Abstract
Differential phase shifters are common circuits in communication systems where a fixed phase difference between two points within the circuit is required. Among the available technologies, waveguide phase shifters are preferred for applications such as antenna feed or beam-forming networks. Typical designs in the literature are devoted to specific phase delays such as 90° or 180°, but any phase shift might be required, and therefore a design procedure resulting in mechanically-related parameter fitting equations for any arbitrary phase difference would be advantageous. This paper presents a parametric design of full-band (40% relative bandwidth) waveguide differential phase shifters, providing polynomial equations for all design parameters in order to obtain arbitrary phase shifts between standard rectangular waveguides with equal physical lengths. The phase shift is achieved through the use of a multi-step ridge section together with a single width-step in the shift line. The proposed design procedure results in differential phase shifters with 25 dB of return loss and minimal physical length for any phase shift between 0° and 180°. To validate this parametric design process, two exemplary differential phase shifters with 30° and 140° phase shifts were measured, showing very good agreement with the simulated results.
Highlights
Differential phase shifters (DPSs) are common components in many applications where a fixed phase difference is required between two points within a circuit
180◦ DPSs are needed in most communication systems but, in general, any phase difference may be required for a specific application and DPSs with arbitrary phase shifts and stringent performances are still of importance for microwave designers
This work deals with ridge waveguide-based DPSs because the structures based on planar circuits, such as microstrip technology [1], despite having a compact size, exhibit noticeable insertion loss and low power handling capabilities that hinder their utilization in many antenna feed networks
Summary
Differential phase shifters (DPSs) are common components in many applications where a fixed phase difference is required between two points within a circuit. In a previous work [14], a ridge-based DPS was presented with full-band (40%) coverage in Ku-band and 25 dB of return loss showing ±2.5◦ and ±3.5◦ shift errors for a 90◦ -DPS and 180◦ -DPS respectively This structure, as presented in [14], can be scaled to other frequency bands, it cannot be straightforwardly modified to meet other phase difference values unless the design process is restarted. Focusing on the concepts of minimum physical length and the same number of matching steps for all phase difference values, in this paper we present a parametric study of a ridge-based differential phase shifter resulting in fitting equations that enable a fast and accurate design process for obtaining a DPS with any arbitrary phase difference between the shift and reference lines with equal physical lengths.
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