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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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Presentation Transcript
challenges of office radios
Challenges of Office Radios
  • RF Everywhere!
  • High computer density
  • “Leaded” glass
  • Rat mazes
  • Tons of power circuits
types of antennas evaluated
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
pros cons of rubber duckies
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
pros cons of mag mounts
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
pros cons of j poles
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
measuring antenna effectiveness
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)
j pole antenna theory
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
antenna resources and references
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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