The motivations for developing tunable filters might be traced to three factors: cost, weight, and power dissipation. In modern satellite communications, for instance, where an enormous number of filters are employed, there is extreme interest in minimizing both manufacturing cost, weight, and power consumption. The potential of MEMS technology to permit the batch fabrication of tunable filters is rather appealing, as these might in principle obviate the need for expensive manual tuning in favor of electronic tuning during system integration and alignment, thus reducing cost.
On the other hand, the availability of inexpensive tunable filters opens up new opportunities, not only for novel systems architectures, but, by increasing filter functionality, thus reducing the number of individual filters needed, which reduces overall weight. Finally, since MEMS avails itself of electrostatic schemes for tuning, the power dissipation incurred in implementing tunability is negligible. In this section we study the cases of millimeter-wave micromachined tunable filters demonstrated by Kim et al.