RCS Enhancement of Millimeter-Wave LTCC Van Atta Arrays With 3-D Printed Lenses for Chipless RFID Applications

In this letter, we present a new method to enhance the radar cross section (RCS) of Van Atta arrays, which can be used in chipless radio frequency identification tags operating in millimeter-wave frequency bands. Small planar low-temperature co-fired ceramic (LTCC) Van Atta arrays, which are durable and can operate in harsh environments, are combined with 3-D printed lenses to increase or modify the shape of their RCS by up to 10 dB. The lenses are uniform in one direction to maintain a wide RCS angular range of the underlying Van Atta arrays. They are manufactured using an affordable 3-D printing stereolithography process using high-performance resin. The resulting manufactured and measured Van Atta retrodirective arrays integrated with lenses exhibit measured RCS levels up to −28 dBsm at 24 GHz frequency. Moreover, the proposed approach allows LTCC Van Atta tags to be easily modified and reused by exchanging their lenses to adapt them to a new application. To the best of the authors' knowledge, this is the first time an experimental evaluation of lenses combined with Van Atta arrays has been presented. This novel technique can also be integrated with other RCS enhancement methods to further increase RCS levels.