Compact planar microstrip branch‐line coupler using equal difference structure

Abstract

microstrip line inductance L ð Þ slightly decreases with the increase of "n" due to the slight increase of mutual inductance (opposite polarity) between the microstrip line and ground plane.In Figure 7, the effect of varying the dimensions ðp5d5gÞ on the equivalent electrical parameters are illustrated while "n" is fixed at 7 mm. The intrinsic capacitance C c ð Þ and inductance L c ð Þ of the CSRR unit cell decreases because of the expanded capacitive gaps and reduced electrical path length of the inner disc conductors connecting to the ground plane. Besides this, the inductance L ð Þ of the microstrip line increases due to the decreasing of mutual inductance (lesser magnetic flux linkage to the ground plane) between the CSRR and microstrip line. This property can be used to control the pole frequencies. CONCLUSIONIn this letter, a more accurate electrical parameter extraction method of rectangular CSRR is proposed for UWB range which is based on the information of four characteristic frequencies found in the scattering response. The proposed technique is used for a detailed parametric analysis of CSRR unit cell. This present study will be helpful for optimization of CSRR-based microstrip designs. ACKNOWLEDGMENTAuthors are personally thankful to Mr. L. Murmu of ISM, Dhanbad for supporting this work.ABSTRACT: A compact planar microstrip branch-line coupler using equal difference structures was implemented and measured. Using the equal difference structure effectively reduced the quarter-wavelength microstrip line and minimized the branch-line coupler dimension as a result of a novel triangular profile of the structure streamlining the circuit area. Compared with that of conventional planar microstrip branchline couplers, the optimized area of the proposed coupler was reduced by 84.2% at a 900 MHz operating frequency. The measured insertion loss, isolation, and return loss performances achieved superior results than 3.9, 23, and 16 dB, respectively, and the measured phase difference between the two output ports was 908 6 0.18. Notably, a coupler using equal difference structures can be implemented in standard printed circuit board processes without any lumped elements, bonding wires, or via-holes, easing integration with wireless communication systems.

Extremely compact microstrip branch‐line coupler with a novel fold structure

“…Currently, all cost‐reduction efforts, including size reduction and low‐cost fabrication, are focused on components of modern wireless communication systems; therefore, several studies have proposed miniaturized branch‐line coupler designs using various techniques in recent years . ‐ …”

“…In Ref. , a triangular stub line structure, referred to as the equal difference structure, was proposed to shorten transmission lines. The novel triangular stub line structure prevented the overlapping of stub lines to reduce coupler size.…”

Miniaturized Lumped-element LTCC Quadrature Hybrid with LC Stacked Structure

“…Table 1 compares the measured results with implementations in [2][3][4][5][6]. Proposed work's return loss (RL), insertion loss (IL), phase imbalance, amplitude imbalance at the operation, fractional bandwidth (FBW), and size are compared with [2][3][4][5][6], respectively. The proposed hybrid has the widest FBW with an RL better than 14.2 dB.…”

“…The proposed hybrid has smaller IL, phase imbalance, and amplitude imbalance than [2][3][4][5][6], which indicates its good performance. Furthermore, the stacked structure has a smaller size than [2][3][4][5][6] in Table 1.…”

“…Over the years, several efficient approaches have been reported for miniaturizations [2][3][4][5][6]. In [2], a compact planar microstrip branch-line coupler using equal difference structures is proposed, which reduces the length of quarter-wavelength microstrip line and thus minimizes branch-line coupler dimension. A compact harmonic suppressed 3 dB coupler using H-shaped transmission line is proposed in [3] with a size reduction of 64%.…”