Chained-Function Waveguide Filter for 5G and Beyond

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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“…When |FF(ω)| is at maximum, e.g. |FF (ω)| = 1, the transfer function for the chained function can be deduced by multiplying (14) with FF C (ω):…”

Section: General Expression For the Chained Function Polynomials Omentioning

confidence: 99%

“…13. The sensitivity analysis is conducted by applying a ±10% tolerance to their coupling matrices and compared their filter performances to those of the ideal models [14], [15]. It should be noted that [14] and [15] are only limited to single-band filter realisations.…”

Section: Sensitivity To Manufacturing Errorsmentioning

confidence: 99%

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

et al. 2020

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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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“…Designing Chebyshev filters has always been challenging [9]. The chained function on the other hand can be found to compromise between Butterworth and Chebyshev approximations [10], [11] because it could combine the advantages of both Butterworth functions (lower filter losses, lower sensitivity, and lower resonator unloaded-Q factor) and Chebyshev functions (i.e., higher out-of-band and higher selectivity rejection) [12]. The technique of chained transfer functions can reduce filter complexity, manufacturing tolerance, and, most importantly, post-manufacturing tuning processes [4], [13].…”

Section: Introductionmentioning

confidence: 99%

Design and Synthesis of Parallel-Connected Dielectric Filter Using Chain-Function Polynomial

Chinda¹,

Cheab²,

Soeung³

2023

RADIOENGINEERING

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Design and synthesis of parallel connected dielectric filters using chained function polynomials are presented in this paper. This filter will offer reduced sensitivity to fabrication tolerance while preserving its return loss response within the desired bandwidth in comparison to traditional Chebyshev filters. A novel transfer function FN according to chained is derived for fourth and sixth-order filters and the synthesis technique is presented. To demonstrate the feasibility of this approach, the circuit simulation based on parallel connected topology is carried out in ADS while the design and simulation of the fourth-order filter in dielectric technology in HFSS. Considerable sensitivity analysis is conducted to prove a better fabrication tolerance of the filter. In terms of implementation, this design technique will serve as a very useful mathematical tool for any filter design engineer.

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Chained-Function Waveguide Filter for 5G and Beyond

Cited by 6 publications

References 10 publications

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

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

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

Design and Synthesis of Parallel-Connected Dielectric Filter Using Chain-Function Polynomial

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