Compact Full Ka-Band Waveguide Directional Coupler Based on Rectangular Aperture Array with Stairs.

Area of Science:

• Electrical Engineering
• Electromagnetics
• Microwave Engineering

Background:

• Waveguide directional couplers are essential components in microwave circuits.
• Achieving compact size and broad bandwidth simultaneously presents a significant design challenge.

Purpose of the Study:

• To present a compact 3 dB waveguide directional coupler.
• To achieve full waveguide bandwidth operation with enhanced performance characteristics.

Main Methods:

• The proposed coupler utilizes a pair of parallel rectangular waveguides.
• A unique stairs structure is incorporated within the coupling region.
• A rectangular aperture array is implemented on the broad wall of the waveguides.

Main Results:

• The coupler demonstrates a return loss better than 17.46 dB over the full waveguide bandwidth.
• Coupling strength ranges from -2.74 dB to -3.80 dB, with power-split unbalance within 0.76 dB.
• Excellent isolation exceeding 20.82 dB was achieved in a compact coupling region of 15.82 mm.

Conclusions:

• The proposed stairs-structured waveguide directional coupler offers a compact and broadband solution.
• The design meets key performance metrics including coupling flatness and return loss.
• Experimental validation confirms the effectiveness of the novel structure for microwave applications.