Reconfigurable multi-band phased-array antennas are receiving a lot of attention lately due to the emergence of RF MEMS (micro-electro-mechanical systems) switches [1-6]. A MEMS-switched reconfigurable multi-band antenna is one that can be dynamically reconfigured within a few microseconds to serve different applications at drastically different frequency bands, such as communications at L-band (1-2 GHz) and synthetic aperture radar (SAR) at X-band (8-12.5 GHz).
Reconfigurable Patch Module (RPM): We investigated the design and fabrication of a dual L/X-band reconfigurable antenna. Microstrip antenna elements were chosen due to their inherent lowprofile, which is suitable for satellite and UAV applications. We used RT/duroid 5880 material with a dielectric constant of 2.2 and a loss tangent of 0.0009 at 10 GHz. Two material thicknesses were investigated: 0.062" and 0.125". The material thickness must be chosen carefully, since it controls both the bandwidth and array scanning performance. The thicker the material, the more bandwidth, particularly at the low frequency end. However, if the substrate becomes too thick, surface waves are generated and array scanning performance and efficiency is lost. Figure 1 shows a picture of the 3x3 RPM fabricated on 0.125" duroid. The patches are 0.370" square and separated by 0.590" on center. Interconnecting tabs are 0.050" wide and 0.085" long. The "reconfigurable" antenna was actually fabricated as two separated prototypes (OPEN and CLOSED configurations) for testing in the laboratory.
Jorge L Polentino U