Analysis and design of slotted substrate integrated waveguide antenna on cylindrical surface

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2014
Bayraktar, Ömer
This thesis presents novel traveling wave conformal shunt slot arrays on cylindrical substrate integrated waveguide (CSIW) placed on a cylindrical surface in the circumferential direction at K-band. Mutual couplings of longitudinal slots on broad wall of CSIW are formulated and active admittance formulas of the slots are derived which are used in Elliott’s design procedure to design slotted CSIW arrays. The designs are carried out at 25 GHz using non-uniform and uniform slot separations. The non uniform slot array allocates 16 slot elements near resonance where element separations are determined to compensate different spatial phase delays of each element to increase directivity. The slot excitation amplitudes are determined by -20 dB side lobe level (SLL) Taylor distribution using aperture projection method. However, -20 dB SLL is not achieved because of large slot separations. Hence, slot lengths are optimized further to increase bandwidth for beam steering applications at the expense of increasing SLL. Three different uniform slot arrays are designed with 25 slot elements to obtain pencil beam pattern with low SLL using aperture projection method and genetic algorithm. The required slot excitation coefficients are achieved by using slots with large deviations from resonance. Both uniform and non-uniform slot arrays are fabricated using standard printed circuit board (PCB) process. The antennas are measured and about 10° beam steering in H-plane is obtained when frequency is swept between 24-26 GHz in the non-uniform slot array. Pencil beam pattern with desired -20 dB SLL is achieved at 25 GHz in the uniform slot array.

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Citation Formats
Ö. Bayraktar, “Analysis and design of slotted substrate integrated waveguide antenna on cylindrical surface,” Ph.D. - Doctoral Program, Middle East Technical University, 2014.