A novel frequency scanning monopulse slotted waveguides array with enhanced scan sector

Abstract

A wide-angle frequency scanning narrow-wall slotted waveguide array antenna with monopulse function is designed for two-dimensional electrical scanning radar and communication systems. A novel slow wave waveguide formed by loading the periodic metal T-shaped sheets onto the narrow wall is used to enhance the frequency scanning angular sector of the edge-slotted waveguide traveling wave array. Two slotted waveguides with 35 radiation slots are arranged in a segmented frequency scanning structure to simultaneously achieve sum/difference patterns in the E-plan. The prototype antenna fabricated and welded by aluminum is composed of 70 × 8 radiation slots with an overall size of 425 mm × 45 mm × 10 mm. The measured results show that the designed array exhibits a frequency scanning angle range of 20.6 at a relative operating bandwidth of 10% with greater than 50% aperture efficiency. The measured sidelobe level of sum beam is less than −17 dB, and null depth of difference beam pattern is below-25 dB over operating frequency band. This structure can be used to design the electrical two-dimensional scanning array with a scanning sector greater than 20 × 80 .