The Barker & Williamson Model AS-20 is a short dipole for the 20, 15 and 10 meter amateur bands. Each band has a separate trap (10 and 15 meters) which will give maximum efficiency and still be a short antenna for small lots and limited space. On 15 meters the 10 meter traps work as loading coils, and on 20 meters both traps work as loading coils, keeping the antenna short for 20 meter operation. All short dipole antennas will have a bandwidth narrower than a full size half wave dipole. Therefore, an antenna tuner may be helpful.

The AS-20 is best installed as an inverted Vee. Satisfactory results may be obtained with the center as low as 20 feet, however 30 feet or more is recommended. If a flat top installation is desired, it is best to have the center supported due to the weight of the traps/loading coils and coaxial feed line.

INSTALLATION INSTRUCTIONS

(1) Please read through all the instructions before starting. It is imperative to follow the instructions step by step, in the order shown, to achieve satisfactory results with your antenna.

(2) Remember that throughout the assembly procedure, wire lengths are always to be symmetrical on both sides of the antenna. Your traps may or may not have a color dot on one end of them. You may ignore these color dots. They do not have to match each side.

(3) Cut the wire segments. The wires must be cut approximately 2 - 3 feet longer than the dimensions shown in figure 1. This is to leave room for the hookups and tuning adjustments. Here are the lengths that you should cut (including the 2 - 3 ft extra). Cut two wires 11', two wires 4', and two wires 3'. Remember, you can always trim the wire shorter after tuning, but once cut too short . . .

(4) Attach one end of the wire segments in the permanent manner shown in figure 2, working out from the center conductor. Allow roughly 6 to 8" of wire through the eyebolt before starting your wrap. Attach the 11' segments to both sides of the center connector. Attach the 3' segments to one side of the TR10 traps. Attach the 4' segments to one side of the TR15 traps.

(5) Now assemble the sections of the antenna together paying attention to figures 1 and 3. The wire segment lengths shown are your starting point for tuning the antenna. Make sure that you make temporary connections as shown in figure 3. This will leave each wire segment with one end permanently soldered, and the other end temporarily connected for adjustment.

(6) Raise your antenna, and check the VSWR on 10 meters. If the resonant frequency is low, shorten the 8' 5" segments. If it is high, lengthen the wires. After the desired frequency is achieved, make permanent attachment for these segments as shown in figure 2, trimming off excess wire.

(7) Next adjust the 13" segments for 15 meters in the same manner.

(8) Finally, adjust the 21" segments at the insulators for 20 meters.

SWR curves: