Effects of bonding-wire interconnect on electrically tunable microstrip antennas

The objective of this paper is to discuss bonding-wire effects on microstrip antennas for miniaturization and tuning of the resonant frequency. When varactor diodes are used as capacitive loads for the antenna, it allows reducing the size of the antenna with an added feature of tunability. Change of resonant frequency of microstrip antenna is also affected by inductance of bonding- wire, which is used for assembly in this work. Varactors and bonding-wire inductance are characterized by their equivalent circuits and incorporated as lumped elements in the Finite Difference Time Domain method. The reactive loading of bonding-wire has a large significant effect on the resonant frequency of microstrip antenna. The inductance of bonding-wire shifts resonant frequencies of microstrip antenna to be shifted to lower values but the tuning range is not affected. The size reduction and tunability of the antenna are demonstrated experimentally and theoretically using varactor and bonding-wire interconnects.