An investigation on frequency selective antenna interface based on optimization approach

New long range wireless standards, such as LTE-NB, for Internet-of-Things (IoT) devices have very challenging requirements for power consumption, however, relax, somewhat, linearity requirements of the receiver. Efforts to make low power, low cost and compact devices rise new challenges in the whole level of design including antenna interface which is the entry block of each transceiver chain. High system efficiency and selectivity as close as possible to antenna interface are key design criteria. This issue, demands the designer to ensure the optimality of the antenna interface. This paper presents a precise method for designing two-port impedance matching filters loaded by arbitrary frequency dependent loads. Above mentioned strict constraints favour using fewer number of elements and thus reduce potential losses. A design technique to quickly evaluate all possible topologies from a limited set of elements is presented. The idea is implemented in MATLAB and verified by a design example including lossy elements and practical terminations.