Ahmed A. Kishk

A quasi butler matrix with 6×6 beam-forming capacity using 3×3 hybrid couplers

A novel 6×6 beam-forming network with the topology structure and the properties similar to Butler Matrices is represented in this paper. Two 3×3 hybrid couplers are adopted as the substitution of traditional 3dB-90° hybrids to introduce the factor of 3 into in this network for changing the numbers of ports and beams from conventional 2n to 6. Moreover, one kind of 2×2 hybrid couplers with quasi-arbitrary phase-difference is utilized as well to eliminate using fixed phase shifters in this design for a smaller size and a lower loss. As an example, one proposed 6×6 network working at 5.8GHz has been designed, simulated, fabricated and measured. Good performances in matching, isolations, equal power divisions, coherent phase differences at all ports have been achieved. The possibility of improving structural flexibility of Butler Matrices by employing 3×3 hybrids is demonstrated in this paper.

Wideband Hybrid Coupler With Electrically Switchable Phase-Difference Performance

A wideband hybrid coupler with an adjustable output phase difference with equal power division is proposed. A compact, low-loss and low-cost reconfigurable transmission line with electrically switchable equivalent characteristic impedance and length is introduced and adopted in this design, which is based on a two-section quadrature hybrid structure. Additionally, only two bias points are needed in this hybrid coupler to operate six switches synchronously and provide three output phase differences; 90° and <inline-formula> <tex-math notation=LaTeX>

Two-Dimensional Butler Matrix Concept for Planar Array

90 pm a^{circ }

A Wideband Uniplanar Double-Ring Crossover With Balanced and Single-Ended Paths

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Wideband Filtering Unbalanced-to-Balanced Independent Impedance-Transforming Power Divider With Arbitrary Power Ratio

a le 30^{circ }

Vertical Coaxial-to-Ridge Waveguide Transitions for Ridge and Ridge Gap Waveguides With 4:1 Bandwidth

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Planar Balanced-to-Unbalanced In-Phase Power Divider With Wideband Filtering Response and Ultra-Wideband Common-Mode Rejection

a = 15^{circ }

Modeling and Design Empirical Formulas of Microstrip Ridge Gap Waveguide

</tex-math></inline-formula> and 30° are fabricated and measured for 2.4-GHz applications. Testing results demonstrate satisfying properties including the notably stable phase difference with an error less than ±6° over 30% frequency bandwidth. The presented hybrid couplers would be appropriate for Butler matrices to increase the number of possible beams, which will be more than the number of ports.