RF-MEMS tunable filters on low-loss LTCC substrate for UAV data-link

In this paper, a fixed-frequency filter and two RF-MEMS based frequency-agile filters at Ku-band are demonstrated. All filters are designed in a so-called substrate integrated cavity (SIC) topology, and they are processed in LTCC (low temperature co-fired ceramics) DuPont 943 substrate. The tunable filters are steered over frequency by means of coplanar stubs, whose electrical length is adjustable. The tunable stubs are RF-MEMS cantilevers processed on silicon. The paper describes the design of the fixed and tunable filters, and it proposes a hybrid integration concept of the silicon chips onto the ceramic board of the filters. Finally, all presented structures are characterised by on-wafer measurements, and they are assessed in regard to the expected performance.