Super/Ewe Terminated Broadband Loop Antenna

SuperLoop/psuedo-Ewe Switchable Configuration

Plots for 1 kΩ terminated SuperLoop (left) and 2.6 kΩ terminated psuedo-Ewe (right) at 1000 kHz.

     An inline switch inserted at the midpoint of the bottom horizontal wire of a variable termination SuperLoop antenna allows for operation as a pseudo-Ewe antenna (see above schematic). While the SuperLoop performance typically provides a deep although narrow backside null, the psuedo-Ewe reduces overall high angle skywave. Note that because the SuperLoop is not referenced directly to ground, this switchable configuration scheme is far less than optimal for a spec Ewe which requires a good ground reference to perform well. Therefore the poorly grounded pseudo-Ewe in this configuration does not provide a deep backside null. However, in lab tests this pseudo-Ewe does help to reduce high angle skywave interference. Installing the switch is an easy modification to a SuperLoop antenna. It's a quick and dirty method of providing an alternative antenna for the SuperLoop user.

Super/Ewe Ground Alternative

Plots for 1 kΩ terminated SuperLoop and 640 Ω terminated Ewe (grounded SuperLoop) at 1000 kHz.

     An alternative design places a switch between the midpoint of the SuperLoop bottom horizontal and earth ground. Closing the switch connects the SuperLoop to ground, essentially converting it into something more closely resembling a spec Ewe antenna. The backside nulling of this Ewe configuration is improved over the non-grounded version, but models indicate that high angle rejection is not as good; the Ewe pattern now looks more like a SuperLoop.

Antenna Dimensions

     Typical Ewe antenna dimensions are x = 40-ft (horizontal), z = 10-ft (vertical), which is about as small as it gets for a SuperLoop antenna. Any smaller would require amplification. Typical SuperLoop dimensions are comparable to the Ewe at x = 50-ft, z = 15-ft. However, antenna dimensions are very forgiving. EZNEC model SuperLoop performance for various dimensions is graphed below.

©2017 Bruce A. Conti  ¡BAMLog!