ITC/USA 2005 Conference Proceedings / The Forty-First Annual International Telemetering Conference and Technical Exhibition / October 24-27, 2005 / Riviera Hotel & Convention Center, Las Vegas, Nevada / Reconfigurable patch antenna integrated with RF mircoelectromechanical system (MEMS) switches is presented in this paper. The proposed antenna radiates circularly polarized wave at selectable dual frequencies (4.7 GHz and 7.5GHz) of high frequency ratio (1.6:1). The switches are incorporated into the diagonally-fed square patch for controlling the operation frequency, and a rectangular stub attached to the edge of the patch acts as the perturbation to produce the circular polarization. Gain of proposed antenna is 5 - 6dBi, and axial ratio satisfies 3dB criterion at both operating frequencies. The switches are monolithically integrated on quartz substrate. The antenna can be used in applications requiring frequency diversity of remarkable high frequency ratio.

Wireless networks face ever-changing demands on their spectrum and infrastructure resources such as, increased communication bands, capacity-intensive data applications, and the steady growth of worldwide wireless subscribers. This rapid increase in the use of wireless communication and the dependence on a reliable connectivity leads manufacturers to seek systems which are ever smaller, low power, provide long range, and high bandwidth, whilst giving higher reliable technologies. In modern communication systems MEMS is now finding its way, replacing older more high power and non-linear systems. One of the important components of RF MEMS technology is the implementation of MEMS phase shifters for phased array applications that require better performance than arrays of conventional phase shifters. An important example is where RF MEMS devices can be applied to vary the characteristics of an antenna, such as beam steering or tuning in a multiband antenna. The core of this thesis is the development and fabrication of a novel Parylene based MEMS phase shifter. This is the first novel application of Parylene as the strength member of the MEMS bridge. The implementation provided MEMS devices with lower actuation voltage of < 25 V. The fabricated phases shifters provide higher RF performance such as < 1 dB insertion loss, linearity of > 65 dBm, and return loss of < -15 dB. The reliability of the fabricated devices were tested beyond 2 billion switching cycles. This is higher than competing MEMS capacitive devices with a maximum lifetime of 500 million cycles. The fabricated device provides a maximum phase shift of 16.82° at 2.5 GHz, whilst the nominal value of phase shift was 5.4° at 2.5 GHz within the stable region of operation. The fabricated device provides comparable results with respect to reference DMTL designs. The research carried out in this thesis has lead to a number of international publications and four granted patents. The generic nature of this technology can open new opportunities in the conception and application of new MEMS devices in communication and sensing applications. The ability to deliver miniature, low power and high efficiency MEMS capacitive devices, will revolutionise the next generation of tuneable RF components suitable for mobile and handheld devices of the future.

Antenna is one of the most important components in wireless systems since signal transmission and reception are conducted through the antenna interface. Therefore, the signal quality is highly affected by the properties of the antenna. Traditional antennas integrated in devices such as laptops or cell phones have fixed radiation properties and can not be changed to adapt to different environments. Thus the performance of thefwhole system will be negatively affected since the antenna will not operate in the optimum status in different environments. To solve this problem, reconfigurable antenna, which can dynamically change its operation frequency, radiation pattern, and polarization, has gained a significant interest recently. Recongurable antennas are considered smart antennas, and can maximize the capacity of the wireless system. This dissertation focuses upon the theoretical analysis and design of smart antennas with recongurable radiation properties. The presented multi-functional reconfigurable antennas (MRAs) are aimed to applications in WLAN (wireless local area network) systems. The theoretical analysis of the MRA was rst investigated to validate the design concept, and then applied for practical applications. The multi-functional recongurable antenna array (MRAA), which is a new class of antenna array, is also created as a linear formation (4 1) of MRA, with theoretical analysis and design of the MRAA fully described. This work developed three MRA(A)s for practical implementation in WLAN systems. The rst design is the MRA operating in 802.11 b/g band (2.4-2.5 GHz), with nine beam steering directions in a parasitic layer-based MRA structure. The second is a MRA operating in 802.11ac band (5.17-5.83 GHz) with three beam steering directions in a simplied parasitic layer-based MRA structure. The third is a MRAA extension of the second design. The design process of these MRA(A)s is realized with the joint utilization of electromagnetic (EM) full-wave analysis and multi-objective genetic algorithm. All three MRA(A) designs have been fabricated and measured. The measured and simulated results agree well for both impedance and radiation characteristics. These prototypes can be directly employed in a WLAN system since practical limits have been taken into account with real switches and components implemented. Finally, this dissertation work concludes with plans for future work, which will focus on development of MRA(A)s with dual-frequency operation.

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Yes / This study proposes a compact design of frequency-reconfigurable antenna array for fifth generation (5G) cellular networks. Eight compact discrete- fed slot antennas are placed on the top portion of a mobile phone printedcircuit- board (PCB) to form a beam-steerable array. The frequency response of the antenna can be reconfigured to operate at either 28 GHz or 38 GHz, two of the candidate frequency bands for millimeter-wave (MM-Wave) 5G communications. The reconfigurability function of the proposed design can be achieved by implementing and biasing a pair of diodes across each T-shaped slot antenna element. Rogers RT 5880 with thickness of 0.508 mm and properties of ε = 2.2 and δ = 0.0009 has been used as the antenna substrate. The antenna element is very compact in size with a good end-fire radiation pattern in the frequency bands of interest. The proposed beam-steerable array provides very good 3D coverage. The simulation results show that the proposed design provides some good characteristics fitting the need of the 5G cellular communications. / Innovation programme under grant agreement H2020-MSCA-ITN-2016 SECRET-722424, UK Engineering and Physical Sciences Research Council (EPSRC) under grant EP/E022936/1

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yes / This paper presents a compact-size, low-cost smart antenna with electronically switchable radiation patterns, and reconfigurable polarizations. This antenna can be dynamically switched to realize three different polarizations including two orthogonal linear polarizations and one diagonally linear polarization. By closely placing several electronically reconfigurable parasitic elements around the driven antenna, the beam switching can be achieved in any of the three polarization states. In this design, a polarization reconfigurable square patch antenna with a simple feeding network is used as the driven element. The parasitic element is composed of a printed dipole with a PIN diode. Using different combinations of PIN diode ON/OFF states, the radiation pattern can be switched toward different directions to cover an angle range of 0◦ to 360◦ in the azimuth plane. The concept is confirmed by a series of measurements. This smart antenna has the advantages of compact size, low cost, low power consumption, reconfigurable polarizations, and beams.

Trough waveguides (TWG) have been utilized in a variety of radio frequency (RF) and other related applications including radar, the treatment of hypothermia and in the generation of plasmas. Perturbing the guided wave in these structures with blocks, rods, dielectrics, and other structures can create reconfigurable periodic line sources. These trough waveguide antennas (TWA) are then capable of providing both fixedfrequency and frequency-dependent beam steering. This was originally performed using electro-mechanical “cam-and-gear” mechanisms. Previous work related to the excitation of TWG and the performance of TWA topologies are limited when compared to more common antenna designs, yet they possess many desirable features that can be exploited in a modern system. This thesis will examines an S-band rectangular-to-trough waveguide transition and trough guide antenna that has been designed for broadband reconfigurable antenna applications considering as well the airflow characteristics for sensing applications. The design, fabrication, and electromagnetic performance (mode conversion, impedance matching, and antenna performance) are discussed, including the use of metallic cantilever perturbations placed along the troughguide sidewalls that are designed to provide improved impedance matching when steering the beam from the backward quadrant through broadside, towards the forward quadrant. Impedance matching techniques such as use of circular holes at the edge of each actuated cantilever are used to reduce power reflections and provide a low voltage standing wave ratio (VSWR) along the S-band. Finite element simulations will provide a demonstration of the airflow and turbulence characteristics throughout the entire structure, where the metallic cantilevers are used to manipulate the flow of air, to distribute it across the surfaces of the structure better and improve its potential for sensing operations.

With the fast adoption of LTE and IEEE 802.11N, more devices are employing multiple antennas to boost the data rate and reliability of the communication link. Traditionally, fixed antennas are used in such devices. In recent years, reconfigurable antennas have been sought out to further boost the performance, which can adaptor to the changing wireless channel by altering their radiation characteristics, and maintain or exceed the performance of fixed antennas. This thesis studies the possibility of performance increase using pattern reconfigurable antennas as receivers. Their performance potential was first estimated using simulations, and then demonstrated using two electrically steerable passive array radiator (ESPAR) antennas against a pair of monopole antennas on a hardware bit error rate (BER) testbed. The former produces equal performance in BER with certain pattern combinations and excels in theoretical capacity with substantial lead making pattern reconfigurable antenna a potent option as receiver in MIMO-related applications.