Multi-Section Bow-Tie Steps for Full-Band Waveguide Polarization Rotation

Abstract

A new compact multi-section structure for broadband waveguide polarization rotation is presented. The twist component is based on cascading multiple steps with bow-tie shape geometry, which are progressively rotated between the input and output rectangular waveguides. The twists show an excellent performance in the full operating frequency band, which is controlled with the number of sections and their shapes and can be designed for any rotation angle. Moreover, the bow-tie sections are very short and compact and can be easily manufactured, being well-suited for satellite applications. The proposed configuration is shown with design tables and curves for different rotation angles. Two 90 twists in WR75 waveguide have been tested, showing measured return losses of 30 dB (one section) and 40 dB (two sections) from 10 to 15 GHz with a total length of 5.6 mm and 8.6 mm, respectively.Index Terms-Broadband waveguide polarization rotation, compact rectangular twist.

Arbitrary-Angle Single-Step Waveguide Twist for Quasi-Octave Bandwidth Performance

“…In the same work, simulations without experimental validation show how a return loss better than 40 dB could be reached for a 40% relative bandwidth by using additional sections at one or both sides of the basic twist. Similar results are obtained experimentally in [12] where a configuration including two bow-tie sections is used to achieve full band (40%) performance.…”

Native 2-D-FEM/Mode-Matching Formulation for Second-Order Symmetric Waveguide Devices

“…The main advantage of C N -MM combined with 2D-FEM is that it can be used to analyze structures which present rotational symmetry but do not exhibit first-order, axial (or reflection) symmetry. This is the case of the devices described in [26] and [40], shown in Figs. 9(a), (b), respectively.…”

“…9. Transition between two waveguides twisted 90 • taken from (a) [26] and (b) [40]. The inside of the waveguide is displayed, with transparency increased in the input and output waveguides to highlight the shape of the transformer.…”

On-Chip Integration of Orthogonal Subsystems Enabled by Broadband Twist at 220–325 GHz

“…Typically, two concepts are followed to design waveguide twists in rectangular waveguides: 1) gradual rotation [18], [19] and 2) a single [20], [21], [22], [23], [24] or multiple waveguide steps [25], [26], [27], [28]. Gradual or multiple-step rotations result in excellent matching, and thus a low return loss of as good as 30 dB can be achieved at the expense of elongated structures and fabrication complexity.…”

“…Gradual or multiple-step rotations result in excellent matching, and thus a low return loss of as good as 30 dB can be achieved at the expense of elongated structures and fabrication complexity. A multiplestep waveguide twist can be implemented in one piece [25], [26] or by stacking discrete waveguide sections [27], [28]. The latter is rarely used at THz frequencies due to its stringent alignment requirement, which is critical at these frequencies.…”