Miniaturization Trends in Substrate Integrated Waveguide (SIW) Filters: A Review

This review provides an overview of the technological advancements and miniaturization trends in Substrate Integrated Waveguide (SIW) filters. SIW is an emerging planar waveguide structure for the transmission of electromagnetic (EM) waves. SIW structure consists of two parallel copper plates which are connected by a series of vias or continuous perfect electric conductor (PEC) channels. SIW is a suitable choice for designing and developing the microwave and millimetre-wave (mm-Wave) radio frequency (RF) components: because it has compact dimensions, low insertion loss, high-quality factor (QF), and can easily integrate with planar RF components. SIW technology enjoys the advantages of the classical bulky waveguides in a planar structure; thus is a promising choice for microwave and mm-Wave RF components

Recent Trends on Dual- and Triple-Band Microwave Filters for Wireless Communications

In the past few years, several designs of dual- and triple-band microwave filters satisfying various objectives have been proposed for wireless communication. Several designs are new concepts, whereas others are inspired from previous works. The development trends of these designs can be reviewed from this compilation of studies. This paper begins with an explanation of dual- and triple-band microwave filters, followed by a discussion on several designs in terms of size, measurement, performance, and technology use. Among various designs, microstrip band-pass filters are extensively used because of their simple design procedures and because they can be integrated into circuits easily. Furthermore, most researchers use low frequencies in their designs because of the demands of current wireless applications. Finally, designs are proposed to produce compact microwave filters with good performance

Miniaturized Resonator and Bandpass Filter for Silicon-Based Monolithic Microwave and Millimeter-Wave Integrated Circuits

© 2018 IEEE. © 2018 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission.This paper introduces a unique approach for the implementation of a miniaturized on-chip resonator and its application for the first-order bandpass filter (BPF) design. This approach utilizes a combination of a broadside-coupling technique and a split-ring structure. To fully understand the principle behind it, simplified LC equivalent-circuit models are provided. By analyzing these models, guidelines for implementation of an ultra-compact resonator and a BPF are given. To further demonstrate the feasibility of using this approach in practice, both the implemented resonator and the filter are fabricated in a standard 0.13-μm (Bi)-CMOS technology. The measured results show that the resonator can generate a resonance at 66.75 GHz, while the BPF has a center frequency at 40 GHz and an insertion loss of 1.7 dB. The chip size of both the resonator and the BPF, excluding the pads, is only 0.012mm 2 (0.08 × 0.144 mm 2).Peer reviewe

Ultra-miniaturized and high-Q embedded loaded coaxial cavity resonators and filters

The rapid development in modern wireless communication systems and remote sensing and their applications towards portable and compact systems are inevitable. Microwave filters are critical components in the RF front-ends for band selection and unwanted signal rejection. These filters generally occupy a large area in the RF front-ends. In addition, RF filters’ in-band losses significantly impact the overall system performance, such as noise figure and dynamic range. Thus, compact and high-quality factor RF filters are greatly desirable. Embedded coaxial substrate integrated waveguide filters have shown great potential compared to competing technologies in terms of high-Q, compact size, planar form, and wide spurious free region. This dissertation develops the theory and design of ultra-miniaturized high-Q embedded loaded coaxial substrate integrated waveguide filters with potential application in modern communication systems. In this research, high-Q and compact embedded loaded coaxial substrate integrated waveguide (ELCSIW) resonators are designed and investigated. Integrating air-filled parallel plate capacitive loading into an embedded coaxial cavity enables the achievement of a highly miniaturized resonator with a 99 % miniaturization factor compared to the conventional substrate integrated waveguide resonator. In-depth analysis of the resonant frequency, miniaturization factor, and unloaded quality factor is presented. A second-order embedded loaded coaxial substrate integrated waveguide filter with a resonant frequency of 1.1 GHz is developed and implemented. The filter obtains a simulated insertion loss of 0.26 dB and a wide spurious free stopband up to seven times its resonant frequency. The overall ELCSIW filter size is 0.07λg × 0.26λg. The proposed ELCSIW filter demonstrates superiority in compactness, quality factor, and stopband rejection compared to other miniaturized counterparts. Moreover, the proposed ELCSIW filter showed a high power handling capability of 113 Watts through theoretical investigation. A mixed (electric and magnetic) inter-resonator coupling mechanism is developed and integrated into the ELCSIW filter to generate a transmission zero to improve the stopband rejection. The arbitrary location of the transmission zero is determined by the intensity of each coupling mechanism. Moreover, a novel post-fabrication frequency tuning mechanism for the embedded loaded coaxial substrate integrated waveguide filter is developed. The tuning mechanism is constructed of additional embedded capacitive loading strip lines that can be altered to compensate for fabrication tolerances. The circuit model and the working mechanism of the tuning circuit are explained and illustrated. The novel tuning method shows a capability of a post-fabrication tuning range of 10 % for the proposed ELCSIW filter. This research illustrates the feasibility of designing and integrating low-loss, compact, low-cost, and lightweight filters for future communications and radar systems

Dual-Band Bandpass Filter with Dumbbell Shaped Defective Ground Structure

A dumbbell shaped defective ground structure (DGS) is implemented to improve the performance of an existing dual-band bandpass filter topology. The filter design is based on parallel-coupled lines connected to matched transmission lines. Various positions and dimensions of dumbbell DGSs are implemented and their effects on the filter performance are investigated. It is found that the utilisation of dumbbell shaped DGSs in this topology improve the steepness of the responses for the first and second passbands with centre frequencies of 1.365 and 2.932 GHz respectively. The optimised dimensions of the DGS are 5 x 5 mm2 for both its rectangular slots connected by a 0.5 mm narrow slot width. The optimised positions of the DGSs are located at the centre and the edges of the parallel-coupled lines. The simulated and measured results of the filter are analysed and discussed in this paper

A Class of Compact Substrate Integrated Waveguide Filters

This thesis work explores the design of compact and high performance microwave filters using substrate integrated waveguide technology. A substrate integrated waveguide is aplanar version of a conventional waveguide, which is having features like planar circuit integrability, ease of fabrication, low-cost and high power handling. A class of Substrate Integrated Waveguide (SIW) and Half mode Substrate Integrated waveguide (HMSIW) bandpass filters are proposed in this context. Applications like satellite communication uses devices which can withstand high power. Therefore, SIW filters can be used for satellite applications in the microwave bands like Ku, X, C, S, and L etc.The main objective of this thesis is to design SIW bandpass filters using simple planar technology and low-cost substrates. To fulfill this, a class of compact and easily fabricable SIW bandpass filters are proposed for Ku-band (12 − 18GHz) and S-band (2 − 4GHz) applications. These filters are designed using simple electromagnetic band gap (EBG) structures and latest feeding techniques like tapered-via feeding. Filters are designed using low-cost and easily available substrate FR4 with the help of High frequency structural simulator (HFSS) V.14. The dimensions of the filters are optimized and simulation results are analyzed. The proposed Ku-band filter has proven to be compact since its footprint is 160mm2. The S-band filter has been fabricated using low-cost and easily available FR4 substrate. The measurement results are found to be good in agreement with the simulation results. Though the obtained results are similar to the other reported filters, there is a huge demand of compactness in this miniaturization era. Therefore, another well-established concept of Half-mode SIW (HMSIW) technology is used to further reduce the size of the designed filters. So a compact HMSIW bandpass filter is designed for the Ku-band applications which is almost half in size as compared to conventional SIW designs. The return loss is achieved as 45dB and insertion loss is 1.5dB in the passband of the filter, which is promising corresponding to the size. Another similar design is made for X-band (8 − 12GHz) applications using HMSIW technology. The overall footprint of the filter which shows its compactness; is 102mm 2 i.e. almost half the size of its equivalent SIW filter

Passband broadening ofsub-wavelength resonator-basedglide-symmetric SIW filters

Here, we discuss the virtues of glide symmetry for designing low-frequency band-pass periodic filters in substrate integrated waveguide (SIW) technology based on complementary split-ring resonators (CSRRs). Conventional (non-glide) versions of these filters have a narrow passband, due to the fact that this band is below the cutoff frequency of the background waveguide. When glide symmetry is added to the filter configuration, the low-frequency passband is significantly widened, as well as the first stopband. The dispersion properties of both conventional and glide-symmetric periodically loaded waveguides are analyzed and compared with commercial software and an equivalent circuit model. Finally, two prototypes of the proposed glide-symmetric structure have been designed and built, illustrating the potential of this technique to widen the passband and reduce insertion losses of conventional sub-wavelength CSRR-loaded SIW filters

Miniaturized High-Q Tunable RF Filters

This dissertation focuses on the investigation and development of novel efficient tuning techniques and the design of miniaturized high-Q tunable RF filters for high-performance reconfigurable systems and applications. First, a detailed survey of the available tuning concepts and state-of-art tunable filters is provided. Then, a novel so-called inset resonator configuration is presented for the applications of fixed and tunable coaxial filters. The design procedure of frequency tunable filters with constant absolute bandwidth (CABW) is described, and various tunable inset filters are implemented, offering many desirable merits, including the wide tuning range and stable high-Q with minimum variation. For wide octave frequency tuning ranges with CABW, a second novel concept is presented using so-called re-entrant caps tuners. Beside simplicity and compactness, this technique also features enhanced spurious performance and wider tuning capabilities than the conventional means. Also, in this dissertation, various miniaturized reconfigurable dual-band/dual-mode bandpass filters and diplexers are presented using compact dual-mode high-Q TM-mode dielectric resonators. Furthermore, a novel microfluidic-based ultra-wide frequency tuning technique for TM010-mode dielectric resonators and filters is introduced in this dissertation. In addition to the very wide tuning window, this mechanism has key advantages of low-cost, simplicity, and intrinsic switch-off. Lastly, the dissertation includes a novel bandwidth reconfiguration concept with multi-octave tuning using a single element for coaxial bandpass filters. This mechanism brings many features including the fast tuning, constant high-Q, intrinsic switch-off, and wide BW-reconfiguration

An Extremely Miniaturized Two-stage Bandpass

Bandpass filters are key components in RF/microwave communication systems. As the system goes smaller and lighter, size reduction becomes more and more important. In addition, impedance matching and high performance is also crucial to a communication system. Thus, a two-stage bandpass filter with both small size and automatically matching is more desirable. In this thesis, a novel miniaturized CMOS bandpass filter will be introduced. It is based on the structure of diagonally short-ended coupled line with loaded capacitors for size reduction and using multilayer conductors for high quality factor. In this structure, the ground plane is capsulated around the filter, which enables it avoid the coupling to other basic components in the transceiver system. In addition, as another major advantage, it was proven to have an impedance matching automatically. The greater difference between the simulation and measurement in CMOS fabrication is also analysed and it will be proven to be caused by transmission losses and quality factors in the lossy distributed inductor of shunt resonator. Design equations and method will be fully explained in this thesis. A lot of simulated results and measured results are also presented. The method of enhancing the performance of the bandpass filters and automatically impedance matching will be described. Four kinds of circuits which based on the MagnaChip 0.18μm process are fabricated. Many simulated and measured data are collected and provided here to show the advantages of the proposed bandpass filter.Contents Nomenclature List of Figures Abstract CHAPTER 1 Introduction 1.1 An introduction to the filters at present 1.2 Organization of the thesis CHAPTER 2 The Bandpass Filter Design Theory 2.1 Size reduction method 2.2 The two-stage filter 2.3 The inter-stage signal line enhancement method CHAPTER 3 The Simulation , fabrication and results analysis 3.1 The inter-stage signal line improvement 3.2 Simulation and fabrication 3.3 The quality factor effect on the resonance frequency shift CHAPTER 4 Conclusion References Acknowledgemen

A Recent Approach towards Fluidic Microstrip Devices and Gas Sensors: A Review

This paper aims to review some of the available tunable devices with emphasis on the techniques employed, fabrications, merits, and demerits of each technique. In the era of fluidic microstrip communication devices, versatility and stability have become key features of microfluidic devices. These fluidic devices allow advanced fabrication techniques such as 3D printing, spraying, or injecting the conductive fluid on the flexible/rigid substrate. Fluidic techniques are used either in the form of loading components, switching, or as the radiating/conducting path of a microwave component such as liquid metals. The major benefits and drawbacks of each technology are also emphasized. In this review, there is a brief discussion of the most widely used microfluidic materials, their novel fabrication/patterning methods