Printed loop array antenna radiating a circularly polarised wave

Nakano et al. (1989, 1993) revealed that a loop antenna printed on a dielectric substrate and fed from a coaxial line can radiate a circularly polarised wave (CPW) when perturbation segments are used. The printed loop antenna possesses an advantage over a circular patch antenna in that it has a smaller circumference. Its smaller size makes it suitable for use as an array element. The purpose of the present paper is to realise a high gain, low-profile (flat) CPW array antenna using printed loop elements. The loop elements are designed for a frequency of 11.85 GHz, and arrayed on a thin circular cavity (Nakano et al. 1992, 1993). CPW beam formation is discussed and experimental results are presented