The Astroplane (AV-101) antenna.

Background.
The Astroplane antenna is a product of 1960s America. Citizen's Band radio was a 23 channel, AM only system and required a license to operate.
FCC restrictions limited the antenna height to 20 feet above the property, and most CB antennas would have been basic 1/2 or 5/8 wave monopole and base loaded types.
The Astroplane was designed to offer an improved radiation pattern, giving greater distance, while still allowing the antenna to be mounted on the roof without exceeding the height limit.

Quick Reference.
Creators: Manufacturer:	Louis J. Martino, Herbert R Blaese. Avanti Communications
Specifications.
Claimed gain: Impedance: SWR: Bandwidth:	4dBi. 50 Ohms. Pretuned, below 1.4:1 27 - 29.7MHz.
Measurements. Please note that component measurements are complete lengths. Once parts are slotted together, the electrical length may be different.
Full length: Top section length: Top Radials: Bottom half length: Loop Diameter: Fiberglass rod length: Mounting pole length:	12 Feet. 4 Feet. 4 of @ 24 Inches 8 Feet. 30.5 Inches. 13 Inches. > 12 Feet.

Design.
The antenna is designed to radiate maximum signal from the top section, sending the signal over roof tops to avoid the loss of signal through buildings.
Although the design is intended to have a 1/4 wave top section, this would make the antenna a total of 16 feet. As the antenna should have at least 8 feet of mast below it, the total when mounted would be more than the 20 feet maximum.
The answer was to use a shorter top section of around 1/8 wave length, and top load it to the 1/4 wavelength with a capacity hat (the top radials). This combination lowers the radiation angle, but also decreases the bandwidth.
For wider bandwidth use, this top section can be changed for a straight 1/4 wavelength section.

Although the original Astroplane may no longer be available, there may be copies of it being made by other manufacturers. At the present time, such copies do not appear to be available within the UK.


Parts list.

QTY. 4 2 2 2 2 1 1 1 --- 1 2 4 6 1 2 12 4 1 6 1 1 1 4 1 2 2 2 1

PART. 1789 1050 2554 2737 9002 SUB-102 SUB-101 1313 SUB-103 1098 1092 1099 1090 1152 1156 1153 1196 1188 1186 1187 1071 1010 1303 1056 1057 2556 1304 2786

DESC. 1/8 x 24" Steel Radials. 3/8 x 24" Curved Tube. 3/8 x 24" Curved Tube. 3/8 x 48" Straight Tube. 3/8 x 48" Straight Tube. 5/8 x 48" Straight Tube. Base Clamp with SO-239 3/8 x 13" Fiberglass rod. Hardware Kit. 1/4-20 Square nut. 5/16" Hex nut. 10-32 Square nut. 1/4-20 Hex nut 1/4" Flat washer. 5/16 Star washer 1/4 Star washer 10-32 x 3/4" Screw. 1/4-20 x 1" Screw. 1/4-20 x 3/4" Screw. 1/4-20 x 1.25" Screw. 5/16 x 1.75" U-Bolt. Plastic plug for 1/2" tubing. Plastic tip for SS Radial. Mast Clamp. Spreader Clamp. Loop Clamp Retainer Clip. Instruction Manual.

Bottom loop.



Clamp.
CAUTION:
Hold metal sleeve inside black plastic insulator while inserting Tube C. If this is not done and sleeve is moved, a broken connection between coax connector and antenna may develop.

OTHER NOTES:
Tube C connects to inner conductor of coax, and a plastic plug fits into the top of Tube C top stop rain from entering the tube. Tube A, clamp metal body.
When tested on a meter, all parts of the antenna should read short circuit to the coax outer shield. The SO239 will also read as if the antenna is short circuit.