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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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Antennas for the office presented to

Antennas for the OfficePresented to


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)


Swr on 2m

SWR on 2m


Swr on 70cm

SWR on 70cm


S meter values transmitting 2m

S-Meter Values Transmitting 2m


S meter values transmitting 70cm

S-Meter Values Transmitting 70cm


S meter values receiving 2m

S-Meter Values Receiving 2m


S meter values receiving 70cm

S-Meter Values Receiving 70cm


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


A simple dual band j pole

A Simple Dual Band J-Pole


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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