Bidirectionally-Fed Slow-Wave Substrate-Integrated Waveguide Monopulse Slot Array Antenna With Gain Enhancement

A slow-wave substrate-integrated waveguide (SW-SIW) monopulse slot array antenna with gain enhancement is proposed. The radiating part of the monopulse antenna is a SW-SIW leaky wave slot array, which is composed of two layers of Rogers 5880 dielectric substrates. To realize slow-wave effect, periodic metallized via holes are embedded in the lower substrate to increase the effective permittivity of SIW, forming the SW-SIW with slowed phase velocity and shortened guided wavelength. The number of radiating unit cell of the SW-SIW slot array can be twice as many as normal SIW slot array with the same radiating aperture, increasing the radiation efficiency and the gain. A SW-SIW monopulse slot array with 20 units is designed, and compared with a normal SIW monopulse slot array with only ten units occupying same radiating aperture. The sum and difference patterns of the SW-SIW monopulse slot array are generated and the gains are 2.5 and 2.1 dB higher than the normal SIW monopulse slot array. A prototype of the SW-SIW monopulse slot array antenna is designed, manufactured, and measured. The feeding network is a hybrid ring connected with two identical RF cables, providing differential feed for the leaky wave slot array. The measurements agree the simulations well, verifying the design concept.