A new compact and low phase imbalance microstrip coupler for 5G wireless communication systems

Area of Science:

• Electrical Engineering
• Electromagnetics
• Microwave Engineering

Background:

• Microstrip couplers are essential components in RF and wireless communication systems.
• Existing coupler designs like rat-race and branch-line have limitations in size and performance.
• Novel coupler designs are needed to meet the demands of modern communication technologies.

Purpose of the Study:

• To design, fabricate, and measure a novel microstrip 180° coupler.
• To achieve a compact size and high performance, including wide fractional bandwidth and harmonic suppression.
• To validate the proposed coupler's suitability for 5G applications.

Main Methods:

• Mathematical analysis of meandrous coupled lines for coupler configuration.
• Optimization techniques to enhance coupler performance.
• Fabrication and measurement of the designed coupler prototype.
• Comparison of simulation and measurement results.

Main Results:

• A highly compact coupler with dimensions of 0.014λg².
• Achieved S21 of -3.45 dB and S31 of -3.75 dB at 1.61 GHz.
• Demonstrated a wide fractional bandwidth (FBW) of 56.2%.
• Exhibited harmonic suppression up to 2.17fo and low phase imbalance (180°± 0.023°).
• Magnitude unbalance of ±0.3 dB.

Conclusions:

• The novel meandrous line microstrip 180° coupler offers a unique combination of compactness and high performance.
• The design is suitable for 5G applications due to its operating frequency and harmonic suppression capabilities.
• Experimental validation confirms the simulation results, indicating the coupler's practical viability.