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The Hula Loop, designed by Glenn, AC7ZN and Chris, KA7ADN is an inexpensive magnetic loop antenna you can build.
The Hula Loop, designed by Glenn, AC7ZN and Chris, KA7ADN is an inexpensive magnetic loop antenna you can build.
This is an indoor/attic antenna that tunes all bands from 7 MHz (40m) to 30 MHz (10m). It can handle up to 100 watts. Like all magnetic loop transmit/receive antennas, the antenna must be tuned to the desired operating frequency. On this antenna, this is done by lifting a capacitor plate (flap) with a small stepper motor. Two toy hula hoops with aluminum roof flashing form both the antenna loop (inductor) and the tuning capacitor. Because there are no joints with potential loss in the antenna, we believe this antenna is one of the more efficient loop antennas currently available.
Parts and Construction Tips
We found suitable hula hoops hanging on the bike racks at WalMart. We used the irridescent foil covered hoops and removed the foil. Don't remove the label as that helps hold the hoop together.
We like the Duck brand High Performance packing tape found in the mailing section of WalMart office supplies.
We like the Duck brand High Performance packing tape found in the mailing section of WalMart office supplies.
The stepper motor and manual motor controller board are available from Aliexpress.com for lower cost. We have had good success with Aliexpress. Search on "80mm stepper motor" and "stepper motor controller board". The motor says it is 9V but is usable at 12V without problems as long as the duty cycle is not too long.
AC7ZN
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