Antennas for the Office Presented to

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

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

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

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

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

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

SWR on 2m

SWR on 70cm

S-Meter Values Transmitting 2m

S-Meter Values Transmitting 70cm

S-Meter Values Receiving 2m

S-Meter Values Receiving 70cm

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

A Simple Dual Band J-Pole

Antenna Resources and References Why an Antenna Radiates Why an Antenna Radiateshttp:// Decibel (dB) Decibel (dB) “An Easy Dual Band VHF/UHF Antenna” “An Easy Dual Band VHF/UHF Antenna” by Jim Reynante, KD6GLF. Published in QST Sep 1994, p. 61.