Synthesis of a Biasing Circuit for a Reconfigurable WiMAX Antenna (RWA) at 2.3 GHz

摘要

This research focuses on identifying the values of capacitors and inductors of a PIN diode biasing circuit to generate an optimum performance for a 2.35 GHz WiMAX antenna. The optimization involves the testing of a new range of capacitors between 47 and 330 pF and inductors from 18 to 56 nH on a fabricated reconfigurable WIMAX antenna (RWA). Advanced Design System (ADS) software is deployed to obtain simulation results using the touchstone block implementation technique. Four sets of the capacitor-inductor values are proposed based on the reflection coefficient (S_(11)) and transmission coefficient (S_(21)) to possibly achieve the best performance of the RWA. The four sets are; set 1: C = 47 pF, L = 56 nH, set 2: C = 100 pF, L = 56 nH, set 3: C = 150 pF, L = 56 nH and set 4: C = 330 pF, L = 56 nH. It is discovered that by simulation, set 2 produces the optimal S_(11) and S_(21) compared to the other combination sets. The resulting S_(11) and S_(21) is -26.61 and -0.046 dB, respectively. To further verify this, a complete set of biasing circuit consisting of a PIN diode, two 56 nH inductors and two 100 pF capacitors are integrated on the fabricated RWA. It is found that the combination of these components a PIN diode, produced a maximum gain of 6.28 dBi and a reflection coefficient of -15.08 dB at 2.35 GHz. Moreover, the these lumped component values also enabled the RWA to channel WiMAX signals directionally at the broadside, depending on the user locations.