New insights on loop radiation efficiency

Circuit loop area reduction is a frequently used EMC technique for minimizing differential mode current radiations and improving the overall immunity of products from electrical noise. The efficiency characteristics of loop radiation are studied and new facts on loop radiation are described. The relationship of the radiation amplitude efficiency and frequency of the first radiation-peak with the size and shape of the loop area is explained. A mathematical model is presented for calculating radiations first peak and its frequency from the loop area. The effect of loop area shape on peak radiation frequency is experimentally verified. Experimental data is also provided to demonstrate that the radiation amplitude efficiency peak shifts to higher frequencies when the loop area is minimized.