A Pattern-Reconfigurable, Compact, Wideband Filtering Directive Dipole Antenna Enabled With Mixed Couplings

A pattern-reconfigurable, compact, wideband filtering directive dipole antenna enabled with mixed couplings is presented. Due to the mixed couplings in a single-fed multiple-element dipole antenna, the generated phase differences between resonators contribute to the filtering response and directive radiating performance simultaneously within a close element spacing. Based on this design methodology, two switchable opposite directive endfire states can be accomplished by controlling the ON/OFF operating states of the four PIN diodes integrated into a pair of custom-designed parasitic elements. A prototype operating at about 1.2 GHz is designed, fabricated, and measured. The measured results, in good agreement with simulated results, demonstrate that the antenna exhibits 22.4% wide operational bandwidth and 4.5 dBi realized gain values at a compact size of 0.21λ₀ × 0.33λ₀. A good out-of-band rejection level of 12 dB is also achieved in both states. The proposed antenna can be employed in space-limited communication systems, e.g., vehicle-to-vehicle scenarios and indoor wireless network systems.

I. Introduction

The trend of miniaturization and multifunction integration, complying with the rapid evolution of wireless communication systems, is the mainstream of antennas [1]. Hereby, filtering antennas and reconfigurable antennas have emerged and gained much attention recently due to their unique performance characteristics.