Transmission coefficient estimation based on power measurements using a hybrid coupler

In this work, we attempt to develop a method that measures the transmission coefficient of a microwave device. This method combines a simple microwave circuitry and a signal processing algorithm. The measurement apparatus includes a signal source, a directional coupler, a 180 degree hybrid coupler and two power detectors. Though only magnitudes of transmitted power are measured, the phase information of the device-under-test can be estimated via signal processing techniques in conjunction with known knowledge about the measurement system. Preliminary measurement results demonstrate that the proposed method can acquire results similar to the ones measured from a network analyzer. The system is particularly attractive since the overall cost is very inexpensive comparing to the network analyzer.