122 GHz Aperture-Coupled Mushroom EBG Antenna in LTCC Technology

This paper presents two variants of a Mushroom Electromagnetic Bandgap (MEBG)-based antenna with an extremely thin antenna substrate, yet a high bandwidth-efficiency product. An MEBG unit cell (UC) exhibits two interesting electromagnetic (EM) properties, namely, it shows a strong compression of resonance frequencies and it acts as a high impedance surface in specific frequency bands, thereby transforming surface waves into space waves. The EM properties of an MEBG UC are optimized around 122 GHz by simulating its dispersion diagram. Thereafter, a 4X4 and 6X6 matrix of the optimized MEBG UCs are used to form two multilayered antennas in Low Temperature Co-fired Ceramic (LTCC) technology. Both antennas are fed using aperture coupling and a stripline-to-grounded coplanar waveguide signal transition. Simulation and probe-based measurement results of the antennas are presented between 110 and 150 GHz.