Design and Synthesis of Dual Polarized Millimetre Wave Array Antennas for Advanced Wireless Communications

The millimetre-wave (mmWave) antenna arrays in traditional designs are usually very complicated, bulky and expensive. They suffer compromised radiation efficiency because of high insertion loss caused by the intricate feed networks. In addition, the cross polarization level is degraded, especially for the multibeam antenna arrays. To reduce the complexity and improve the electric characteristics, it is significant to develop mmWave antenna arrays with multi-functionality such as dual polarization, cross polarization suppression, beam switching and power splitting/combining, etc.In this thesis, four designs of sub-mmWave and mmWave dual polarized antenna arrays with low complexity, compact size and good electrical performance are proposed. Firstly, a dual slant polarized cavity-backed slot-coupled patch antenna arrays with modified feed networks is developed. This antenna array features high XPD, simple structure and low profile. Then, a dual polarized 2D multibeam shorted-patch antenna array with high XPD when beams scan to the maximum pointing angles is developed. Differential feed technique is used to design the multibeam antenna array for the first time. The third design is a dual polarized frequency-scanning cross slot antenna array realized on a single laminate. To enable high port isolation and excitation from orthogonal directions, a SIW crossover is proposed. This antenna array shows advantages in terms of low complexity, high XPD, high aperture efficiency and wide beam scanning range. A dual polarized slot-coupled patch antenna array differentially fed by an orthomode transducer is developed in the last design. The feed networks are taken into consideration of designing the subarray antenna. The via-loaded crossover is used to enable structure simplification and triple resonance is excited to improve operation bandwidth. This antenna array features low complexity, high XPD, high radiation efficiency, high gain and high integration.In this thesis, the design methods and synthesis procedures are detailed in order todeliver a comprehensive guide of designing the dual polarized antenna arrays. The design concept and outcomes of these antenna arrays are evaluated in the high frequency fullwave solver. All of the antenna arrays are prototyped and measured for validating the simulations. The measurements are in good agreement with the simulations, evidencing that the proposed antenna arrays have advantages in terms of high XPD, high aperture efficiency, high port isolation, low complexity and low profile. The design concepts depicted in this thesis and the developed antenna arrays could find potential applications in mobile communication systems and satellite communication systems

Stability bound analysis of singularly perturbed systems with time-delay

This paper considers the stability bound problem of singularly perturbed systems with time-delay. Some stability criteria are derived by constructing appropriate Lyapunov-Krasovskii functionals. The proposed criteria are less conservative than the existing ones. Two numerical examples are given to illustrate the advantages and effectiveness of the proposed methods

A Compact Broadband 16×16 Butler Matrix for Multibeam Antenna Array Applications

This paper presents a compact 16×16 Butler Matrix operated from 9 GHz - 11 GHz. Compared with the traditional structure, the presented network is much simpler and can be easily designed. The number of needed components in the design is only sixty, where the number of crossovers is four. In addition, the designed network can be fully realized in a single layer laminate with the size of 165 mm × 165 mm (5.5λ 0 × 5.5λ 0 ). It is shown that the maximum simulated output phase error at 10 GHz is only ±8° and the transmission coefficients are in the range of -14.5 ± 1.5dB over the bandwidth. The measured and simulated results agree well. The designed network can be a potential candidate for the one or two dimensional multibeam array antennas

Improving the Performance of PCA-Based Chiller Sensor Fault Detection by Sensitivity Analysis for the Training Data Set

An improved approach of fault detection for chiller sensors is presented based on the sensitivity analysis for the original data set used to train the Principal Component Analysis (PCA) model. Sensor faults are inevitable due to the aging, environment, location and so on. Meanwhile, because of the wide range of operational conditions, the fault of a certain sensor is very difficult to be directly detected by its own historical data. PCA is a multivariate data-based statistical analysis method and it is very useful for the sensor fault detection in HVAC&R. The undetectable zone of a certain sensor by Q-statistic is derived from the definition of Q-statistic which is usually employed as a boundary to detect the sensor fault situation. Due to the similar style between Q-statistic and Hawkins’ TH2, the undetectable zone by Hawkins’ TH2 is also obtained. Undetectable zone is a predictive index to indicate the detectability of different sensors by different statistics. Since undetectable zone is the character of the original training data set, it can indicate the quality for the selected training data. One field data set is employed to validate the presented approach. Results show that the undetectable zone of a certain sensor by Q-statistic is quite different from that by Hawkins’ TH2. Therefore, the undetectable zone can be used to improving the performance of PCA-based chiller sensor fault detection by choosing different fault detection statistics with less undetectable zone for different sensor

Biochemical Engineering of Surface α2–8 Polysialic Acid for Immunotargeting Tumor Cells

To target tumor cells for immunotherapy, we evaluated the feasibility of altering the epitopes on the surface polysialic acid of tumor cells. A precursor (N-propionylmannosamine), when incubated with leukemic cells, RBL-2H3 and RMA, resulted in substitution of the N-acetyl groups of surface alpha2-8 polysialic acid with N-propionyl groups. Expression of the altered alpha2-8 N-propionylpolysialic acid on the surface of tumor cells induced their susceptibility to cell death mediated by monoclonal antibody 13D9 (mAb 13D9), which specifically recognizes alpha2-8 N-propionylated polysialic acid. The expression of alpha2-8 N-propionylated polysialic acid and the lysis of tumor cells by antibody-dependent cytotoxicity depended on the time and dose of incorporation of N-propionylated mannosamine. In vivo, mAb 13D9 effectively controlled metastasis of leukemic cells RMA when mice were administered the precursor N-propionylated mannosamine

Millimetre-Wave Dual-Polarized Differentially-Fed 2D Multibeam Patch Antenna Array

In this paper, a novel millimetre-wave dual-polarized 2D multibeam antenna array incorporating differentially-fed antenna elements is proposed to achieve high cross-polarization discrimination (XPD) when the beams scan to the maximal pointing angles. The antenna element is composed of a SIW cavity with four shorted patches placed inside, and it is differentially excited for dual-polarization by a pair of feeding strips and transverse slots beneath the patches. Differential excitation is realized by a power divider designed on two laminate layers. Two Butler Matrices placed perpendicularly with each other in different laminates are employed to generate four tilted beams with dual-polarization. A 2 × 2 dual-polarized 2D multibeam antenna array working at 28 GHz is designed, fabricated, and measured. The operation bandwidth of the antenna is 26.8 GHz – 29.2 GHz. The improvement in the XPD is experimentally demonstrated by far-field measurement. When the beams scan to 30◦ off the boresight, the measured XPDs are 28 dB at the centre frequency and higher than 25 dB over the operation bandwidth, which confirms that the cross-polarized radiation in the 2D multibeam antenna array is suppressed by using the differential-feeding technique. The measured gain is in the range from 7.6 dBi to 10.5 dBi

A Dual-Polarized Planar Antenna Array Differentially-Fed by Orthomode Transducer

This paper presents a new design of a differentially-fed substrate integrated planar antenna array with dual-polarization. Compared with the traditional dual-polarized antenna arrays, the proposed array antenna has the advantages of simple configuration, high cross-polarization discrimination (XPD) and high gain. 2×2-element subarray design with a vialoaded crossover structure is used, which reduces the complexity of the array antenna. The operation bandwidth is improved by generating three resonances in the subarray. One 8×8 antenna array is designed, prototyped and tested to exemplify its potential applications in large dual-polarized antenna arrays. A planar orthomode transducer is used to achieve differential excitation for the antenna array. The measured results show that the proposed antenna array has an impedance bandwidth of 19.2–20.7 GHz for |S11| < −10 dB and port isolation higher than 20 dB. The array antenna exhibits a high XPD of 43 dB and a flat gain about 22.2 dBi within the bandwidth

A Low Complexity 16 X 16 Butler Matrix Design Using Eight-Port Hybrids

Beamforming networks such as Butler Matrices are important for multibeam array antenna applications. The challenge for Butler Matrix design is that their complexity increases with the number of ports. In this paper, a novel approach of designing a 16 X 16 Butler Matrix with significant structure simplification is presented. The eight-port hybrids with no crossovers are used to simplify the network. To ensure the network has the same magnitude and phase responses as the standard one, the location and phase shifting value of each fixed phase shifter are derived from the $S$ -matrix of each hybrid. A $16\times 16$ Butler Matrix network operating from 9 GHz–11 GHz is designed to validate this concept. The compensated microstrip 3-dB/90° directional coupler, the phase shifter with a shunt open-and-short stub and the crossover with a resonating patch are used to reduce the transmission loss and enable broadband operation