Design of integrated wideband WR34-band diplexer-antenna array module for exploration of monolithic metal 3-D printing for space applications

The design of a wideband diplexer integrated with a 16-slot Continuous Transverse Stub (CTS) antenna array is presented. The diplexer-antenna array module covers the whole WR34 band. The Tx and Rx bands cover 21.7–26 and 27.5–33 GHz ranges, respectively. The diplexer is designed to have a 100 dB attenuation in the stopband and 40 dB isolation between the channels. The antenna array has a high gain, between 26.9 and 31 dBi, at the lowest and highest frequencies. For the preliminary exploration of monolithic metal 3-D printing of complex geometry integrated RF front ends, two prototypes were manufactured in AlSi10 Mg. One-piece fabrication eliminates complicated assembly, enhances reliability, and reduces weight, which is more desirable for space applications. Due to several factors, namely, an unpolished inner surface and imperfect printing quality, the diplexer had a poor measured performance. The measured results of the antenna array had a relatively better agreement with simulations. Although, the realised gain was affected by the much lower effective conductivity of the unpolished 3-D printed material. Hence, the measured realised gain was between 27.8 and 30.9 dBi in the 29–33 GHz range.