Free-space measurement of dielectric constants and loss tangents of low-loss materials using a microwave interferometer technique

Summary form only given. A microwave technique is implemented on a free-space microwave measurement system consisting of transmit and receive spot-focusing horn lens antennas, a network analyzer, mode transitions, and a computer. A planar sample (15.2 cm*15.2 cm in cross-section) is sandwiched between two composite reflectors for measurement of free-space S-parameters. Composite reflectors are made from 6 to 9 quarter-wavelength planar sheets of Teflon or fused quartz which are a quarter wavelength apart in free-space. Dielectric properties are calculated from the changes in resonant frequency and Q-factor due to the planar sample. Experimental results have been obtained at 16 GHz for several low-loss materials including polyvinyl chloride, boron nitride, and borosilicate glass.<>