A Method for Direct Impedance Measurement in Microwave and Millimeter-Wave Bands

A novel method for direct impedance measurement using a common vector network analyzer (VNA) is introduced and experimentally verified. In commonly used methods, the input impedance or admittance of a device-under-test (DUT) is derived from the measured value of its reflection coefficient causing serious inaccuracy problems for very high and very low impedances. The proposed method makes it possible to measure a quantity that is, in the ideal case, directly proportional to the value of input impedance or admittance of the DUT, enabling accurate and stable measurement of impedances that are extremely different from the common 50-Ω reference impedance. The method can significantly reduce errors caused by the VNA.