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How to Make a Base Loaded Antenna

A base-loaded antenna can improve signal strength, while saving space and reducing the cost of mounting a large vertical antenna. The base- or coil-load at the bottom of a vertical antenna balances the impedance, or resistance to electrical flow, that is inherent in a standing vertical antenna. The coil counteracts the antenna's impedance, and allows for a physically shorter antenna than would otherwise be required to tune to a particular frequency. Your radio transceiver transmits as if it were connected to a significantly longer antenna, due to the coil load.

Things You'll Need

Aluminum tube, 1/2-inch diameter, 78 3/4 inches long
Electrical wire, 14-gauge, 63 feet long
Coaxial cable with connectors, 50-ohm, 10 feet
PVC pipe, 5 1/2 inch outside diameter, 1 foot long
PVC cap, 5 1/2 inch diameter
PVC glue
3 machine screws with nuts and washers, 1/8-inch diameter, 1 inch long
Wire-stripping tool
Sand paper
Utility knife
Wire with alligator clips at both ends
Soldering iron and solder
Power drill and various bits
Electrical tape
Small piece of twine

Instructions

Preparation
- 1
  Cut the electrical wire into one 50-foot length, and two 6.5-foot lengths.
- 2
  Drill two 1/8-inch holes through the PVC tube, 1 inch from the end. Thread the electrical wire through the holes, leaving 1 foot of excess wire at this end of the PVC tube. Wrap the wire 34 times tightly around the tube, twisting the wire into a loop every 5 turns. Apply electrical tape to the wire frequently to keep the wire in place. The loops should stick out from the PVC tube.
- 3
  Drill two 1/8-inch holes in the PVC tube, after the 34th turn. Thread the wire through these holes, locking the wire in place. Sand the plastic insulation from the wire loops on the tube. Strip 1/2 inch of insulation from the 1 foot of excess wire left at the top of the tube.
- 4
  Drill an 1/8-inch hole, 1/4 inch from each end of the aluminum tube.
- 5
  Drill a 1/2-inch hole through the center of the PVC cap. Insert one end of the aluminum tube through the top of the cap. Insert a machine screw through the end of the aluminum tube, and fasten a nut and washer. The screw should keep the aluminum tube from slipping back through the cap.
Assembly
- 6
  Fasten the cap on the end of the PVC tube nearest the 1-foot length of wire.
- 7
  Drill a 1/8-inch hole through the aluminum tube just above the PVC cap, and fasten a machine screw loosely, using a nut and washer. Twist the PVC tube wire around the screw, and tighten the screw to the tube.
- 8
  Insert a machine screw through the hole in the free end of the aluminum tube, and fasten a nut and washer loosely. Tie a loop of twine around the screw, and tighten the screw to the tube. Hang the antenna from the twine.
- 9
  Cut a connector from one end of the coaxial cable. Remove 1 inch of insulation from this end. Pull the braided sheath back over the cable housing. Strip 1/4 inch of insulation from the plastic insulation, exposing the inner copper wire.
- 10
  Strip 1/2 inch of insulation from one end of each 6.5-inch length of wire. Solder the exposed wire ends to the coaxial braided sheath. Spread these ground radial wires out from the antenna.
- 11
  Attach the coaxial copper wire to a wire loop on the PVC tube using the alligator clips.
- 12
  Connect the free end of the coaxial cable to the external antenna jack on your radio. Tune the antenna by clipping different loops on the PVC tube.

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