stealth antennas

Stealth Antennas

David Treharne

N8HKU

March 10, 2005

Introduction

• Most Hams

want a large antenna

• Most don’t get one.

5-band-10/12/15/17/20 Meters, 11 Elements.

Price: $1159.95

Why Not?

• Cost: Antennas and towers are quite expensive.

• Zoning: Restrictive covenants make it difficult and expensive to put up a large antenna array

• Space: Many homes/condos/apartments do not have the space

• Spouse: Beauty is in the eye of the beholder

Solution: Stealth Antennas

• It turns out that an antenna does not have to be BIG to work

• It does not have to be outside to work

• It does not have to be high powered to work

• It does not have to be permanent to work

What is Needed

• An attic, a porch, a deck, a flagpole, or even a ceiling

• A tuner

• A good set of speakers or headphones

• Patience

• An occasional contest

The N8HKU Condo

• No outside antennas

• Antennas covering 10m-80m, 144, 440 MHz

The Condo Antenna Farm

• SPI-RO trap dipole for 10-20M

• Isotron combo antennas for 40M and 80M

• Cushcraft Ringo Ranger 2m/70cm Vertical

Getting the Antennas in the Space

Trap dipole across the attic, bent to “see” Europe

Need to trim them to resonance

Metal can interfere with them

Resonance of Dipole

after Trimming

No tuner needed for 20m. Other bands can be tuned, including WARC bands of 12M and 17M.

Other Antennas

• Isotron antennas needed significant trimming, and still need tuning.

• Ringo Ranger had horrible transmission to the Tin Lizzy until I moved it 1 ft over, now great reception

Power

• May not be a good idea to run full power– Interference potential with home electronics

• Issue with home stereo

– RF Exposure needs to be analyzed for both yourself and for others in the house or in the adjoining units

• I performed a full analysis

– RF can get into your equipment• Keyboard acts up on 10m

• Needed to add an isolation choke between my radio and computer to keep RF out of the speaker system

Where have I worked?

• United States– 40M/80M is within 1,000

miles only due to near vertical sky bounce

– Oregon/Washington tough

• ROW:– Russia, South America,

U.K, Germany, Israel, Australia, Finland, Italy, Croatia, Spain, Netherlands, Japan

• All of that on SSB– Contests help: late in

contest, all the Big Guns have been worked, and the operators listen better for the weaker signals

• Many countries worked on RTTY or PSK 31 as well.– Can use less power

– Signals are stronger

– Less atmospheric interference

Resources

• ARRLWeb: Putting Up Your First Antenna Simple antennas for HF and VHF -- and simple instructions for putting them up!http://www.arrl.org/tis/info/antbegin.html 2002-02-05, 8498 bytes

• ARRLWeb: Limited Space and Indoor Antennas

– techniques for building and using limited-space and indoor antennas.http://www.arrl.org/tis/info/limited.html

• The Care and Feeding of a Condo Antenna Farm

– The Care and Feeding of a Condo Antenna Farm 64 April 2001 In By Al Alvareztorres, AA1DO

• ARRLWeb: Antenna - Indoor

– techniques for building and using limited-space and indoor antennas.http://www.arrl.org/tis/info/antind.html