Design of High-Directivity Wideband Microstrip Directional Coupler With Fragment-Type Structure

• A novel design for a microstrip wideband directional coupler is proposedby using fragment-type structures. The use of a fragment-type structuremay provide satisfactory flexibility and excellent performance. For agiven design space, a fragment-type wideband coupler can be designed byfirst gridding the space into fragment cells and then metallizing thefragment cells selected by a multi-objective optimization searchingalgorithm, such as a multi-objective evolutionary algorithm based ondecomposition combined with enhanced genetic operators. Fordemonstration, a 20-dB wideband microstrip directional coupler isdesigned and verified by test. A 45% bandwidth centered at 2 GHz hasbeen measured in terms of maximum variation of 0.5 dB in the 20-dBcoupling level. In the operation band, the designed coupler hasdirectivity above 37 dB, and a maximum directivity of 48 dB at 2 GHz. Inaddition, some technique aspects related to multi-objective optimizationsearching, such as effects of design space, control of coupling level,and efficiency consideration for optimization searching, are furtherdiscussed. Fragment-type structures may also be used to designhigh-performance wideband directional couplers of tight coupling level.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Elektroteknik och elektronik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Electrical Engineering, Electronic Engineering, Information Engineering (hsv//eng)

Nyckelord

Fragment-type structure

microstrip directional coupler wideband design

multi-objective evolutionary algorithm based on decomposition combined with enhanced genetic operators (MOEA/D-GO)

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