Compact and Gain-Improved Normal-Mode Crossed Meander Dipole Array With Bidirectional Patterns

In this letter, a planar compact and gain-improved normal-mode crossed meander dipole array with bidirectional patterns is presented. First, a novel design method based on the theory of dipole array is adopted. The theory indicates that the width of the dipole array poses less effect on the directivity than the period of dipoles. Then, the theory is applied and demonstrated in the proposed serial-fed dipole array design. The dipoles are meandered to reduce the array width. The dipole array is constructed serially to two crossed meander lines. The reduced width of the dipole array will lead to a rising period of dipoles, improving the gain simultaneously. Thus, an optimal gain-to-area (G/A) value can be obtained by modifying the width of dipole array. Our proof-of-concept design is validated by a fabricated prototype. The operating bandwidth is from 2.40 GHz to 2.50 GHz. The proposed planar bidirectional dipole array features a compact size of 1.42<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">λ</i><sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub>×0.16<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">λ</i><sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub>×0.02<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">λ</i><sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> operating at the center frequency of 2.44 GHz, where <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">λ</i><sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> denotes the free-space wavelength. An outstanding G/A of 16.99 is obtained, demonstrating the feasibility of the proposed design strategy for compact and gain-improved bidirectional dipole arrays. Compared to existing works, the proposed bidirectional dipole array exhibits a smaller width and higher G/A value, which would hold great promise in long and narrow communication scenarios, such as tunnels and bridges.