W-band phase measurement of reflected wave from diode grid for reflectarrays

Foreign Objects and Debris (FODs) must be removed from runways. Under the necessity of automatic continuous survey, we are investigating a new FOD detection system based on MilliMeter Wave (MMW) radar system connected by Radio-over-Fiber (RoF) lines. This RoF radar project is also interested in beam steering antennas such as phased array antennas. This paper describes a concept of a diode grid reflector antenna. We also introduce a phase evaluation system to measure the phase of reflected wave from the circuit boards in W band. The validity of the system is confirmed to compare between simulation and measurement. Moreover, we measured diode test boards to change the phase of reflected wave. As a result, we find that it is possible to change the reflection phase using switching diodes.