter experiment - Craig Young

North
W5HN
Texas
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10 GHz Flyswatter Antenna
Experiment
Craig S. Young, KA5BOU
[email protected]
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The Problem
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• No Room at the Inn!
– And still missing
2304/3456 loop yagis
• Feedline Loss at 10
GHz
• I Don’t Climb
– Want access to
transverter
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Potential Solutions
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• Roving
– Great when the weather
cooperates
– Enhancements don’t always
coincide with roving times
• “Flyswatter” arrangement
– Well documented by W1GHZ
• MUD Paper
• Website
• Recent QST Article
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Flyswatter?
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Actually, a Periscope
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• An antenna configuration in which the
transmitting antenna is oriented to
produce a vertical radiation pattern,
and a flat or off-axis parabolic reflector,
mounted above the transmitting
antenna, is used to direct the beam in
a horizontal path toward the receiving
antenna. Note: A periscope antenna
facilitates increased terrain clearance
without long transmission lines, while
permitting the active equipment to be
located at or near ground level for ease
of maintenance.
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Performance Analysis
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• Estimated performance at 10 GHz
– Courtesy W1GHZ Excel Spreadsheet
PERISCOPE ANTENNA GAIN CALCULATOR
W1GHZ 2000
ENTER INPUT PARAMETERS HERE:
Frequency
Dish diameter
Flyswatter Aperture
Height (reflect. Spacing)
10.368
0.6096
0.76
12.192
Suggested flyswatter =
0.8
GHz
meters
meters
meters
Note: 1 meter = 3.28 feet
meters - for this height and frequency
READ FINAL RESULTS HERE:
System Gain
Dish Gain
"FEEDLINE" equivalent
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34.3
33.8
0.5
dBi
dBi
dB (effective gain of periscope over dish)
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System Design – Top Reflector
Texas
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1 ¼” Angle Iron
¾” Angle Iron
• Designed to mount to Rohn 55
Tower (17” leg center-to-center)
• Includes rung hooks for easier
installation
• Clamps to tower legs
32”
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Fly Swatter on the Ground
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System Design- Dish Mount
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32”
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Dish Mount on the Ground
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Elevation Control
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• Used a TVRO actuator for control with a Winegard DM4000 for feedback.
– Actuator uses 12VDC – polarity changes direction
• Integrated Az rotor controller and Elev control into single
chassis with room to add future polarization controller
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Flyswatter Controller
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Complete System
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“First Light”
Texas
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• NT5NT Beacon
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Recent Activity – Aug UHF Contest
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• Of course, there were
only 2 10GHz entries
from NTX
– KA5BOU
– NM5M
• Both with same 10
GHz score!
– Congrats, Eric!
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Recent Activity – Jan VHF Contest
Texas
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• Worked W5LUA and WW2R Direct
– Once we found each other in frequency!
– 3 and 6.4 miles, respectively
• Worked NM5M and WA5VJB via rainscatter
– 16.5 and 40 miles, respectively, via direct path
– However, was working off storm near Red River
• Approx 100 mile path to Eric
• Approx 120 mile path to Kent
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Issues
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• In traditional dish installation for
terrestrial work, elevation and
polarization are fixed
• More Degrees of Freedom!
–
–
–
–
Azimuth
Elevation
Azimuth
Elevation
Polarization
Frequency
Polarization
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Issues
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•
•
•
•
Alignment – Base to Reflector
Pointing Resolution
Elevation
Polarization
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Alignment
(base to reflector)
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• “1001 uses for a laser pointer”
– #907 – use it to find the center of the dish mount
relative to the center of the flyswatter
– Mark cross-hairs on base
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Azimuth Pointing
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• Resolution of current rotor controller is 6
degrees
• However, every time I “tap” the meter face, the
needle moves +/- 6-12 degrees!
• Currently, I “get it close” with the meter and then
fine-tune visually against the yagi-array
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Azimuth Pointing
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Elevation Issues
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• Winegard unit appears to be not 1:1
– I set it such that 45 degrees on readout is 45 degrees
actual elevation using protractor/level – resulting in
zero degree elevation of beam (at the horizon)
– However, flat down (storage position for least wind
load) is 9 degrees on the readout
– Highest elevation reads 63 degrees, but is actually
closer to 70 (didn’t measure)
– May be where I have sensor mounted relative to
flyswatter pivot point
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Elevation Issues (cont’d)
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• One degree of flyswatter tilt = 2 degrees of
beam tilt!
50º
45º
70º
0º
Beam=2(Elev) - 90
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Elevation Issues (cont’d)
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• Higher flyswatter tilt = loss from spillover
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Polarization
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• Either dish or feed must rotate with flyswatter to
maintain correct polarization
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Polarization
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• 180 degrees of swing required on dish-end to
maintain correct polarization
– Must be synchronized to flyswatter
• Current polarization control via “armstrong”
method
Angles in this half have
equivalent polarizations
in opposing half
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Next Steps
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•
•
•
•
•
Sun Noise Measurement?
Experiment with Other Bands
Permanent Dish Mount with Radome
Finer Resolution Az Control
Another 10ft?
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Sun Noise?
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• What is lowest elevation for good sun noise
measurement?
• Given current geometry and assuming max
flyswatter can be rotated in elevation is 65º,
highest beam can be steered is 40º
– Is this high enough?
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5760 Analysis
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PERISCOPE ANTENNA GAIN CALCULATOR
W1GHZ 2000
ENTER INPUT PARAMETERS HERE:
Frequency
Dish diameter
Flyswatter Aperture
Height (reflect. Spacing)
5.76
0.6096
0.76
12.192
Suggested flyswatter =
1.1
GHz
meters
meters
meters
Note: 1 meter = 3.28 feet
meters - for this height and frequency
READ FINAL RESULTS HERE:
System Gain
Dish Gain
"FEEDLINE" equivalent
26.7
28.7
-2.0
dBi
dBi
dB (effective gain of periscope over dish)
50’ run of LMR-600 would have approx 3.6dB loss
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Texas
3456 Analysis
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PERISCOPE ANTENNA GAIN CALCULATOR
W1GHZ 2000
ENTER INPUT PARAMETERS HERE:
Frequency
Dish diameter
Flyswatter Aperture
Height (reflect. Spacing)
3.456
0.6076
0.76
12.192
Suggested flyswatter =
1.5
GHz
meters
meters
meters
Note: 1 meter = 3.28 feet
meters - for this height and frequency
READ FINAL RESULTS HERE:
System Gain
Dish Gain
"FEEDLINE" equivalent
18.4
24.2
-5.8
dBi
dBi
dB (effective gain of periscope over dish)
My current plan for this band is a 12’ Directive Systems loop yagi
(25.2 dB) at tower top (61’). Assuming 70 ft. of LMR-600
(~5dB/100’), total system gain would be 21.7 dB
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24 GHz Analysis
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With 2 ft dish
With 1 ft dish
PERISCOPE ANTENNA GAIN CALCULATOR
PERISCOPE ANTENNA GAIN CALCULATOR
W1GHZ 2000
W1GHZ 2000
ENTER INPUT PARAMETERS HERE:
Frequency
Dish diameter
Flyswatter Aperture
Height (reflect. Spacing)
24.192
0.6076
0.76
12.192
Suggested flyswatter =
0.5
GHz
meters
meters
meters
ENTER INPUT PARAMETERS HERE:
Note: 1 meter = 3.28 feet
meters - for this height and frequency
READ FINAL RESULTS HERE:
System Gain
Dish Gain
"FEEDLINE" equivalent
WWW.NTMS.ORG
34.2
41.1
-6.9
Frequency
Dish diameter
Flyswatter Aperture
Height (reflect. Spacing)
24.192
0.3048
0.76
12.192
Suggested flyswatter =
0.5
GHz
meters
meters
meters
Note: 1 meter = 3.28 feet
meters - for this height and frequency
READ FINAL RESULTS HERE:
dBi
dBi
dB (effective gain of periscope over dish)
System Gain
Dish Gain
"FEEDLINE" equivalent
36.3
35.2
1.2
dBi
dBi
dB (effective gain of periscope over dish)
31
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Texas
Dish with Radome
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Finer Az Resolution
(and polarization sync)
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• AA5C had great article in recent QST on fine
azimuth control for 24 GHz
• My plan is to take a similar approach for both
flyswatter azimuth control and polarization
control
– Controlled via BASIC Stamp Microcontroller
– Will allow synchronization of polarization with
flyswatter azimuth
– Will calculate and display actual elevation as well
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10 more feet?
• The KA5BOU “Bowl”
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Questions?
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