Ultra-Wideband Narrow Wall Waveguide-to-Microstrip Transition Using Overlapped Patches

Area of Science:

• Electromagnetics and Wave Propagation
• Microwave Engineering
• Antenna and Array Technology

Background:

• Rectangular waveguide to microstrip transitions are crucial components in microwave systems.
• Existing designs often face limitations in bandwidth and integration with phased arrays.
• Ultrawideband (UWB) operation is increasingly demanded for advanced communication systems.

Purpose of the Study:

• To develop and characterize an UWB rectangular waveguide to microstrip line transition.
• To enable seamless integration of waveguide-fed elements in phased arrays.
• To compare the performance of top-side and bottom-side transition configurations.

Main Methods:

• Design of a novel transition utilizing three overlapped transversal patches.
• Excitation of patches to radiate into the narrow wall of the waveguide.
• Fabrication and back-to-back (B2B) measurement of both top-side and bottom-side transitions.

Main Results:

• Achieved fractional bandwidths of 21.2% (top-side) and 23% (bottom-side) across the LMDS and Ka bands.
• Measured maximum single transition insertion losses of 0.67 dB (top-side) and 0.85 dB (bottom-side) over the entire operating band.
• Demonstrated feasibility for λg/2 spaced phased array applications.

Conclusions:

• The proposed UWB transition effectively covers the LMDS and Ka bands.
• The design offers competitive bandwidth and low insertion loss performance.
• The transition is suitable for integration into λg/2 spaced phased arrays, offering flexibility with top-side and bottom-side options.