Design of coaxial aircell fixture for the measurement of electromagnetic properties

Abstract

Abstract-Coaxial aircells are designed and fabricated to measure the electromagnetic properties of ferrite materials in the frequency range from 1 MHz to 3.6 GHz. These Sparameters are actually measured connecting the aircell to a vector network analyzer (VNA).The electromagnetic properties such as complex permittivity and complex permeability are extracted using Nicolson-Ross-Weir (NRW) method and also suitable air-gap corrections are made. To optimize the measured result and to estimate the error, the aircells are characterized in terms of their phase constant and resistivity of the aircell conductor. The measurements clearly showed that the electrical length is longer than the mechanical length of the aircell at all frequencies. The arithmetic mean of the resistivity of aircell which is of 7mm line size and 60mm length is about 66 nΩm. This paper presents a simple method by which the phase constant and resistivity of the aircell can be determined accurately. This is done with the transmission measurements made using a VNA.