Generation of difference pattern from a linear microstrip patch array for the monopulse radar application

Abstract

This paper presents a new technique to generate difference pattern from a circularly polarized (CP) microstrip array antenna for monopulse radar application. The individual truncated corner radiators of the array are left-handed CP (LHCP). The difference pattern is generated by placing together the left and right side proposed single elements in opposite direction to each other along the y-axis with an inter-element spacing of 3λ/4. In order to achieve a stable radiation pattern with low sidelobe level over a resonating band, a uniform feed network is designed for the array. Finally, the proposed single element and the 4 × 1 array are designed, fabricated, and measured. The left-polarized element of the array structure, resonates at 5.90 GHz with good circular polarization properties. The array prototype resonates at 5.904 GHz with 3.60% impedance bandwidth. The array gives null depth greater than −30 dB at θ = 0 ∘ in different ϕ cuts. The proposed left-CP array has a gain of 9.48 dBic and a radiation efficiency of 77.50%. Moreover, the measured results matched well with the simulated results, which proves the effectiveness of the proposed approach for practical application.