I. Introduction
With the recent technology developments and the emerging internet-of-things (IoT) concept, multiple integrated wireless/access solutions will serve to enable a long-term networked society. Radio frequency (RF) passives including inductors, capacitors, resonators, transmission lines, and antennas are essential parts of such a comprehensive RF system comprising integrated/off-chip components which are required for input/output impedance matching networks, feedings, and overall RF communication. Passive components with lower loss, smaller dimensions and tuning capabilities are highly demanded.