Building the antenna - Constructing the elements

Now it's time to start building. You will start out by making an "S" curve from the long wire.



Side feed



Measure back from each end of the wire one quarter wavelength (as calculated above) and bend each end in opposite directions 90 degrees. You now have an elongated "S" with tips equal to your calculated quarter wavelength.



Next, we complete the "S". Measure back from each bend TWICE your quarter wavelength and bend 90 degrees in the same direction as your previous bend on that end. Do this to both ends to form an "S"

Now we need to bend the radius in our "S". I did this by taking my pliers and making small bends all the way around the 1/2 wavelength side until the end met with the middle of the antenna. The tip of the wire should meet the center at a ~105 degree angle. It will not (and should not) intersect at 90 degrees.



The wire should look like a figure “8”.



With the other wire you make a 110 degree arc. Measure back ¼ wavelength from each end of the wire and bend them inward to form a “U” shape. Once done, put an arc on the backside to form the element.



Now you need to twist your figure “8” wire. The direction will determine the antenna polarization. The polarization is determined by curling your fingers from the center of the element around the radius and pointing toward the tip. Which hand did you use? That is the polarization. The unit in the pictures is RHCP.



Take your figure "8" and twist one side 90 degrees along the central axis of the element. One radius should be flat and the other should be upright.



Once done, you need to bend a 120 degree radius in the center of the bent “8”. Set the antenna so the lobes are at 45 degrees to the ground and bend the center 60 degrees in one direction (It doesn’t matter which way) to form a 120 degree bend.



Base feed



For this you simply make 3 of the short elements. For this, jigs are easy to make or you can just bend by hand.



Easy to make Jigs



I have seen the most impressive jigs to make these antennas from Chad Kapper's on Flite Test to some vendors even selling commercial units. It isn't necessary... I have used a simple cheap wooden dowel for over a year now and it works really well. You simply drill a hole 1/4 wavelength deep into the center of the dowel and then cut a flat spot around the side 1/2 wavelength away.



To use: Insert the wire into the dowel and wrap around to the flat spot. It's that easy!



-Alex

KJ4RIV