No / It is shown that a conical beam 5.2-GHz antenna suitable for HIPERLAN application, but working in horizontal polarization, can be realized as a group of microstrip patch radiators in a ring formation. Layouts with three and four patches are described, and radiation patterns are found to agree well with predictions from a simple array model. The three-patch form is smaller and gives a closer approximation to an azimuth-independent pattern. Patterns are very similar to those achieved in vertical polarization with previously reported disk antenna realizations, giving peak radiation at about 50 elevation. Two methods of impedance matching are found to give satisfactory results. A dual-polarized conical-beam microstrip antenna, with a strictly uniplanar conductor pattern, is also presented and realized as an array of three square patches whose corners meet a central feed point. For the second polarization, the antenna functions as a series fed array. Fairly good conical beam patterns have been obtained, though only moderate polarization purity appears to be obtainable from threeelement arrays.

In this research work, we propose a novel energy harvester which converts solar electromagnetic radiation into DC energy at infrared regime. The proposed device consists of a dual polarized nanoantenna loaded with an anisotropic material at its gap. The dual polarized nanoantenna focuses the randomly polarized radiation into its gap resulting in high electric field. This high local electric field at the gap interacts with the anisotropic material. In our proposed design, the anisotropic material possesses nonlinear electrical conductivity and converts the dual polarizations at the gap into a DC voltage difference across the terminals of the nanoantenna. The novelty of our proposed design is in the rectification of the electromagnetic radiation without utilizing a diode. The theory of the energy harvester depends on the utilization of the dual polarized nanoantennas at high frequency regime. Therefore, we carry out a parametric study to investigate the resonance characteristic of the dual polarized nanoantenna. In addition, we investigate the effect of the geometrical parameters on the local field enhancement at the gap of the dual polarized nanoantenna. Also, another parametric study is carried out to determine the effect of the governing parameters of the anisotropic material on the generated DC voltage across the harvester. Our approach is illustrated through electromagnetic simulations. / Thesis / Master of Applied Science (MASc)

Due to the recent interest in broadband antennas a microstrip patch antenna was developed to meet the need for a cheap, low profile, broadband antenna. This antenna could be used in a wide range of applications such as in the communications industry for cell phones or satellite communication. Particle Swarm Optimization was used to design the dual-linear polarization broadband microstrip antenna and impedance matching network. This optimization method greatly reduced the time needed to find viable antenna parameters. A dual input patch antenna with over 30% bandwidth in the X-band was simulated using Ansoft's High Frequency Structural Simulator (HFSS) in conjunction with Particle Swarm Optimization. A single input and a dual input antenna was then fabricated. The fabricated antennas were composed of stacked microstrip patches over a set of bowtie apertures in the ground plane that were perpendicular to one another. A dual offset microstrip feedline was used to feed the aperture. Two different layers were used for the microstrip feedline of each polarization. The resulting measured impedance bandwidth was even wider than predicted. The antenna pattern was measured at several frequencies over the antenna bandwidth and was found to have good gain, consistent antenna patterns and low cross polarization.

<p dir="ltr">In this study we seek to evaluate the dry snow method of Z_DR calibration using dry snow as a target for X-band radars in comparison to vertical calibration scans. Numerous dates in the 2021 year were analyzed using the X-band Teaching and Research Radar (XTRRA) located on the Purdue University campus utilizing both vertical scans and azimuthal scans of dry snow. It was found that dry snow is still a potentially viable X-band calibration but several caveats, such as significant impacts from the protective dome around the radar, need to be addressed in order to make these results more robust.</p>

Owing to the need of high-directivity radiation in fix-point communication, this thesis designs the metamaterial with 4-fold rotational symmetric unitcells. Using their nearing-zero refractive index along two polarizations, we can get gain-enhanced antenna radomes and place them above dual- and circular-polarized antenna to verify our idea. It is known that the group delay variation in a communication system causes the degradation of symbol error rate, and positive group delay (GD) causes delay in signal propagation. Therefore, this research studies the negative group delay (NGD) behavior of metamaterial. Through analyzing the GD of metamaterial equivalent circuit caused by poles and zeros, we design a novel NGD bandpass circuit. Furthermore, this thesis develops graphic method for group delay investigatiion and study the relationship between NGD, loss and gain in order to simplify the design of GD compensation circuit.

Wind energy is one of the fastest-growing segments of the world energy market; however, wind energy facilities can have detrimental effects on wildlife, especially birds and bats. The ability to monitor vulnerable species in the vicinity of proposed wind sites could enable site selection that favors more vulnerable species, but current monitoring tools lack this classification capability. This work analyzes polarimetric and Doppler measurements of migrating birds for species based variation. A novel two stage feature extraction technique was developed to enable comparison between birds. Stage one involves mapping time changing radar measurements to the birds behavioral state in time (i.e. flapping and gliding); stage two uses this behavioral state information to produce temporal and statistical features that describe the frequency and appearance of these different behavioral states. General trends of temporal features (ex. wing-beat frequency) in the dataset match Ecological literature and validate the feature extraction approach. Preliminary clustering of bird detection data suggests possible species based subgroups of targets, although a larger dataset is needed for further validation.

This thesis deals with dual-polarized multiple input multiple output (MIMO) channels, an important issue for the practical deployment of multiple antenna systems. The MIMO architecture has the potential to dramatically improve the performance of wireless systems. Much of the focus of research has been on uni-polarized spatial MIMO configurations, the performance of which, is a strong function of the inter-element spacing. Thus the current trend of miniaturization, seems to be at odds with the implementation of spatial configurations in portable handheld devices. In this regard, dual-polarized antennas present an attractive alternative for realizing higher order MIMO architectures in compact devices. Unlike spatial channels, in the presence of polarization diversity, the subchannels of the MIMO channel matrix are not identically distributed. They differ in terms of average received power, envelope distributions, and correlation properties. In this thesis, we report on an indoor channel measurement campaign conducted at 2.4 GHz, to measure the copolarized and cross-polarized subchannels, under line-of-sight (LOS) and non-line-of-sight (NLOS) channel conditions. The measured data is then analyzed, to draw a fair comparison between spatial and dual-polarized MIMO systems, in terms of channel characteristics and achievable capacity. The main drawback of the MIMO architecture is that the gain in capacity comes at a cost of increased hardware complexity. Antenna selection is a technique using which we can alleviate this cost. We emphasize that this strategy is all the more relevant for compact devices, which are often constrained by complexity, power and cost. Using theoretical analysis and measurement results, this thesis investigates the performance of antenna selection in dual-polarized MIMO channels. Our results indicate that, antenna selection when combined with dual-polarized antennas, is an effective, low-complexity solution to the problem of realizing higher order MIMO architectures in compact devices.

A new technique for designing wideband dual-polarized cavity-backed slot antennas is presented. The structure is in the form of a double-resonant, dual-polarized slot antenna backed by a shallow substrate integrated cavity with a depth of approximately one tenth the free space wavelength. The presence of the cavity behind the slot enhances the antenna's directivity and reduces the possibility of surface wave propagation in the antenna substrate when the element is used in an array environment. Moreover, the dual-polarized nature of this radiating element may be exploited to synthesize any desired polarization (vertical, horizontal, RHCP, or LHCP). The double-resonant behavior observed in this substrate-integrated cavity-backed slot antenna (SICBSA) is utilized to enhance its bandwidth compared to a typical cavity-backed slot antenna. A prototype of the proposed antenna is fabricated and tested. Measurement results indicate that a bandwidth of 19%, an average gain of 5.3 dB, and a wideband differential isolation of 30 dB can be achieved using this technique. The principles of operation along with the measurement results of the fabricated prototype are presented and discussed in this dissertation. The SICBSA is investigated as a candidate for use as an array element. A uniform two element phased array is demonstrated to locate the main beam from boresight to thirty degrees. The potential effects of mutual coupling and surface wave propagation are considered and analyzed.

Yes / In this paper, we propose an eight-port/four-resonator slot antenna array with a dual-polarized function for multiple-input-multiple-output (MIMO) 5G mobile terminals. The design is composed of four dual-polarized square-ring slot radiators fed by pairs of microstrip-line structures. The radiation elements are designed to operate at 3.6 GHz and are located on the corners of the smartphone PCB. The squarering slot radiators provide good dual-polarization characteristic with similar performances in terms of fundamental radiation characteristics. In order to improve the isolation and also reduce the mutual coupling characteristic between the adjunct microstrip-line feeding ports of the dual-polarized radiators, a pair of circular-ring/open-ended parasitic structures is embedded across each square-ring slot radiator. The −10-dB impedance bandwidth of each antenna-element is 3.4–3.8 GHz. However, for −6-dB impedance bandwidth, this value is 600 MHz (3.3–3.9 GHz). The proposed MIMO antenna offers good S-parameters, high-gain radiation patterns, and sufficient total efficiencies, even though it is arranged on a high-loss FR-4 dielectric. The SAR function and the radiation characteristics of the proposed design in the vicinity of user-hand/userhead are studied. A prototype of the proposed smartphone antenna is fabricated, and good measurements are provided. The antenna provides good features with a potential application for use in the 5G mobile terminals. / This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement H2020-MSCA-ITN-2016 SECRET-722424. / Research Development Fund Publication Prize Award winner, January 2019.

The desire to counter multipath effects and improve communication links between mobile wireless systems in dense environment has led to much research in implementing antenna diversity. Space diversity, utilizing two or more antennas separated several wavelengths from one another, is one of the most popular method to achieve this operation. Meanwhile, polarization diversity, utilizing two orthogonal polarizations, has become more attractive in reducing cost and size of antenna systems. Polarization diversity is achieved using two orthogonal feeds to excite the two orthogonal polarization planes of the antenna. The challenge associated with designing dual polarized antennas is the need to reduce isolation between the feed and cross polarization level while maintaining a high efficiency. While a number of studies are successful in realizing polarization diversity, their antenna structure typically present more complex structures involving multiple layers. This thesis presents a novel method to implement polarization diversity on a miniature antenna using a simple planar structure. The antenna structure uses two crossed slots further miniaturized using a method derived from a recent study on miniaturized spiral slot antenna. At an operating frequency of ~ 1 GHz, the antenna is capable of achieving efficiency greater than 90% with a size as small as 0.08 .? x 0.08? The dual polarization operation is achieved by exciting the magnetic currents of the crossed slots with two orthogonal coplanar waveguide feeds. Simulation results of the proposed antenna yield an isolation > 15 dB with cross polarization levels > 10 dB. Theantenna structure was designed using CST Microwave Studio and the simulations were performed using IE3D simulation software.