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10 GHz Flyswatter Antenna Experiment

10 GHz Flyswatter Antenna Experiment

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10 GHz Flyswatter Antenna Experiment

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  1. 10 GHz Flyswatter Antenna Experiment Craig S. Young, KA5BOU ka5bou@arrl.net WWW.NTMS.ORG

  2. The Problem • 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 WWW.NTMS.ORG

  3. Potential Solutions • 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 WWW.NTMS.ORG

  4. Flyswatter? WWW.NTMS.ORG

  5. Actually, a Periscope • 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. WWW.NTMS.ORG

  6. Performance Analysis • Estimated performance at 10 GHz • Courtesy W1GHZ Excel Spreadsheet WWW.NTMS.ORG

  7. 1 ¼” Angle Iron ¾” Angle Iron 32” System Design – Top Reflector • Designed to mount to Rohn 55 Tower (17” leg center-to-center) • Includes rung hooks for easier installation • Clamps to tower legs WWW.NTMS.ORG

  8. Fly Swatter on the Ground WWW.NTMS.ORG

  9. 32” System Design- Dish Mount WWW.NTMS.ORG

  10. Dish Mount on the Ground WWW.NTMS.ORG

  11. Elevation Control • Used a TVRO actuator for control with a Winegard DM-4000 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 WWW.NTMS.ORG

  12. Flyswatter Controller WWW.NTMS.ORG

  13. Complete System WWW.NTMS.ORG

  14. “First Light” • NT5NT Beacon WWW.NTMS.ORG

  15. Recent Activity – Aug UHF Contest • Of course, there were only 2 10GHz entries from NTX • KA5BOU • NM5M • Both with same 10 GHz score! • Congrats, Eric! WWW.NTMS.ORG

  16. Recent Activity – Jan VHF Contest • 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 WWW.NTMS.ORG

  17. Azimuth Elevation Polarization Issues • In traditional dish installation for terrestrial work, elevation and polarization are fixed • More Degrees of Freedom! • Azimuth • Elevation • Polarization • Frequency WWW.NTMS.ORG

  18. Issues • Alignment – Base to Reflector • Pointing Resolution • Elevation • Polarization WWW.NTMS.ORG

  19. Alignment(base to reflector) • “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 WWW.NTMS.ORG

  20. Azimuth Pointing • 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 WWW.NTMS.ORG

  21. Azimuth Pointing WWW.NTMS.ORG

  22. Elevation Issues • 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 WWW.NTMS.ORG

  23. 50º 70º 45º 0º Elevation Issues (cont’d) • One degree of flyswatter tilt = 2 degrees of beam tilt! Beam=2(Elev) - 90 WWW.NTMS.ORG

  24. Elevation Issues (cont’d) • Higher flyswatter tilt = loss from spillover WWW.NTMS.ORG

  25. Polarization • Either dish or feed must rotate with flyswatter to maintain correct polarization WWW.NTMS.ORG

  26. Polarization • 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 WWW.NTMS.ORG

  27. Next Steps • Sun Noise Measurement? • Experiment with Other Bands • Permanent Dish Mount with Radome • Finer Resolution Az Control • Another 10ft? WWW.NTMS.ORG

  28. Sun Noise? • 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? WWW.NTMS.ORG

  29. 5760 Analysis 50’ run of LMR-600 would have approx 3.6dB loss WWW.NTMS.ORG

  30. 3456 Analysis 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 WWW.NTMS.ORG

  31. 24 GHz Analysis With 2 ft dish With 1 ft dish WWW.NTMS.ORG

  32. Dish with Radome WWW.NTMS.ORG

  33. Finer Az Resolution(and polarization sync) • 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 WWW.NTMS.ORG

  34. 10 more feet? • The KA5BOU “Bowl” WWW.NTMS.ORG

  35. Questions? WWW.NTMS.ORG