Electronically reconfigurable parasitic antenna array for pattern selectivity

Abstract

Antenna arrays are commonly used to achieve high gains and beam steering, but they require complex feeding networks. For applications demanding moderate antenna gains (≃6 dB) and planar radiating structures, printed Yagi-Uda antennas can offer many advantages, but clearly, they cannot cover the whole azimuth plane. A symmetric structure made of two Yagi-Uda antennas with two active elements, a shared reflector and two directors of variable length is here presented and demonstrated to have switched beams that cover all the azimuth plane. By lengthening the physical lengths of the directors, they turn to act as reflectors: as a result, this antenna system has the ability to switch between broadside, bidirectional end-fire and two opposite end-fire patterns. The feeding is provided by a balanced parallel strip-slot line without the need for a balun section and thus reducing the overall size of the antenna. A modified design is also presented, obtained by adding a reflector board which allows for higher gains and focused radiation reconfigurability in the half-space. Simulated and measured results of both designs are reported showing good agreement. The antenna has a compact size, wideband characteristics and directive pattern reconfigurability.

Keywords

• Yagi antenna arrays
• broadband antennas
• antenna radiation patterns
• antenna feeds
• baluns
• beam steering
• reconfigurable parasitic antenna array
• pattern selectivity
• beam steering
• complex feeding networks
• planar radiating structures
• printed Yagi-Uda antennas
• azimuth plane
• symmetric structure
• active elements
• shared reflector
• directors
• variable length
• switched beams
• physical lengths
• antenna system
• bidirectional end-fire
• opposite end-fire patterns
• balanced parallel strip-slot line
• reflector board
• focused radiation reconfigurability
• directive pattern reconfigurability