Amateur Radio Archive

The DoubleDiamond Quad

By Al Christman, KB8I Grove City College 100 Campus Drive Grove City, PA 16127-2104

introduction

After getting married in 1991,1 moved into the small house which my wife had already been renting. In the center of the back yard I put up a 65-foot mast composed of several "recycled" sections of TV tower, with a length of steel pipe on top for good measure. A variety of single and multiband inverted Vs were hung from the top of this mast, with good success, but I had been searching for a high-performance wire antenna which could be used for working DX on 20 meters. This article describes the

Inverted Vee Freq = 14.225 MHz

Elevation Plot Azimuth Angle = 0.0*

Elevation Plot Azimuth Angle = 0.0*

Fig 1—Broadside radiation pattern for a 20-meter inverted V with apex at 65 feet. (Beamwidth=16°, Take-off angle=16°)

Stacked inverted Vees Freq = 14.225 MHz

Elevation Plot Azimuth Angle =0.0*

Elevation Plot Azimuth Angle =0.0*

Fig 2—Broadside radiation pattern for stacked 20-meter inverted Vs in phase. (Beamwidth=21 Take-off angie=19°-)

results of some computer-modeling studies which I have performed using ELNEC

Background

The inverted V is one of the most widely used antennas in Amateur Radio today. It is simple, easy to build, and easy to get working. It provides a fair amount of gain (compared to an isotropic source) and can be adjusted for a near-perfect impedance match to 50-ohm coaxial cable. Fig 1 is a plot of the broadside radiation pattern for a 20-meter inverted V, when mounted on my mast at an apex height of about 65 feet. The legs slope downward at a 45° angle, and their length has been adjusted to produce an input impedance which is almost purely resistive. Notice that there is a good low-angle bidirectional lobe at a take-off angle of 16°, with a maximum gain of about 6.5 dBi, Unfortunately, there is also a lot of

ELNEC is available from Roy Lewallen, W7EL, PO Box 6658, Beaverton, OR 97007.

Fig 3—Physical configuration of the double-diamond quad antenna.

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