High-Endfire-Gain Dielectric Image Line-Based Periodic Leaky-Wave Antenna With Planar Feeding

A high-endfire-gain periodic leaky-wave antenna (LWA) based on dielectric image line (DIL) and fed by a planar transition is proposed. The unit cell of the periodic DIL consists of two dielectric blocks with different permittivity, and space harmonics (SHs) are then generated. A revised formula for phase constant of the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</i>th space harmonic is introduced for the periodic structure. Although the proposed antenna is grounded, it obtains high endfire gain with a small cross section and experiences a slight deflection beam direction, effectively addressing the issue of conformity between the endfire antenna and metal surfaces. The maximum measured endfire gain is 16 dBi, achieved with a cross-sectional area of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\text {0.34}{{\lambda }_0} \times \text {0.13}{{\lambda }_0} \times \text {19}{{\lambda }_0}$</tex-math></inline-formula>. The antenna can achieve good matching within the frequency range of 14.4 GHz to 16.0 GHz.