Design of a 45∘-Inclined SIW Resonant Series Slot Array Antenna for $Ka$-Band

In this letter, a new type of resonant series slot array antenna for Ka-band for 45°linear polarization (LP) is described. Sixteen radiating slots, tilted at an angle of 45°, are separated by one-half guided wavelength due to use of the alternating inductive and capacitive load slot pairs. These alternating reactance slot pairs allow this novel antenna to achieve impedance matching, uniform field excitation, and suppression of grating lobes simultaneously. The antenna is designed and fabricated using substrate integrated waveguide (SIW) technology to overcome the drawbacks associated with conventional metallic waveguide antennas. The measured impedance bandwidth, maximum gain, and sidelobe levels are 2.7%, 15.64 dBi, and 15.36 dB, respectively, at the design frequency. The measured data are in agreement with the theoretical calculations and demonstrate the validity of the design technique for the proposed antenna structure.