Small magnetic loop antenna
The magnetic loop antenna consists of two circles: one large one and a smaller one in the larger one. The circumference should be between 0.1 and 0.25 wavelength for optimal efficiency.
Formulas
 Schematic
Schematic



 l is the symbol for length and is measured in meter (m). 
f is the frequency in  megahertz  (MHz). 
d min  is the symbol for minimum diameter and is measured in meter (m). 
d max  is the symbol for maximum diameter and is measured in meter (m). 
l min  is the symbol for minimum conductor length and is measured in meter (m). 
l max  is the symbol for maxinum conductor length and is measured in meter (m).