High‐Gain Endfire Periodic Leaky‐Wave Antenna Using Trapezoidal Elements on Double‐Sided Parallel Strip Line

ABSTRACT

This paper proposes a high‐gain endfire periodic leaky‐wave antenna (PLWA) based on a double‐sided parallel strip line structure. To overcome the inherent trade‐off between high gain and compact size, the antenna introduces a phase‐reversal crossover structure and a slot design in the trapezoidal unit cell, thereby effectively improving the propagation constant response and thus enabling more efficient endfire radiation, while significantly enhancing backlobe suppression and pattern purity in the endfire direction. A prototype centred at 8.5 GHz is fabricated and measured. Simulated and measured results are in good agreement, showing excellent overall performance with an impressive peak gain of 16 dBi, a high gain‐to‐length ratio of 7.2/ λ ₀ , and a compact overall size of 5.5 λ ₀ × 0.8 λ ₀ . While maintaining a simple structure, low fabrication cost, and ease of integration, this design achieves higher endfire gain, improved gain‐to‐length ratio, and better front‐to‐back ratio, making it a highly promising candidate for modern wireless communication systems, radar front‐ends and other platform‐integrated applications.