HOW TO BUILD YOUR OWN REAR MOUNTED ROTATABLE POLARITY ANTENNA IN 2 MINUTES
(July 13th, 2015)
This 2-minute video clip shows how to build a "KK6FAH Rear Mounted Rotatable Polarity Antenna" very simply. Really, there is nothing complicated here and to me, that is the beauty of this whole system which can be built without any compromise with very simple means.
The first step for the antenna builder is to choose a computer optimized antenna design. Many of them are available on the web. YU7EF and G0KSC made available outstanding designs which I have tried successfully and highly recommend.
Once you have selected an antenna design, I strongly recommend to model it in EZNEC and make proper corrections if you make any modifications to it. For instance, in my case, I use elements of 4.76 mm diamater towards the rear end of the antenna and smaller elements of 3.17 mm diameter for the elements towards the front end of the antenna in order to minimize the weight and potential sagging. These types of changes require careful modeling and adjustments in the element lengths.
Once that is done, the rest of the construction is straight forward as shown in the video. Remember that the choice of the BALUN is absolutely critical. I strongly recommend the I0QM type.
Below a list of key suppliers for the critical parts involved in this design:
Let me know how your construction goes and Good Luck!
***WARNING: For Best Resolution for the videos below, it is critical to select 720p HD resolution in the youtube "settings" at bottom right of the player. The 360p default setting won't yield good enough resolution to see the details. It will take several seconds before the High Resolution kicks in, so you will need to restart the video from the beginning when the High Resolution is active and select to view the video in "Full Screen Mode" for best experience...***