No Frequency Reuse: Wearable Steerable MIMO Microstrip Antenna Array for Mobile Ad Hoc Applications

Abstract

Aim: The principle of eliminating the frequency reuse in the mobile Ad Hoc system among the sectors of the unit cell using Multi Inputs Multi Outputs (MIMO) antenna array is investigated in this paper. Antenna Design: The size of the proposed antenna array is 10×10 cm2 to obtain a bandwidth around 1 GHz. The single antenna element is constructed from sub-patches that are connected with feeding network through pin diodes, as switches, that are mounted on an FR-4 substrate. Antenna Performance: The antenna elements are characterized from 0.8 GHz to 2 GHz in terms of S-parameters and radiation patterns with different switching OFF/ON categories. Methodology: A numerical investigation based on Finite Integral Techniques (FIT) of Time Domain (TD) formulations is conducted using CST MWS to evaluate the antenna performance. A Frequency Domain (FD) solver based on CST formulations is conducted for validation. Results: It is found the antenna shows insignificant coupling around 1.2 GHz and 1.6 GHz. Furthermore, the radiation patters of the antenna are found to be in the end fir direction with phase change of about 120o among antenna sectors. The antenna provides absolute gain of 2 dBi at 1.2 GHz and 2.9 dBi at 1.6 GHz. It is found that the proposed antenna behaves like highly directive end fire antenna at the main lobe direction around 1.6 GHz. Moreover, it is found that the antenna array exhibits insignificant coupling among each other around this frequency. Conclusion: The performance and structure of the proposed design allows the use with wearable Ad Hoc mobile systems without the need for frequency reuse by steering the radiation patterns of the antenna sectors through switching antenna branches. Finally, an excellent agreement has been achieved between the regarded results from TD and FD solvers.