This paper introduces some generalized fundamentals for fractional-order RL
 β
 C
 α
 circuits as well as a gradient-based optimization technique in the frequency domain. One of the main advantages of the fractional-order design is that it increases the flexibility and degrees of freedom by means of the fractional parameters, which provide new fundamentals and can be used for better interpretation or best fit matching with experimental results. An analysis of the real and imaginary components, the magnitude and phase responses, and the sensitivity must be performed to obtain an optimal design. Also new fundamentals, which do not exist in conventional RLC circuits, are introduced. Using the gradient-based optimization technique with the extra degrees of freedom, several inverse problems in filter design are introduced. The concepts introduced in this paper have been verified by analytical, numerical, and PSpice simulations with different examples, showing a perfect matching.

Optimization of Fractional-Order RLC Filters

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Evanescent-Mode Substrate Integrated Waveguide (SIW) Filters Implemented with Complementary Split Ring Resonators

A dual-polarized system fully implemented in substrate integrated technology is presented. It comprises an orthomode transducer (OMT) with planar excitation schemes for both orthogonal TE10- and TE01-modes and a dual-polarized horn antenna. The whole structure requires only two layers of substrate, and it is based on the extended substrate integrated waveguide (ESIW), which allows the propagation of TEm0- and TE0n-modes. A compact OMT design is proposed along with a procedure to optimize it. The matching and radiation characteristics of a dual-polarized horn antenna fed with this OMT are also studied. The complete structure was manufactured exhibiting an 8.6% bandwidth (13.9-15.15 GHz) where both modes are well matched ( 28 dB). The horn radiation patterns within the frequency range of operation are also similar for both polarizations. The proposed design demonstrates the feasibility of dual-polarized substrate integrated circuits (SICs). This opens the door to new substrate integrated devices as well as to the use of SICs in applications requiring polarization diversity at end-fire. All together, this combined design becomes a promising approach to tackle the increasing demand for capacity in modern communication systems.

Orthomode Transducer and Dual-Polarized Horn Antenna in Substrate Integrated Technology

Package-integrated and ultra-thin low-pass filter (LPF) and bandpass filter (BPF) with footprint smaller than $0.5\lambda _{0}\times 0.5\lambda _{0}\times 0.025\lambda _{0}$ at the operating frequencies of 28- and 39-GHz bands are presented for 5G and mm-wave small-cell application. Such package integration of 5G filters with ultrashort 3-D interconnects allows for low interconnect losses that are similar to that of on-chip filters, but low component insertion loss of off-chip discrete filters. These thin-film filters exhibit a cross-sectional height of $188.5~\mu \text{m}$ and can be utilized either as embedded components or integrated passive devices in module packages. Three topologies of LPF and BPF in total are modeled, designed, and fabricated on precision thin-film buildup layers on glass substrate as a core. Large-area panel-compatible semiadditive patterning (SAP) process is utilized to form high-precision topologies to aid the low-cost fabrication of ultraminiaturized filters. SAP also enables the realization of ultra-thin traces to precisely model high-impedance inductive lines compared to conventional subtractive etching and printing techniques. This results in filters with low insertion loss, low VSWR, and high selectivity. The simulated and measured results of filters show an excellent correlation.

First Demonstration of Compact, Ultra-Thin Low-Pass and Bandpass Filters for 5G Small-Cell Applications

Two extended doublet bandpass fllters with compact size and good spurious suppression characteristic are proposed. One is built up by a dual-mode microstrip resonator with a full-mode substrate integrated cavity, while the other is composed of a microstrip resonator and a half-mode cavity. The relationship between the location of their transmission zeros and the impedance ratio of the microstrip resonator is analyzed theoretically. Our proposed fllters only occupy the areas of 0:69‚ 2 ="r and 0:51‚ 2 ="r, and they also have wide upper stopband. The predicted performances are demonstrated by the reasonable agreement obtained between their simulated and measured S-parameters.

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Extended Doublet Bandpass Filters Implemented with Microstrip Resonator and Full-/Half-Mode Substrate Integrated Cavities

This paper presents a scheme for designing band pass filters based on the high-mode of SIW cavity Compared with the dominant mode SIW cavity filters, the SIW cavity filters resonated on the high-mode can work on the higher frequency with the same size This property can be used to implement a higher frequency device with normal PCB process The response of dominant mode is suppressed by the cutoff frequency of SIW, the desired higher order modes are excited with special design, and the nearby spurious band is suppressed by adding a metal post in the center of the cavity

Design of A Ka-Band Bandpass Filter Based on High Order Mode SIW Resonator

A broadband planar orthomode transducer (OMT) is implemented using substrate integrated waveguide (SIW). A square waveguide is mounted on the substrate where four SIW arms are used to separate orthogonally polarized signals. Four rectangular ridges are inserted into the square waveguide to match the impedance between the square waveguide and SIW. A SIW-to-microstrip line transition and a coaxial-to-square waveguide adaptor are designed for the measurement of the proposed OMT. The designed SIW-OMT operates over the C band covering from 3.4 GHz to 4.2 GHz, whose bandwidth is more than 25%, and measured results validate our design, concept and procedures.

Broadband Substrate Integrated Waveguide Orthomode Transducers

A compact dual-band ortho-mode transducer is presented in this paper. Two orthogonally polarized signals received by a square waveguide are separated into two orthogonal channels at 10.7{ 12.75GHz and 10.3{11.9GHz, respectively, while a single-polarized signal is transmitted at 14{14.5GHz. To obtain good isolation between the transmit (Tx) and receive (Rx) channels of the same polarization with a compact size, an irregularly shaped diaphragm is proposed as a compact dual-function resonator, which has one transmission zero at the Tx band and one pole at the Rx band. The designed OMT is fabricated and measured in a back-to-back conflguration. Measured results agree very well with simulated ones and the isolation improvement by the diaphragm is about 15dB, which verifles our design.

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Dual-Band Ortho-Mode Transducer with Irregularly Shaped Diaphragm

A broadband planar orthomode transducer has been implemented using substrate integrated waveguide and its design process has been presented. A simple quadruple-ridge transition has been used to achieve a good impedance match between a square waveguide and SIW over a wide frequency range. Compared to the waveguide OMT, the SIW-OMT is very low in profile, easy to fabricate, and can be readily integrated with other planar circuits including the antenna feed.

Design of broadband planar orthomode transducers using substrate integrated waveguide

In this paper, closed-form expressions for the equivalent circuit model of square-waveguide T-junctions are presented. The square-waveguide T-junction is first modeled as a generalized admittance matrix and then reduced to a general five-port network. It is theoretically seen that the general five-port network can be simplified as a combination of a two-port subnetwork and a three-port subnetwork through the mode-matching analysis. Accurate closed-form expressions are derived with proper approximations to calculated the admittance parameters of these two subnetworks. A short-circuited branch ortho-mode transducer is then designed in a circuit simulator using the proposed equivalent circuit model. Measured results exhibit an excellent agreement with those from circuit simulation.

Yun Tao

Papers

Design of A Ka-Band Bandpass Filter Based on High Order Mode SIW Resonator

Broadband Substrate Integrated Waveguide Orthomode Transducers

Dual-Band Ortho-Mode Transducer with Irregularly Shaped Diaphragm

Design of broadband planar orthomode transducers using substrate integrated waveguide

Closed-Form Expressions for the Equivalent Circuit Model of Square-Waveguide T-Junctions and Its Application in Ortho-Mode Transducer Design