Recent postings to List your favorite SOTA antenna on QRZ.com referred to an experiment Comparing the performance of an inverted vee dipole with a small transmitting loop on 20m as propaganda.
The experiment above states The manufacturer of the loop gives a calculated efficiency of 39.754% at 14174 kHz.
This is very similar to that claimed by Chameleon of their P-Loop2, so it will be used as a study example.
Experimental method
Taking the Chameleon P-Loop2 on 20m as the study example,
- build a model in the AA5TB spreadsheet;
- build an NEC-4.2 model in free space and reconcile it with AA5TB;
- build an NEC-4.2 model in proximity of ground compare it with AA5TB;
- build an NEC-4.2 model in proximity of ground and add realistic estimates for conductor and capacitor loss and compare it with AA5TB;
- compare the NEC-4.2 model in proximity of ground with realistic losses to Chameleons published VSWR curve.
Chameleon gives the following table on their website.
Step1: build AA5TB model
An extract from the AA5TB model using Chameleon’s stated dimensions. The efficiency figure reconciles exactly. Continue reading STL propaganda indeed