Friday, December 30, 2011

Quick Antenna: Wire Ground Plane

The quick and easy first antenna is a wire ground plane.  This antenna is probably the most affordable and rugged antenna you could have.  It will serve as a base station antenna and will also come in hand for portable use when you get another for your base station. 

You will need a SO-239 connector 8 ½ feet of #12 or 14 wire and four ½ inch by 6-32 bolts with 8 washers and 4 nuts to fix.

Cut 5 pieces to 20 ½ inches long.

Solder one piece of wire to the center conductor where it sticks out of the insulation on the bottom of the connector.   

Bend a loop in one end of each of the remaining wires to fit on the bolts. Put a bolt from the bottom up into one hole on the connector and slide on one washer. Slide on one of the wire followed by another washer then put a nut on top and tighten. Repeat for the other 3 holes.

Once the wire are attached as shown, bend the 4 wires downward about 45 degrees.

Now you’re ready to build the mast.  This will be a piece of ¾ PVC of any convenient length.  Mine is about 5 feet long.

About 6 inches from one end of the PVC, cut an oval shaped hole just large enough to slip the coax connector on the end of your coax cable into the PVC.  Slide the cable up and out the closest end and connect antenna.

Slide the cable up and out the closest end and connect antenna.

Slide the coax back down until the antenna sit down onto the end of the PVC.  You are ready to tune the antenna.  Note that winding the coax around the mast helps hold the antenna in place.

The antenna in the pictures has served me for many years now.  It has fall over while on a 30 foot mast.  The mast was damaged by the antenna was not.  It spends much of its life behind the seat in my truck where it gets bent and banged.  I did originally solder the 4 radial wires on the connector but that proved to be a weak point.  The radials keep breaking off so I went to bolts and have not had one break since.  Maybe it was just bad soldering but bolts work for me.

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