[1] A new series-fed circularly polarized antenna (SFCPA) in microstrip configuration, which consists of a traveling-wave-type crank-line antenna (CLA) and a resonant-type square-ring slot antenna (SRSA), is developed. Unlike the conventional crank-line (CL) antenna array with an open end or a resistive load, the proposed SFCPA uses the SRSA at the termination of the CLA and thus exhibits not only a broad circularly polarized (CP) bandwidth but also a large antenna gain. The characteristics of the SFCPA, including the leaky-wave radiation and the circular polarization, are examined in terms of the dispersion diagram and the current distribution. The SFCPA with the two-cell CLA and the terminated SRSA is fabricated and measured to demonstrate the 10-dB return loss and 3-dB axial ratio (AR) bandwidths of 34.3% and 30.5%, respectively. The frequency-scanning radiation patterns with a 5-7 dBi antenna gain are also presented in the operating band.

This paper introduces a dual-path Mach-Zehnder interferometer for determining refractive index and geometrical thickness of an optical plate. In this interferometer, two parallel incident beams are separated into two interference pairs which are then recombined to generate two interference signals. An optical plate is placed on the path of one wave of an interference pair, so the phase difference of the interference signals is a function of the plate, and the interferometer is thus able to determine the index and thickness of the plate. A setup constructed to realize the proposed interferometer is described. And the experimental results of applying this setup agree the validity of the interferometer.