SERIES APERTURE COUPLED FED PHASED ARRAY ANTENNA

Phased arrays are employed in a wide range of civil and Military contexts, including RADAR, cellular communications, and satellite communications. However, modern phased-array antennas require complex design and bulky structure at high costs, hindering their implementation in many applications. The critical aspect of a phased array design lies in power splitting with a proper phase to each radiating element. Conventional power splitters such as quarter-wavelength or Wilkinson power splitters suffer problems associated with complex array network and high power dissipation. Furthermore, popular phase shifters such as MEMS switch, ferrite-based or PIN diode have drawbacks of low power-handling capability, expensive packaging, and difficult fabrication process. The presented work introduces an innovative approach to phased array antenna design, centered around a quadrature hybrid phase shifter and a novel feeding technique known as series aperture coupling. The essence of this design lies in its ability to harness electronic components that are not only cost-effective but also highly efficient, serving the same purpose as existing methods while significantly reducing overall expenses. Unlike conventional methods that rely on control mechanisms such as magnetic fields to alter the properties of specific materials like ferrites, thereby achieving phase shifting of the signal, this invention takes a different route. It leverages signal reflection through the utilization of variable capacitors to attain the same goal. This approach offers a more accessible and economical means of achieving the desired phase shifts in the signal. One of the key innovations lies in the implementation of a cascade phase shifter connection. This configuration proves instrumental in establishing a highly responsive phased array structure. By linking phase shifters in a cascade arrangement, it becomes possible to fine-tune the phase relationships of individual radiating elements, resulting in a highly adaptable and sensitive phased array. Furthermore, the series aperture coupled feeding method presents a unique advantage in terms of optimizing the available material space. This approach streamlines the design process, minimizing the need for external devices and bulky materials. The result is an antenna design that operates with enhanced efficiency and reduced interference from external components. Additionally, the use of power splitters based on quadrature hybrids between each 1-D subarray further streamlines the design and enhances the ease of expanding the array system. In summary, this work represents a significant departure from traditional phased array antenna design, offering a more cost-effective, versatile, and streamlined solution. By harnessing the capabilities of quadrature hybrid coupler, variable capacitors, and cascade phase shifter configurations, the proposed design holds the potential to advance the field of phased array antennas, making them more accessible and efficient for a range of applications

Integrated Antennas and Active Beamformers Technology for mm-Wave Phased-Array Systems

In this thesis, based on the indoor channel measurements and ray-tracing modeling for the indoor mm-wave wireless communications, the challenges of the design of the radio in this band is studied. Considering the recently developed standards such as IEEE 802.15.3c, ECMA and WiGig at 60 GHz, the link budget of the system design for different classes of operation is done and the requirement for the antenna and other RF sections are extracted. Based on radiation characteristics of mm-wave and the fundamental limits of low-cost Silicon technology, it is shown that phased-array is the ultimate solution for the radio and physical layer of the mobile millimeter wave multi-Gb/s wireless networks. Different phased-array configurations are studied and a low-cost single-receiver array architecture with RF phase-shifting is proposed. A systematic approach to the analysis of the overall noise-figure of the proposed architecture is presented and the component technical requirements are derived for the system level specifications. The proposed on-chip antennas and antenna-in-packages for various applications are designed and verified by the measurement results. The design of patch antennas on the low-cost RT/Duroid substrate and the slot antennas on the IPD technologies as well as the compact on-chip slot DRA antenna are explained in the antenna design section. The design of reflective-type phase shifters in CMOS and MEMS technologies is explained. Finally, the design details of two developed 60 GHz integrated phased-arrays in CMOS technology are discussed. Front-end circuit blocks such as LNA, continuous passive reflective-type phase shifters, power combiner and variable gain amplifiers are investigated, designed and developed for a 60 GHz phased-array radio in CMOS technology. In the first design, the two-element CMOS phased-array front-ends based on passive phase shifting architecture is proposed and developed. In the second phased-array, the recently developed on-chip dielectric resonator antenna in our group in lower frequency is scaled and integrated with the front-end

Automatic Tuning of Silicon Photonics Millimeter-Wave Transceivers Building Blocks

Today, continuously growing wireless traffic have guided the progress in the wireless communication systems. Now, evolution towards next generation (5G) wireless communication systems are actively researched to accommodate expanding future data traffic. As one of the most promising candidates, integrating photonic devices in to the existing wireless system is considered to improve the performance of the systems. Emerging silicon photonic integrated circuits lead this integration more practically, and open new possibilities to the future communication systems. In this dissertation, the development of the electrical wireless communication systems are briefly explained. Also, development of the microwave photonics and silicon photonics are described to understand the possibility of the hybrid SiP integrated wireless communication systems. A limitation of the current electrical wireless systems are addressed, and hybrid integrated mm-wave silicon photonic receiver, and silicon photonic beamforming transmitter are proposed and analyzed in system level. In the proposed mm-wave silicon photonic receiver has 4th order pole-zero silicon photonic filter in the system. Photonic devices are vulnerable to the process and temperature variations. It requires manual calibration, which is expensive, time consuming, and prone to human errors. Therefore, precise automatic calibration solution with modified silicon photonic filter structure is proposed and demonstrated. This dissertation demonstrates fully automatic tuning of silicon photonic all-pass filter (APF)-based pole/zero filters using a monitor-based tuning method that calibrates the initial response by controlling each pole and zero individually via micro-heaters. The proposed tuning approach calibrates severely degraded initial responses to the designed elliptic filter shapes and allows for automatic bandwidth and center frequency reconfiguration of these filters. This algorithm is demonstrated on 2nd- and 4th-order filters fabricated in a standard silicon photonics foundry process. After the initial calibration, only 300ms is required to reconfigure a filter to a different center frequency. Thermal crosstalk between the micro-heaters is investigated, with substrate thinning demonstrated to suppress this effect and reduce filter calibration to less than half of the original thick substrate times. This fully automatic tuning approach opens the possibility of employing silicon photonic filters in real communication systems. Also, in the proposed beamforming transmitter, true-time delay ring resonator based 1x4 beamforming network is imbedded. A proposed monitor-based tuning method compensates fabrication variations and thermal crosstalk by controlling micro-heaters individually using electrical monitors. The proposed tuning approach successfully demonstrated calibration of OBFN from severely degraded initial responses to well-defined group delay response required for the targeted radiating angle with a range of 60◦ (-30◦ to 30◦ ) in a linear beamforming antenna array. This algorithm is demonstrated on OBFN fabricated in a standard silicon photonics foundry process. The calibrated OBFN operates at 30GHz and provide 2GHz bandwidth. This fully automatic tuning approach opens the possibility of employing silicon OBFN in real wideband mm-wave wireless communication systems by providing robust operating solutions. All the proposed photonic circuits are implemented using the standard silicon photonic technologies, and resulted in several publications in IEEE/OSA Journals and Conferences

Design of Tunable Beamforming Networks Using Metallic Ridge Gap Waveguide Technology

Wireless communication is a leap of development in the history of humanity. For the past 100 years, a considerable effort has been spent to develop better standards, and technologies for a higher speed wireless communication with high system capacity for different applications. This requires the design of a high-frequency, point-to-multipoint antenna array system to achieve the mentioned goals. In addition, the reconfigurability of this antenna system is essential to change the system characteristics to achieve acceptable performance in different situations. The main goal of this thesis is to design a reconfigurable beamforming network to work on the Ka-band for waveguide applications. Among different beamforming networks in the literature, the Butler matrix is chosen due to its higher efficiency and the smaller number of components required than other beamforming networks. The Butler matrix is designed using a dual-plane topology to avoid using crossovers. Ridge gap waveguide technology is chosen among different transmission lines to implement the Butler matrix for several reasons: It does not need dielectrics to operate, so its power handling capacity is defined by the gap height, and it has no dielectric losses. Its zero-field region represents the operating principle for some tunable devices introduced here and its contactless nature, which eases the assembly of waveguide parts at the millimeter-wave frequencies. The reconfigurability of the Butler matrix is implemented such that beamwidth, maximum gain, and beam direction may be all tuned for optimum system performance. To that end, several components are designed to achieve the required target, and strict requirements are placed on several components to achieve an acceptable cascaded-system performance. These components include a ridge gap waveguide 90o-hybrid working over a more than 30% bandwidth, which can provide several coupling levels ranging from 3 dB to 33 dB and a return loss and isolation better than 30 dB. Another component is a wideband reconfigurable power splitter that has a 40% bandwidth, a return loss better than 20 dB in the worst case and the ability to achieve all power splitting ratios including switching between the two guides. In addition, a wideband reconfigurable phase shifter is designed to have 33% bandwidth and phase shift tuning range from 0o to 200o. Two coaxial-to-ridge gap waveguide transitions are designed to work over a more than 100% bandwidth to facilitate testing different ridge gap waveguide components. Analysis of the asymmetric double ridge waveguide is introduced where its impedance is deduced and may be used to design a single to double ridge waveguide transition useful for the dual-plane Butler matrix introduced here. In addition, this concept is used to develop a wideband unequal power divider in the single ridge waveguide technology. At the end, the whole system is assembled to show its performance in different tuning states. The ability of the system to produce radiation patterns of different characteristics is demonstrated. The presented Butler matrix design is a promising beamforming network for several applications like radar, base stations for mobile communications, and satellite applications

Design And Analysis Of Adaptive And Reconfigurable Antennas For Wireless Communication

Modern radar and communication systems have experienced a tremendous increase in the number of antennas onboard, on the ground, and in orbital space. This places a burden due to the confined volume and limited weight requirements especially in space applications. The reconfigurable antenna is a promising and exciting new type of antenna, where through the use of appropriate switches the antenna can be structurally reconfigured, to maintain the elements near their resonant dimensions for several frequency bands. This increases the bandwidth of the antenna dramatically, which enables the use of one antenna for several applications. Four novel reconfigurable antenna elements were designed to work at 2.45 GHz and at 5.78 GHz, to cover the transition period when wireless communication will shift to the 5.78 GHz band. The four elements designed are: the reconfigurable Yagi, the reconfigurable corner-fed triangular loop antenna, the reconfigurable center-fed equilateral triangular loop antenna and the reconfigurable rectangular-spiral antenna. None of these antennas have been reported in the literature. Simulation results for all four antennas were obtained using IE3D. Fabrication and measurements for the Yagi antenna was done and the measured results agree with simulations. All four antennas have very good performance with respect to the 3dB beamwidth and directivity. However the reconfigurable rectangular-spiral antenna is the most compact in size among all four antennas. It is (20 mm x 20 mm) in size. At 2.45 GHz it has a 3dB beamwidth of 87° and directivity of 6.47dB. As for the 5.78GHz frequency the 3dB beamwidth is 82.5° and the directivity is 7.16dB. This dissertation also introduces the use of reconfigurable antenna elements in adaptive arrays. An adaptive array that can null interference and direct its main lobe to the desired signal while being reconfigurable to maintain functionality at several frequency bands has the potential to revolutionize wireless communications in the future. Through several examples, at both the design frequencies, it is shown that the reconfigurable and adaptive antenna arrays are successful in nulling noises incident on the array. These examples illustrate how reconfigurable elements and adaptive arrays can be combined very beneficially for use in wireless communication systems

Autonomous smart antenna systems for future mobile devices

Along with the current trend of wireless technology innovation, wideband, compact size, low-profile, lightweight and multiple functional antenna and array designs are becoming more attractive in many applications. Conventional wireless systems utilise omni-directional or sectored antenna systems. The disadvantage of such antenna systems is that the electromagnetic energy, required by a particular user located in a certain direction, is radiated unnecessarily in every direction within the entire cell, hence causing interference to other users in the system. In order to limit this source of interference and direct the energy to the desired user, smart antenna systems have been investigated and developed. This thesis presents the design, simulation, fabrication and full implementation of a novel smart antenna system for future mobile applications. The design and characterisation of a novel antenna structure and four-element liner array geometry for smart antenna systems are proposed in the first stage of this study. Firstly, a miniaturised microstrip-fed planar monopole antenna with Archimedean spiral slots to cover WiFi/Bluetooth and LTE mobile applications has been demonstrated. The fundamental structure of the proposed antenna element is a circular patch, which operates in high frequency range, for the purpose of miniaturising the circuit dimension. In order to achieve a multi-band performance, Archimedean spiral slots, acting as resonance paths, have been etched on the circular patch antenna. Different shapes of Archimedean spiral slots have been investigated and compared. The miniaturised and optimised antenna achieves a bandwidth of 2.2GHz to 2.9GHz covering WiFi/Bluetooth (2.45GHz) and LTE (2.6GHz) mobile standards. Then a four-element linear antenna array geometry utilising the planar monopole elements with Archimedean spiral slots has been described. All the relevant parameters have been studied and evaluated. Different phase shifts are excited for the array elements, and the main beam scanning range has been simulated and analysed. The second stage of the study presents several feeding network structures, which control the amplitude and phase excitations of the smart antenna elements. Research begins with the basic Wilkinson power divider configuration. Then this thesis presents a compact feeding network for circular antenna array, reconfigurable feeding networks for tuning the operating frequency and polarisations, a feeding network on high resistivity silicon (HRS), and an ultrawide-band (UWB) feeding network covering from 0.5GHz to 10GHz. The UWB feeding network is used to establish the smart antenna array system. Different topologies of phase shifters are discussed in the third stage, including ferrite phase shifters and planar phase shifters using switched delay line and loaded transmission line technologies. Diodes, FETs, MMIC and MEMS are integrated into different configurations. Based on the comparison, a low loss and high accurate Hittite MMIC analogue phase shifter has been selected and fully evaluated for this implementation. For the purpose of impedance matching and field matching, compact and ultra wideband CPW-to-Microstrip transitions are utilised between the phase shifters, feeding network and antenna elements. Finally, the fully integrated smart antenna array achieves a 10dB reflection coefficient from 2.25GHz to 2.8GHz, which covers WiFi/Bluetooth (2.45GHz) and LTE (2.6GHz) mobile applications. By appropriately controlling the voltage on the phase shifters, the main beam of the antenna array is steered ±50° and ±52°, for 2.45GHz and 2.6GHz, respectively. Furthermore, the smart antenna array demonstrates a gain of 8.5dBi with 40° 3dB bandwidth in broadside direction, and has more than 10dB side lobe level suppression across the scan. The final stage of the study investigates hardware and software automatic control systems for the smart antenna array. Two microcontrollers PIC18F4550 and LPC1768 are utilised to build the control PCBs. Using the graphical user interfaces provided in this thesis, it is able to configure the beam steering of the smart antenna array, which allows the user to analyse and optimise the signal strength of the received WiFi signals around the mobile device. The design strategies proposed in this thesis contribute to the realisation of adaptable and autonomous smart phone systems

A 4.3 GHz BiCMOS VCO with multiple 360° variable phase outputs using the vector sum method

A 4.3 GHz voltage controlled oscillator (VCO) with multiple independently tunable phase outputs is presented. The VCO is realized by coupling two LC oscillators together in order to obtain quadrature signals and is tunable between 4.12 and 4.74 GHz. The variable phase outputs are achieved by varying the amplitudes of the in-phase and quadrature signals independently and then combining these signals together. By using multiple Gilbert cells as variable gain amplifiers (VGAs), multiple tunable phase outputs are achieved with the use of only one quadrature VCO. The VGAs are controlled using a custom non-linear digital-toanalog converter. The entire circuit is designed using a 3.3 V SiGe BiCMOS process. A maximum phase noise of -108.17 dBc/Hz was measured over the entire tuning range at a 1 MHz offset. The outputs of the VCO can be used as local oscillators that achieve phase shifting during radio frequency up or down conversion.Armscor S. A. Ltd and the Business Unit: Defence, Peace, Safety and Security (DPSS), Council for Scientific and Industrial Research (CSIR), South Africa.http://www.springerlink.com/content/0925-1030ai201