A bidirectional planar monopole antenna array for WiFi/Bluetooth and LTE mobile applications

This paper presents a novel bidirectional planar monopole antenna array, with its feeding network, to apply for WiFi/Bluetooth and LTE mobile standards. The planar array is comprised of monopole antenna elements that utilise Archimedean spiral slots, inspired as resonance paths, in order to generate multi-band performance. Contrary to conventional structures, the feeding network is composed of three Wilkinson power dividers, for the purpose of providing synchronised output signals over the required frequency range, miniaturising dissipation losses and decreasing mutual coupling. Simulation and measurement results are presented for a single antenna element, an initial Wilkinson power divider and a four-element planar array, which reside on FR4 substrates. Successfully comparison between simulated and measured results verifies that the single antenna element achieves a 10 dB reflection coefficient from 2.2GHz to 2.9GHz, and the planar antenna array illustrates a 10 dB return loss bandwidth from 2.4GHz to 3.1GHz, which could cover WiFi/Bluetooth (2.45GHz) and LTE (2.6GHz) mobile applications. The proposed planar monopole antenna array also obtains large gain, high efficiency, narrow beam, low side lobe level and highly symmetric bidirectional radiation pattern in both E- and H-plane.