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An Improved Version
(See older version here)

3 element = 7 dBd Gain
5 element = 9.4 dBd Gain
10 element = 13 dBd gain

These Collinear antennas are " 4 " Megs wide and  "must be supported"  at the top by a yard arm or tree limb.

2 meter collinear antenna plans

Building instructions for the NEW WB3AYW Collinear Antenna

This is for Two Meters only 02/11/2014
the other bands are similar.

NEVER PUT AN ANTENNA UP NEAR POWER LINES !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

NO MATTER HOW CAREFUL YOU ARE !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!


Coil example (see details below)

Get water pipe, (CPVC) for hot/cold water at your building supply store, it is tannish / white and 5/8 inch outside diameter.
Cut to 6 inches long for all coils assemblies. See photo above. Measure in on each end 2 1/4 inches and mark.

Measure the spacing between these marks and make sure they are 1 1/2 inches apart.
Drill a 1/8 inch hole through each mark all the way through the CPVC pipe.

Measure out 3/8 inches from each hole and drill the same as the first set of holes. These are not as critical as for measurement as the first set of holes you drilled.
There will be a modification later to these holes.

Cut your #14 SOLID insulated, TNN wire 14 inches long, one for each coil. Bare wire 1 1/2 inches then bend first end slightly after inserting it through the first inside hole, then bend over more. Only 3 turns in between wire ends on coil. Wire ends will come out on the same side of the coil form.

There should be 8 = inches of wire plus the two end wires through the tubing.
Wind 8 1/2 inches of #14 solid wire on coil form tightly and stop. If using the correct tubing (as I use), the number of turns are 3 1/2 with insulation.

Pull coil wire towards the other end of the CPVC form.
Feed the second end through the inside hole on the other end and PULL TIGHT with Pliers!
Bend over like you did on the 1st end; this keeps the coils the correct length.

If you do not pull the coil wire tight it will vary the length and vary the frequency / phasing, with up tilt. If wires are too long or too short = down tilt, or if holes too wide = Down tilt, less capacitance, higher frequency.

Trim the wire ends, to the length of the outside holes.
Make up all of your coil assembly's, 2, 4, 9 or whatever you want. It takes 4 coil assemblies for a 5 element design.

On the outer holes of the CPVC assemblies; re-drill the hole at a slope next to the wire ends so your radiating wire will slide through from the inside out. See photo above.
Top radiator
Bare 3 inches and make a 1/2 inch loop with your #12 stranded wire and solder the loop good, this will have all of the weight of the antenna on it.

Measure and cut top element to 37 1/2 inches length, this element is the only one, with END EFFECT on it.

Bare about 3/8 inchs of the top element wire and feed through the center (inside) of the CPVC and out through the modified hole, and solder securely to the coil wire.

Cut all other (#12) wire elements to 38 1/2 inches long.
Bare the #12 stranded wires (3/8 inch) on both ends.

Feed through the center of the CPVC and out through the modified hole that you re-drilled, making sure that it goes to the inner hole and solder to the coil wire while making sure the radiator wire goes to the inner hole before soldering! Thus keeping the length of the radiators correct.

Solder all connections as you go.
Do the same to all other elements.

Cut a piece of CPVC 26 inches long.
Slide the 26 inch piece of CPVC over the lower element.

The matching section is made from 300 OHM Ladder Line. I use the Wireman's Ladder Line.
Cut Ladder Line to 18 1/2 inches then bare and bend the bottom to short it. Solder the ends shorting it.

Measure up, 3 1/4 inches from the short and bare the 2 wires of the Ladder Line about 1/2 inch.
This is the 50 OHM feed point APROXIMATELY.
Use 3 or 4 feet of RG8X for a pigtail section. It will fit inside of the CPVC tubing with the ladder line soldered to it. Seal all connections after tune up to prevent moisture and Bees! Yes I said BEES!

Prepare your RG8X coax and solder to ladder line feed point at the 3 1/4 inch point you bared.

The length of the Ladder Line needs trimming to a length 16 7/8 inches.
Slide 26 inch piece of CPVC up over the lower element.

Solder the bottom radiator to the side with the coax CENTER attached on the matching section.
RECHECK!  Make sure the side of the ladder line connection to the element is correct.

Put antenna up horizontally about 4 feet above ground and check VSWR, you should be lower in frequency than you want to be. Or the ladder line is too short!

If the frequency is low, then slide the 26 inch piece of CPVC up or down over the matching network or lower element and trim opposite side (short side) of the 300 ohm ladder line.
Cut 1/8 inch at the time, to bring it up to frequency while putting the ladder line sleeve back on each time you check VSWR. The sleeve will change the frequency about 2 Megs, Be careful as you cut only 1/8 th of an inch at a time. Then recheck SWR.

When tuned, the short side should now be about 16 3/4 inches long.
Seal all open wire connections from moisture and Bees.
Seal up top and bottom of all elements sleeves. The bottom sleeve needs to be weather tight at the top to keep moisture out of the matching section and your coax.

Bees like to build nests, so seal on both ends of all other coil assemblies.
Leave the 1/8 inch holes open at the top and bottom, on the side of the coils for water drainage.
The gain of the 5 element is about 9.7 dBd's (not dBi's) per my antenna program.

For any problems or questions call me, 8AM till 4PM EST. 770 893 1216.
My thanks to KK1CW for the original spreadsheet; without him this program would not be possible!
Also see KK1CW for more antenna programs.

Leonard Shick WB3AYW




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