A Survey of Differential-Fed Microstrip Bandpass Filters: Recent Techniques and Challenges

Differentially driven devices represent a highly promising research field for radio frequency (RF), microwave (MW), and millimeter-wave (mmWave) designers and engineers. Designs employing differential signals are essential elements in low-noise fourth-generation (4G) and fifth-generation (5G) communications. Apart from the conventional planar MW components, differential–fed balanced microstrip filters, as promising alternatives, have several advantages, including high common-mode rejection, low unwanted radiation levels, high noise immunity, and wideband harmonic suppression. In this paper, a comprehensive and in-depth review of the existing research on differential-fed microstrip filter designs are presented and discussed with a focus on recent advances in this research and the challenges facing the researchers. A comparison between different design techniques is presented and discussed in detail to provide the researchers with the advantages and disadvantages of each technique that could be of interest to a specific application. Challenges and future developments of balanced microstrip bandpass filters (BPFs) are also presented in this paper. Balanced filters surveyed include recent single-, dual-, tri-, and wide-band BPFs, which employ different design techniques and accomplish different performances for current and future wireless applications

Design, Modeling and Numerical Analysis of Microwave and Optical Devices: The Multi-band Patch Antenna, Ultra Wideband Ring Filter and Plasmonic Waveguide Coupler

In this dissertation, three devices are studied and devised for the applications in microwave and optical communication: (1) Multiband Patch Antenna, (2) Ultra-Wideband Band Pass Ring Filter and (3) Plasmonic Waveguide Coupler with High Coupling Efficiency. First, the idea of a simple frequency reconfigurable patch antenna that operates at multiband from 2 GHz to 4.5 GHz is presented; by changing the position of the microstrip connecting elements on the antenna patches, the operating frequency will shift with fixed radiation patterns, which can be utilized in MIMO (Multiple IN Multiple Out) wireless data transmission. Next, a compact ultra-wideband (UWB) single-ring bandpass filter of 8GHz bandwidth with sideband and harmonics suppression achieved by forced boundary condition and step impedance filter is proposed. This approach provides a simple way for the design of ultra-wideband filters. Based on the transmission spectrum, it is known that the group delay variation in the pass-band is smaller than 0.3 ns, which indicates the proposed structure is very suitable for real applications. Finally, a short partially corrugated tapered waveguide for silicon-based micro-slab waveguide to plasmonic nano-gap waveguide mode conversion at the optical communication frequency is investigated. The structure is designed to achieve mode matching between the silicon slabs and plasmonic waveguides. High coupling efficiencies up to 87%~98% are demonstrated numerically. The results show that the corrugated structure will be helpful for realizing full on-chip silicon plasmonic devices

Horn Antennas and Dual-Polarized Circuits in Substrate Integrated Waveguide (SIW) Technology

The Substrate Integrated Waveguide (SIW) technology is a very promising candidate to provide widespread commercial solutions for modern communications systems. Its main advantage is the possibility to integrate passive/active components and antennas in the same substrate by using standard manufacturing processes, such as the Printed Circuits Board (PCB) processing technique. Nevertheless, the production of low-cost SIW devices is inherently linked to commercially available substrates and fabrication methods. In particular, these constraints usually limit (a) the frequency range of operation of certain SIW antennas and (b) the possibility of creating multimode structures dealing with orthogonal polarizations. The motivation of this PhD thesis is to overcome these two limitations by proposing innovative SIW components based on PCBs in order to favour the compatibility with existing systems and to lower their cost. Hence, the usage of the SIW technology would be extended towards new applications and scenarios. One type of antenna strongly affected by the limitation (a) is the H-plane SIW horn antenna. While standard horns are employed in many applications and in a wide range of frequencies, their counterparts in SIW technology are restricted to the Ka-band and above. At lower frequencies, commercial substrates are electrically thin and the performances of these end-fire antennas severely diminish. To solve this problem, a novel low-profile SIW horn antenna has been designed to be used at the Ku-band and below, while offering wideband characteristics. In addition, the horn shape has been further optimized to reduce the antenna footprint for a given directivity. In order to overcome the limitation (b), a substrate integrated guide able to simultaneously carry orthogonally polarized modes has been developed: the so called Extended Substrate Integrated Waveguide (ESIW). An ESIW dual-polarized system composed of an Orthomode Transducer (OMT) feeding a dual-polarized horn antenna has been designed and experimentally verified. The overall combination of concepts and ideas proposed in this thesis opens the door towards new SIW components that can increase the capacity, robustness and compactness ofmodern communication systems

Passive Planar Microwave Devices

The aim of this book is to highlight some recent advances in microwave planar devices. The development of planar technologies still generates great interest because of their many applications in fields as diverse as wireless communications, medical instrumentation, remote sensing, etc. In this book, particular interest has been focused on an electronically controllable phase shifter, wireless sensing, a multiband textile antenna, a MIMO antenna in microstrip technology, a miniaturized spoof plasmonic antipodal Vivaldi antenna, a dual-band balanced bandpass filter, glide-symmetric structures, a transparent multiband antenna for vehicle communications, a multilayer bandpass filter with high selectivity, microwave planar cutoff probes, and a wideband transition from microstrip to ridge empty substrate integrated waveguide

Перелаштовувані резонансні елементи на основі копланарних ліній передачі

Дисертаційна робота присвячена дослідженню методу мікромеханічного перелаштування частотних характеристик резонансних елементів на основі копланарних та щілинних ліній, що базується на зміні розподілу електромагнітного поля в лінії внаслідок вертикального переміщення складових частин лінії. Необхідні переміщення складають десятки мікрометрів та дозволяють досягти до 60% і більше діапазону перелаштування ефективної діелектричної проникності. Запропоновано методи розрахунку ефективної діелектричної проникності, втрат електромагнітної енергії та характеристичного опору копланарних та щілинних ліній, які не мають обмеження щодо геометричної форми та електрофізичних параметрів ліній. Встановлено закономірності впливу геометричних та електрофізичних параметрів ліній на зміну діапазону перелаштування та чутливості зміни ефективної діелектричної проникності копланарних та щілинних лінії до переміщень, які дозволяють оптимізувати проектування пристроїв на їх основі. Показано, що запропонований метод перелаштування не вносить додаткових втрат. Представлено структури шлейфових резонаторів на основі щілинних та копланарних ліній, які включено в копланарну лінію передачі, з можливістю мікромеханічного перелаштування зі зміною резонансної частоти до 80%. На основі теорії кіл з розподіленими параметрами запропоновано схемні моделі резонаторів, які дозволяють значно прискорити розрахунки їх частотних характеристик