Angle resolved microwave spectrometer for metamaterial studies

Abstract

We describe an angle resolved microwave spectrometer (ARMS) based on a planar waveguide scattering chamber, capable of acquiring the angular distribution of TE polarized microwaves scattered from samples centered within the chamber. The spacing between the upper and lower conducting circular plates is 0.4 in. (∼1 cm), which, with the associated X-band waveguide adapters, fixes the frequency of operation of the ARMS to be optimally within the X-band frequency range (8–12 GHz). Microwave energy can be injected either as an apertured beam via an extended arm connected to the chamber, or via an antenna located in the center of the chamber. Power is detected at a waveguide adapter located on the periphery of the chamber, attached to a rotating arm that has an angular range of 180°. A computer controlled stepper motor attached to the rotating arm facilitates angular scanning with the data acquired at every angle in an automated fashion. The ARMS has excellent reproducibility and signal-to-noise characteristics, making it ideal for characterizing the refraction properties of metamaterial samples, or as a probe of the interaction between antennas and metamaterial substrates.