Miniaturized Side-firing Bidirectional Antenna Array Based on Periodic Cross-meander Metallic Lines

A side-firing bidirectional antenna array based on a pair of periodic cross-meander metallic lines is proposed in this paper, which exhibits the advantages of compact design and high aperture efficiency. A novel meandered-line element is introduced to reduce the width of the bidirectional antenna while maintaining its effective bidirectional radiation capability. Furthermore, using a novel dual-layer periodic array design approach, the bidirectional antenna array achieves a uniform aperture amplitude distribution while maintaining a compact structure. A prototype is fabricated and measured to validate the design strategy. The overall dimensions of this antenna array are only 1.42λ<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</inf> × 0.16λ<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</inf> × 0.02λ<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</inf> (λ<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</inf> is the free space wavelength at the center frequency), and the -10 dB impedance bandwidth ranges from 2.4 GHz to 2.5 GHz. The proposed antenna array exhibits a narrower width and a higher gain-to-area ratio.