Design of Resistor-Loaded Reflectarray Elements for Both Amplitude and Phase Control

Conventional reflectarray elements have only phasecontrol property, and this letter presents novel reflectarray elements with both amplitude and phase control using proper resistor loading. Two amplitude-controllable reflectarray elements are presented with different phase tuning techniques. It is shown that the reflection amplitude for each element only depends on the resistor value, while the reflection phase only depends on the element size or the element rotation angle. Thus, the reflection amplitude and phase can be controlled separately, and a full 360 degrees phase range is achieved with a dynamic amplitude control over 10 dB. Both elements are fabricated andmeasured using a customized waveguide. The measured results agree well with the simulations, which verify the effectiveness of the proposed designs.