75 m Loop Antenna at W4UOA

Corrected version -- original had results for double the intended loop length.
Here is some analysis of a loop antenna proposed by W4UOA. The following slide show presents impedance vs frequency for several bands. Resistance and reactance are plotted in the upper half of each slide, and impedance magnitude and phase are in the lower half. Click on any slide to view it in the source album. Additional magnification is available using the magnifier icon in the Picasa album view.



The radiation patterns below show the typical progression in frequency, with more lobes and lower angle of radiation as frequency increases. There is a large amplitude difference between the peaks and nulls in the patterns at higher frequencies.



The antenna elements and support wires are the silver lines. The feedline is blue. The color-coded radiation pattern was left at original scale to show its relationship to the antenna structure. The program allows zooming the pattern much larger, such that the antenna structure is engulfed. Viewing at any azimuth and elevation angle, in increments of 5º, is available. Standard 2-D plots are also available.

The predicted performance of this antenna seems consistent with other published analyses of loop antennas, and does not appear to be adversely affected by un-grounded metallic support wires.