Theoretical and experimental investigations of a bilevel 'Lange' coupler

Sachse, K.; Sawicki, A.; Jaworski, G.

doi:10.1109/mikon.1998.737914

Cited by 7 publications

(6 citation statements)

References 6 publications

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“…The following symmetric couplers ought to be distinguished among the others: 1) high-directivity coupler using coplanar waveguide technology [8]; 2) multilayer monolithic-microwave integrated-circuit (MMIC) broadside coupler with a symmetric structure of four strips, of which two are located on the top surface of the multilayer polyimide film and the other two on an intermediate layer in the polyimide film [12]; 3) modified four-strip Lange couplers with two pairs of two strips located in two levels of metallization [3], [13]; 4) re-entrant coupler using thin dielectric layer with a floating potential strip [9]. However, the couplers designed in the technology of both coplanar lines and re-entrant coupled lines do not allow having the outputs from the same side of the coupler.…”

Section: Introductionmentioning

confidence: 99%

Quasi-ideal multilayer two- and three-strip directional couplers for monolithic and hybrid MICs

Sachse

Sawicki

1999

IEEE Trans. Microwave Theory Techn.

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In this paper, the properties of multilayer two-and three-strip asymmetric coupled lines are described using their coupled-mode parameters. Examples of quasi-ideal, microstrip, and coplanar directional couplers designed in monolithic and hybrid microwave integrated-circuit technology, consisting of various layered structures of bilevel and trilevel coupled lines, are presented together with experimental results for two 3-dB couplers on ceramic-filled polytetrafluoroethylen and polyimide laminates.

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Section: Introductionmentioning

confidence: 99%

Quasi-ideal multilayer two- and three-strip directional couplers for monolithic and hybrid MICs

Sachse

Sawicki

1999

IEEE Trans. Microwave Theory Techn.

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“…In the case of branch-line couplers, several dual-band schemes are proposed in the literature [2][3][4][5]. These include the use of left-handed transmission lines [2], crosscoupled branch-line structure [3], and the use of stub lines at the input ports [4] or at the center of the branches [5].…”

Section: Introductionmentioning

confidence: 99%

“…The coupled-line type is generally applied to the hybrid couplers, because its return loss and directivity exhibit more wideband than those of the hybrid coupler with lumped elements such as inductor and capacitor [1]. However, a general coupler with coupled lines is requested to have improved performances of return loss and directivity, because its performances get worse in the high frequency band [2][3][4][5]. To resolve the problem of poor directivity, compensating technique by the use of shunt capacitor to ground was reported [4].…”

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Compensated LTCC broadside coupler design with branch lines

Noh

Uhm

Yom

2008

Micro & Optical Tech Letters

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magnetic materials, the amplitude of current induced to the antenna is smaller than with dielectric materials. Because the main radiation mechanism is through the electric field fringing at the patch ends, the induced current contributes mainly to the energy stored in the antenna volume. Thus, the advantages of magnetic materials stem from the favorable antenna geometry and feed technique. The key findings have been qualitatively validated using numerical simulations. INTRODUCTIONThe directional couplers for many microwave circuits and systems are widely used to distribute a microwave signal or to combine signals, and are available for various purposes. Low-temperature cofired ceramic (LTCC) directional couplers that are realized with parallel coupled lines on the same layer are hard to be realized for tight couplings because of manufacturing constraints of very small spacing between coupled lines. Therefore, LTCC broadside couplers that have parallel coupled lines on different layers are required for the tight broadside coupler. Hybrid couplers of the equal-division (3 dB) type can be composed of lumped elements or coupled transmission lines. The coupled-line type is generally applied to the hybrid couplers, because its return loss and directivity exhibit more wideband than those of the hybrid coupler with lumped elements such as inductor and capacitor [1]. However, a general coupler with coupled lines is requested to have improved performances of return loss and directivity, because its performances get worse in the high frequency band [2][3][4][5]. To resolve the problem of poor directivity, compensating technique by the use of shunt capacitor to ground was reported [4]. And conductor-backed coplanar structure generates a compensation for both the tightly and weakly coupled couplers [6]. However, design technologies with simple configuration are required to implement the couplers with high performances, because of the design complexity of conventional compensation technologies.In this work, we propose the compensation technique of LTCC broadside coupler. For tight coupling the characteristic impedance of the coupled-line is inherently high. So addition of branch lines at each port around the edge of the coupled-line reduces the characteristic impedance, resulting in better matching without any degradation of other parameters. EQUAL-DIVISION BROADSIDE COUPLER DESIGNA six-layered LTCC substrate made of Ferro A6 material was used for the coupler design. Figure 1 shows the conventional (a) and compensated (b) equal-division broadside couplers which are electrically asymmetric. The first input/output line between the input port (P1) and the through port (P2) was patterned on the top (sixth) layer. The second input/output line between the coupled port (P3) and the isolated port (P4) was patterned on the fifth layer and connected to the top layer by means of via-hole connection.The broadside coupler was simulated and optimized by using commercial software based on electromagnetic theory. Because of design constraint...

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“…Recently, the advances in modern wireless system require the multi-band operation capability and the conventional single-frequency microwave circuit components are evolving with the dualor the multi-band functionality. In the case of branch-line couplers, several dual-band schemes are proposed in the literature [2][3][4][5]. These include the use of left-handed transmission lines [2], crosscoupled branch-line structure [3], and the use of stub lines at the input ports [4] or at the center of the branches [5].…”

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confidence: 99%

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Dual‐band branch‐line coupler with two center‐tapped stubs

Kim

Lee

Park

2008

Micro & Optical Tech Letters

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Figure 5 shows the measured responses of the conventional and compensated couplers. The coupling of both couplers shows 3.3 dB at the center frequency. The measured return loss with the compensated broadside coupler exhibits an increase of 6.1 dB (from 17.2 to 23.3 dB) at 3.5 GHz. And the measured isolation shows an enhancement by 4.0 dB (from 18.3 to 22.3 dB) with the compensated design. Further improvement of return loss and isolation seems to be possible with more optimized design parameters. CONCLUSIONPerformance enhancement technique of the broadside coupler for the tight coupling has been realized with the LTCC technologies. Compensation approach by adding branch lines operates very well at C-band, resulting in 4.0 dB improvement of the isolation. The proposed compensation technique can be applicable at high frequency because the parasitic effects of branch lines are less than that of lumped elements. Recently, the advances in modern wireless system require the multi-band operation capability and the conventional single-frequency microwave circuit components are evolving with the dualor the multi-band functionality. In the case of branch-line couplers, several dual-band schemes are proposed in the literature [2][3][4][5]. These include the use of left-handed transmission lines [2], crosscoupled branch-line structure [3], and the use of stub lines at the input ports [4] or at the center of the branches [5]. DUAL-BAND BRANCH-LINE COUPLER WITH TWO CENTER-TAPPED STUBSThis letter proposes a new scheme for the dual-band operation of the branch-line coupler. The proposed structure is based on the use of center-tapped stub lines at one pair of branches of the conventional branch-line coupler. Although the existing stub-based dual-band schemes require four stubs in total for every ports [4] or branches [5] of the coupler, the proposed method requires only two stubs for two of the four branches of the coupler. The circuit complexity can be reduced accordingly and the structural change from the conventional branch-line coupler is minimized. As a matter of fact, the proposed structure reduces to the conventional branch line coupler for the specific band-ratio of 1-3.The proposed coupler structure is analyzed in detail using the scattering parameter formulation, and the exact design formulas are derived for the dual-band operation of the coupler. The validity of the proposed method is confirmed through the design, simulation and the measurement of a prototype dual-band coupler. Figure 1 shows the schematic representation of the proposed branch-line coupler for dual-band operation. For simplicity, only the open stub case is presented in the figure and will be analyzed in detail. The shorted stub case can be treated similarly, and the results will be presented at the end of this section. ANALYSIS AND DESIGNThe overall structure of the proposed coupler is quite similar to that of the conventional branch-line coupler except for two centertapped stub lines z 3 at two vertical branches of the coupler. The use of stub li...

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Theoretical and experimental investigations of a bilevel 'Lange' coupler

Cited by 7 publications

References 6 publications

Quasi-ideal multilayer two- and three-strip directional couplers for monolithic and hybrid MICs

Quasi-ideal multilayer two- and three-strip directional couplers for monolithic and hybrid MICs

Compensated LTCC broadside coupler design with branch lines

Dual‐band branch‐line coupler with two center‐tapped stubs

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