Directional thermal emission from a leaky-wave frequency selective surface

Abstract

We design, fabricate, and characterize a Frequency Selective Surface (FSS) with directional thermal emission and absorption for long-wave infrared wavelengths (LWIR). The FSS consists of an array of patch antennas connected by microstrips, the ensemble of which supports leaky-wave type modes with forward and backward propagating branches. The branches are designed to intersect at 9.8 μm, and have a broadside beam with 20° FWHM at this wavelength. The absorption along these branches is near-unity. Measurement of the hemispherical directional reflectometer (HDR) shows good agreement with simulation. The ability to control the spectral and directional emittance/absortpance profiles of surfaces has significant applications for radiation heat transfer and sensing.