RF-M/NEMS Switch Integrated Planar Inverted F-Antenna (PIFA)

We propose a novel multifunctional reconfigurable antenna (MRA) design using micro/nanoelectromechanical system (M/NEMS) switches. This single MRA operates over five frequency bands of GSM900, GPS1575, GSM1800, PCS1900 and UMTS2100. The reconfigurability in operating frequency is achieved by the activation of M/NEMS switches which are integrated with the antenna architecture. Summary of Research: An MRA enables a single antenna element to perform multiple functions by morphing its architecture thereby dynamically changing its properties (operation frequency, radiation pattern, polarization). This dynamic reconfiguration is achieved by integrated M/NEMS switches, and introduces important additional degrees of freedom in adaptive system parameters. As our recent results revealed, the use of MRAs in place of conventional “dumb” antennas, does not only provide reduction in system size but also remarkable performance gains (biterror-rate vs signal-noise-ratio) – up to 30 dB is possible depending on the channel conditions [1]. Radio frequency (RF) MEMS has created a significant technological impact due to their potential of revolutionizing RF and microwave system implementation for the next generation of communications applications. In particular, MEMS switches have become very popular with their excellent switching characteristics, i.e., very low insertion loss, very low power requirements, and high isolation which cannot be attained by semiconductor switches at low cost. However, several drawbacks still exist as well, including low-switching times which are in the range of 1-20 microseconds and high actuation voltages ranging from 20-80 Volts. More importantly, long-term reliability problems due mainly to two factors: dielectric charging and temperature sensitivity of the suspended movable metal membranes have been delaying use of RF MEMS in commercial applications [2]. The solutions to the problems of MEMS mentioned above lie in devices with smaller dimensions, so-called NEMS devices. The reduction in size results in excellent mechanical and thermal properties, which translate into better reliability, higher power handling capability, and faster switching. Given that NEMS switches do not only possesses the low loss behaviors of their MEMS counterparts, but also overcome the drawbacks of RF MEMS in terms of reliability, switching time and actuation voltages, the ultimate aim of this work is to integrate the MRA with sub-micron sized fast and reliable NEMS switches, i.e. nano-electrodes. Figure 1 shows the geometry of the MRA planar inverted-F antenna (PIFA), which operates over five commercial frequency bands of GSM900, GPS1575, GSM1800, PCS1900 and UMTS2100 in order to achieve the capability of global roaming with a single handset. The underlying design principle is to deliberately manipulate the PIFA patch structure, thereby changing the current distribution, to create three resonant current paths on the antenna surface, which deliver triband radiation behavior. Furthermore, the electrical lengths Figure 1: (a) Top view of the NEMS integrated MRA PIFA (b) Magnified view of the interconnecting NEMS switch/nano-electrode.