Mechanically frequency reconfigurable antenna for WSN, WLAN, and LTE 2500 based internet of things applications

In this paper, the concept of a novel mechanically reconfigurable antenna with spectral diversity, for internet of things (IoT) applications is presented. The prototype consists of a rectangular microstrip patch antenna placed upon a dielectric slab with four end-to-end cavities that are perceived as binary bits. The status of each bit depends on the material filling it. Since four cavities are included in proposed system, a total of 16 combinations, each yielding unique impedance characteristic, are exhibited. Here, FR4 epoxy (epsilon(r)= 4.4 and tan delta= 0.02) is used as substrate with 2.4 mm thickness. The same material is used to fill the cavities in one case, while, in the second case the cavities are filled with Rogers RT/duroid 6010/6010LM (tm) material that has dielectric constant, 10.2. It is shown that by using a higher dielectric constant material as filler, the range of variation of resonant frequency can be increased. In both cases, the prototype exhibits capability to reconfigure its operating bandwidth from 2.4GHz WLAN (2400-2480 MHz) to LTE2500 (2496-2690 MHz). Besides, for some combinations, the prototype covers a frequency span beyond LTE till 3000 MHz for wireless-sensor-network based applications. One among the potential application of the proposed design as a chipless RFID tag is also discussed in this work.