Coupling Matrix Synthesis and Design of a Chained-Function Waveguide Filter

Lim, Yuan Ping; Toh, Yew Leong; Cheab, Sovuthy; Lucyszyn, S.; Wong, Peng Wen

doi:10.23919/apmc.2018.8617312

Cited by 6 publications

(15 citation statements)

References 8 publications

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“…Next, a modern filter synthesis approach, i.e., the coupling matrix synthesis and matrix rotation technique is employed to model and reconfigure the lowpass prototype filter network. In [6][7][8][9], the stated coupling matrix synthesis and matrix rotation techniques can be used as an universal method in the design of high performance microwave filters. The coupling matrix synthesis and matrix rotation approach can be easily utilized once the characteristic polynomials of the filter have been identified.…”

Section: Scope Motivations and Aimsmentioning

confidence: 99%

“…The chained-function polynomial is used to synthesize the filter coupling matrix. The coupling matrix synthesis and similarity transformation technique (matrix rotation) [6][7][8][9] can be used to replace the classical ladder synthesis technique. This technique allows reconfiguration of the complex coupling matrix through a sequence of similarity transformations until a more convenient coupling arrangement or topology is obtained, which is physically practical for realization.…”

Section: Coupling Matrix Synthesismentioning

confidence: 99%

“…This technique allows reconfiguration of the complex coupling matrix through a sequence of similarity transformations until a more convenient coupling arrangement or topology is obtained, which is physically practical for realization. Following the procedure explained in [6][7][8][9]…”

Section: Coupling Matrix Synthesismentioning

confidence: 99%

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On the Design and Fabrication of Chained-Function Waveguide Filters With Reduced Fabrication Sensitivity Using CNC and DMLS

Lim¹,

Cheab²,

Soeung³

et al. 2020

PIER B

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In this paper, we present the design and fabrication of a novel class of emerging waveguide filters based on chained-functions at the millimeter-wave band. The derivation of chained-functions by chaining of prescribed generalized Chebyshev seed functions based on the partition theory is presented in details, and the implementation to waveguide technology is proposed and evaluated. The waveguide filter is fabricated through two different technologies, namely the Computer Numerical Control (CNC) milling technology and the Direct Metal Laser Sintering (DMLS) based additive manufacturing technology. The chained-function filters, which lie in between the Butterworth and Chebyshev filters, inherit the salient properties of both Butterworth and Chebyshev filters. Therefore, the chained-function waveguide filter exhibits filtering responses that have a superior rejection property and a lower loss with reduced sensitivity to fabrication tolerance than the standard Chebyshev waveguide filter. The efficiency of the proposed waveguide filter is confirmed both theoretically and empirically, using the CNC and DMLS processes. The issues of a higher manufacturing tolerance and apparent surface roughness associated with the DMLS method are found to be electrically insignificant when the chained-function concept is adopted in waveguide filter design. In general, the measured results of all the realized waveguide filters agree well to those of the simulation models. These results positively demonstrate that the chainedfunction concept has robust properties for rapid, high-performance, low-cost, and sustainable filter design and implementation, particularly for higher millimeter-wave frequency bands and for narrowband applications.

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Section: Scope Motivations and Aimsmentioning

confidence: 99%

Section: Coupling Matrix Synthesismentioning

confidence: 99%

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On the Design and Fabrication of Chained-Function Waveguide Filters With Reduced Fabrication Sensitivity Using CNC and DMLS

Lim¹,

Cheab²,

Soeung³

et al. 2020

PIER B

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“…The formulation of chained-elliptic functions follows the same transfer function approximation for classical filters [5][6][7]. The general representation of the squared magnitude response is in the following form:…”

Section: Polynomial Generationmentioning

confidence: 99%

“…In addition, a high sensitivity filter results in wide fluctuations of the filter response during the tuning process, and thus, a substantial amount of time will be consumed to obtain an accurate filter response. The chained-function filters introduced in [1][2][3][4][5][6] have reduced sensitivity to the manufacturing tolerance. However, the chaining process will reduce the selectivity and close-to-band rejection of the filter [1], resulting in the need for higher order filters to compensate for the reduction in selectivity and rejection properties.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Chained-Elliptic Function Waveguide Bandpass Filter With High Rejection

Ng¹,

Cheab²,

Wong³

et al. 2020

PIER C

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This paper describes the synthesis of a bandpass filter to achieve high selectivity and rejection properties using a new class of filter functions called chained-elliptic function filters. Chainedelliptic filters have higher selectivity than Chebyshev function filters and have the property of sensitivity to manufacturing tolerance reduction in chained-function filters. The proposed design has high selectivity and reduced sensitivity, enabling easier and faster filter fabrication. The characteristic polynomials of chained-elliptic function filters are derived (through chaining elliptic filtering function) and extracted to form a coupling matrix of the bandpass filter. The novel transfer polynomials are given in detail, and a thorough investigation of the filter characteristics is performed. A theoretical comparison with Chebyshev and elliptic filters of the same order is performed to ascertain the demonstrated advantages of this proposed filter class. A high frequency narrow-band fourth-order chained-elliptic function waveguide filter centred at 28 GHz with a fractional bandwidth of 1.61% is fabricated to validate the proposed design concept. A good match among the measured, simulated, and ideal filter responses is shown where the overall responses between measurement and simulation have a difference of approximately 2% which is within the acceptable limit. The chained-elliptic function concept will be useful in designing low-cost high-performance microwave filters with various fabrication technologies for millimetre-wave applications.

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A New Class of Dual-Band Waveguide Filters Based on Chebyshev Polynomials of the Second Kind

et al. 2020

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This paper presents for the first time a method of mathematical synthesis involving chaining of Chebyshev polynomials of the second kind for the application of a dual-band waveguide filter. This method takes advantage of second kind Chebyshev polynomials that have high out-of-band rejection, and overcomes unequal-ripple properties. It is applicable to high filter orders greater than five, and will always possess symmetrical dual-band filter properties. This proposed approach is able to achieve an optimum and constant ripple, the flexibility of return loss, and high adjacent band's rejection. The design method is based on suitably defined transmission zeros at the centred frequency to the chained Chebyshev of the second kind. A sixth-order waveguide filter based on a prescribed return loss of 15 dB centred at a frequency of 28 GHz, with a fractional bandwidth of 1% in each passband, has been implemented and fabricated. The measured results show that the return loss, total bandwidth, and the frequency shift are 12 dB, 860 MHz, and 0.24%, respectively. The measured and ideal responses of the waveguide model are in a good agreement. INDEX TERMS Narrowband, second kind Chebyshev, symmetrical dual-bandpass filters, transmission zeros, waveguide.

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Coupling Matrix Synthesis and Design of a Chained-Function Waveguide Filter

Cited by 6 publications

References 8 publications

On the Design and Fabrication of Chained-Function Waveguide Filters With Reduced Fabrication Sensitivity Using CNC and DMLS

On the Design and Fabrication of Chained-Function Waveguide Filters With Reduced Fabrication Sensitivity Using CNC and DMLS

Synthesis of Chained-Elliptic Function Waveguide Bandpass Filter With High Rejection

A New Class of Dual-Band Waveguide Filters Based on Chebyshev Polynomials of the Second Kind

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