Antennas for the Antennas for the OfficeOffice

Presented toPresented to

Challenges of Office Challenges of Office RadiosRadios

RF Everywhere!RF Everywhere! High computer densityHigh computer density ““Leaded” glassLeaded” glass Rat mazesRat mazes Tons of power circuitsTons of power circuits

Types of Antennas Types of Antennas EvaluatedEvaluated

AntennasAntennas Rubber Duckie (Stock HT model)Rubber Duckie (Stock HT model) Dual Band ¼ Wave Mag MountDual Band ¼ Wave Mag Mount Dual Band Roll-up Portable J-PoleDual Band Roll-up Portable J-Pole 70cm Roll-up Portable J-Pole70cm Roll-up Portable J-Pole PVC – Encased J-Pole Base StationPVC – Encased J-Pole Base StationRadio:Radio: Alinco DJ-580Alinco DJ-580

Pros/Cons of Rubber Pros/Cons of Rubber DuckiesDuckies

Pros:Pros: SmallSmall LightweightLightweight FlexibleFlexible InexpensiveInexpensive Don’t require Don’t require

ground planeground plane

Cons:Cons: Poor reception and Poor reception and

transmitting transmitting efficiencyefficiency

Size and Size and effectiveness are effectiveness are usually inversely usually inversely proportionalproportional

Pros/Cons of Mag Pros/Cons of Mag MountsMounts

Pros:Pros: Temporary Temporary

MountingMounting Easy to Easy to

install/removeinstall/remove InexpensiveInexpensive

Cons:Cons: Require metal Require metal

mounting surface mounting surface to provide ground to provide ground planeplane

Bulky compared to Bulky compared to DuckiesDuckies

Pros/Cons of J-PolesPros/Cons of J-Poles

Pros:Pros: LightweightLightweight InexpensiveInexpensive Don’t require Don’t require

ground planeground plane Easily home-Easily home-

brewedbrewed Good base-station Good base-station

solutionsolution

Cons:Cons: Can be difficult to Can be difficult to

tunetune Bulky compared to Bulky compared to

¼ wave mag ¼ wave mag mount and Duckiemount and Duckie

Measuring Antenna Measuring Antenna EffectivenessEffectiveness

Standing Wave Ratio (SWR)Standing Wave Ratio (SWR) Ratio of transmitted power to reflected Ratio of transmitted power to reflected

powerpower 1:1 is the holy grail and a supreme time-1:1 is the holy grail and a supreme time-

wasterwaster S-Meter (empirical)S-Meter (empirical) GainGain

Increase in effective power radiated or Increase in effective power radiated or received by an antennareceived 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 2mSWR on 2m

0

1

2

3

4

5

6

7

144 144.5 145 145.5 146 146.5 147 147.5 148

Dual Band Roll-Up440 Roll-UpPVC Dual BandMag Mount Dual BandRubber Duckie

SWR on 70cmSWR on 70cm

0

1

2

3

4

5

6

7

440 441.3442.5443.8 445 446.3447.5448.8 450

Dual Band Roll-Up440 Roll-UpPVC Dual BandMag Mount Dual BandRubber Duckie

S-Meter Values S-Meter Values Transmitting 2mTransmitting 2m

00.5

11.52

2.53

3.54

Dual BandRoll-Up

440 Roll-Up

PVC DualBand

MagMount

Dual Band

RubberDuckie

High Power Medium Power Low Power

S-Meter Values S-Meter Values Transmitting 70cmTransmitting 70cm

0

0.5

1

1.5

2

2.5

3

Dual BandRoll-Up

440 Roll-Up

PVC DualBand

MagMount

Dual Band

RubberDuckie

High Power Medium Power Low Power

S-Meter Values S-Meter Values Receiving 2mReceiving 2m

0123456789

Dual BandRoll-Up

440 Roll-Up

PVC DualBand

MagMount

Dual Band

RubberDuckie

High Power Medium Power Low Power

S-Meter Values S-Meter Values Receiving 70cmReceiving 70cm

0123456789

Dual BandRoll-Up

440 Roll-Up

PVC DualBand

MagMount

Dual Band

RubberDuckie

High Power Medium Power Low Power

J-Pole Antenna TheoryJ-Pole Antenna Theory

Vertically PolarizedVertically Polarized 2 elements: radiator (3/4 2 elements: radiator (3/4

wavelength)and matching stub (1/4 wavelength)and matching stub (1/4 wavelength)wavelength)

Essentially an end-fed half-wave Essentially an end-fed half-wave antennaantenna

A Simple Dual Band J-A Simple Dual Band J-PolePole

Antenna Resources and Antenna Resources and ReferencesReferences

Why an Antenna RadiatesWhy an Antenna Radiateshttp://www.arrl.org/tis/http://www.arrl.org/tis/

info.whyantradiates.htmlinfo.whyantradiates.html Decibel (dB)Decibel (dB)

http://http://ewhdbks.mugu.navy.mil/decibel.htmewhdbks.mugu.navy.mil/decibel.htm ““An Easy Dual Band VHF/UHF An Easy Dual Band VHF/UHF

Antenna”Antenna”by Jim Reynante, KD6GLF. Published in by Jim Reynante, KD6GLF. Published in

QST Sep 1994, p. 61.QST Sep 1994, p. 61.