Circularly polarised radiation from singly fed equilateral-triangular microstrip antenna

The paper presents an equilateraltriangular microstrip antenna (MSA) that can produce circularly polarised waves with a single feed. Theoretically predicted results, such as the operating frequency and feed location with which good circularly polarised radiation can be obtained, are compared with experimentally obtained results. The calculations for the axial ratio and the radiation pattern are also compared with the measurements. For all of the results the agreement is found to be quite good, and it is confirmed that a singly fed equilateral-triangular MSA can produce two kinds of good circularly polarised waves at two different frequencies.