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Antennas for the Office Presented to

Antennas for the Office Presented to. Challenges of Office Radios. RF Everywhere! High computer density “Leaded” glass Rat mazes Tons of power circuits. Types of Antennas Evaluated. Antennas Rubber Duckie (Stock HT model) Dual Band ¼ Wave Mag Mount Dual Band Roll-up Portable J-Pole

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Antennas for the Office Presented to

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  1. Antennas for the OfficePresented to

  2. Challenges of Office Radios • RF Everywhere! • High computer density • “Leaded” glass • Rat mazes • Tons of power circuits

  3. Types of Antennas Evaluated Antennas • Rubber Duckie (Stock HT model) • Dual Band ¼ Wave Mag Mount • Dual Band Roll-up Portable J-Pole • 70cm Roll-up Portable J-Pole • PVC – Encased J-Pole Base Station Radio: • Alinco DJ-580

  4. Pros: Small Lightweight Flexible Inexpensive Don’t require ground plane Cons: Poor reception and transmitting efficiency Size and effectiveness are usually inversely proportional Pros/Cons of Rubber Duckies

  5. Pros: Temporary Mounting Easy to install/remove Inexpensive Cons: Require metal mounting surface to provide ground plane Bulky compared to Duckies Pros/Cons of Mag Mounts

  6. Pros: Lightweight Inexpensive Don’t require ground plane Easily home-brewed Good base-station solution Cons: Can be difficult to tune Bulky compared to ¼ wave mag mount and Duckie Pros/Cons of J-Poles

  7. Measuring Antenna Effectiveness • Standing Wave Ratio (SWR) • Ratio of transmitted power to reflected power • 1:1 is the holy grail and a supreme time-waster • S-Meter (empirical) • Gain • Increase in effective power radiated or received by an antenna • Measured in DeciBels (dB) • Gain (in dB) = 10 log(P2/P1)

  8. SWR on 2m

  9. SWR on 70cm

  10. S-Meter Values Transmitting 2m

  11. S-Meter Values Transmitting 70cm

  12. S-Meter Values Receiving 2m

  13. S-Meter Values Receiving 70cm

  14. J-Pole Antenna Theory • Vertically Polarized • 2 elements: radiator (3/4 wavelength)and matching stub (1/4 wavelength) • Essentially an end-fed half-wave antenna

  15. A Simple Dual Band J-Pole

  16. Antenna Resources and References • Why an Antenna Radiates http://www.arrl.org/tis/info.whyantradiates.html • Decibel (dB) http://ewhdbks.mugu.navy.mil/decibel.htm • “An Easy Dual Band VHF/UHF Antenna” by Jim Reynante, KD6GLF. Published in QST Sep 1994, p. 61.

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