A miniaturized harmonic suppressed 3 dB branch line coupler using H-shaped microstrip line

Abstract

The design of a compact size harmonic suppressed 3 dB branch line coupler using H‐shaped transmission line is presented. The circuit parameters of the proposed coupler are evaluated from the closed form equations. In order to validate the theoretical analysis, a prototype of proposed coupler operating at 0.9 GHz is fabricated and demonstrated. The size of the fabricated coupler is reduced by 64% of the conventional coupler with a comparable performance. The measured result not only shows the return loss and isolation better than 28 dB but also suppresses the unwanted spurious passband response up to third harmonic of the operating frequency. The measurement result shows good matching with the simulation result. © 2017 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:913–918, 2017

Compact Branch-Line Coupler With Harmonic Suppression Based on a Planar Simplified Dual Composite Right/Left-Handed Transmission Line Structure

“…Reactive area Harmonic suppression [4] Distributed Capacitors 38% Not shown [5] Asymmetrical T-Structures 12.2% Not shown [6] H-shaped transmission lines 36% Yes [7] Interdigitated shunt capacitors 26.8% Yes [9] CSRRs 40% Not shown [11] Symmetric polygonal folding lines 24% Not shown [12] Coupled lines 33% Not shown This work planar SD-CRLH TLs 26% Yes Figure 9. Phase difference and amplitude balance between S 21 and S 31 of the proposed branch-line coupler.…”

“…However, the conventional branch-line coupler will occupy large area especially at interest low frequency band. Therefore, various techniques have been proposed to miniaturize the size of the branch-line coupler [2][3][4][5][6][7][8][9][10][11][12]. In [2], the size of the coupler can be reduced significantly using lumped elements, but the lumped elements with precise value and high quality are not always available.…”

“…Then structures employing purely distributed elements are presented to replace the quarter-wavelength TLs. Most of them are realized by different forms of shunt loading, such as low or high impedance lines [3][4][5][6], interdigitated capacitor [7]. Other approaches using defected ground structures (DGS) [8,9], fractal geometries [10,11], coupled lines [12] are also introduced to effectively reduce the area.…”

A Dual-Band Branch-Line Coupler with Ultra-Wideband Harmonic Suppression

“…The conventional branchline coupler consists of four quarter-wavelength transmission lines and offers a single passband. Several methods have been utilized to realize harmonic suppression in single-band branchline couplers [1][2][3][4][5][6][7]. In [1], a coupled-line section was used to achieve a compact size and spurious rejection.…”

Miniaturized Branch-Line Coupler With Wide Upper Stopband Using Right-Angled Triangle Artificial Transmission Line

“…Although its size is 46% compared with its ordinary counterpart, and it rejects the first and second harmonic bands effectively, it has no advantages in systems required high-order suppression. In [3], a compact size harmonic suppressed 3 dB branch line coupler operating at 0.9 GHz is designed using an H-shaped transmission line. It can suppress the unwanted spurious passband response up to third harmonic of the operating band, and the occupied area is 36% of the conventional one.…”