Characteristics of a single fed circularly polarized microstrip antenna

The impedance and radiation characteristics are presented for a Single Fed Circularly Polarized (SFCP) square microstrip patch antenna with perturbation segments. The polarization behavior of this antenna is studied with the aid of various superstrates of different thickness. The complete design of the SFCP antenna is aided with the commercial software, Ensemble. A good agreement between simulated and experimental results is obtained

2009 Index IEEE Antennas and Wireless Propagation Letters Vol. 8

This index covers all technical items - papers, correspondence, reviews, etc. - that appeared in this periodical during the year, and items from previous years that were commented upon or corrected in this year. Departments and other items may also be covered if they have been judged to have archival value. The Author Index contains the primary entry for each item, listed under the first author\u27s name. The primary entry includes the coauthors\u27 names, the title of the paper or other item, and its location, specified by the publication abbreviation, year, month, and inclusive pagination. The Subject Index contains entries describing the item under all appropriate subject headings, plus the first author\u27s name, the publication abbreviation, month, and year, and inclusive pages. Note that the item title is found only under the primary entry in the Author Index

2008 Index IEEE Transactions on Control Systems Technology Vol. 16

This index covers all technical items - papers, correspondence, reviews, etc. - that appeared in this periodical during the year, and items from previous years that were commented upon or corrected in this year. Departments and other items may also be covered if they have been judged to have archival value. The Author Index contains the primary entry for each item, listed under the first author\u27s name. The primary entry includes the coauthors\u27 names, the title of the paper or other item, and its location, specified by the publication abbreviation, year, month, and inclusive pagination. The Subject Index contains entries describing the item under all appropriate subject headings, plus the first author\u27s name, the publication abbreviation, month, and year, and inclusive pages. Note that the item title is found only under the primary entry in the Author Index

Wideband circularly polarized fractal antenna with SSRR metasurface for 5G applications

In this study, a 3.5 GHz wideband circularly polarised antenna design is presented. The suggested antenna is constructed using square and flower fractal shapes within the patch. The square fractal shapes and flower fractals are implemented inside the slot patch and in the top left and right corners of the patch. The key advantage of using this method is to increase the bandwidth of the antenna besides reduce the size and improve the axial ratio. Then a Square Split Ring Resonator (SSRR) metasurface is added above the antenna for enhancement of gain and back lobe. The metasurface is added on the front of the antenna in order to increase the gain directivity and decrease the sidelobes and back lobe. Using computer simulation software (CST), the proposed metasurface antenna is simulated and then constructed on FR4 substrate with dimensions of (ε_r=4.4 and h=1.6 mm). Operating bandwidth between 1.79 GHz and 5 GHz is achieved, the metasurface antenna\u27s performance attained a fractional bandwidth of 91%. An improved gain of 3.05 dB is observed when metasurface is applied. A measured AR below 3 dB is achieved over the obtained bandwidth. The proposed fractal was reduced in size by 40.43% as compared to conventional antennas. The antenna recommended is suitable for use in the fifth generation (5G) applications

Millimeter-Wave Components and Antennas for Spatial and Polarization Diversity using PRGW Technology

The evolution of the wireless communication systems to the future generation is accompanied by a huge improvement in the system performance through providing a high data rate with low latency. These systems require access to millimeter wave (mmWave) bands, which offer several advantages such as physically smaller components and much wider bandwidthcomparedtomicrowavefrequencies. However, mmWavecomponentsstillneed a significant improvement to follow the rapid variations in future technologies. Although mmWave frequencies can carry more data, they are limited in terms of their penetration capabilities and their coverage range. Moreover, these frequencies avoid deploying traditional guiding technologies such as microstrip lines due to high radiation and material losses. Hence, utilizing new guiding structure techniques such as Printed Ridge Gap Waveguide (PRGW) is essential in future mmWave systems implementation. ThemainpurposeofthisthesisistodesignmmWavecomponents,antennasubsystems and utilize both in beam switching systems. The major mmWave components addressed in this thesis are hybrid coupler, crossover, and differential power divider where the host guidingstructureisthePRGW.Inaddition,variousdesignsfordifferentialfeedingPRGW antennas and antenna arrays are presented featuring wide bandwidth and high gain in mmWave band. Moreover, the integration of both the proposed components and the featured antennas is introduced. This can be considered as a significant step toward the requirements fulfillment of today's advanced communication systems enabling both space and polarization diversity. The proposed components are designed to meet the future ever-increasing consumer experience and technical requirements such as low loss, compact size, and low-cost fabrication. This directed the presented research to have a contribution into three major parts. The first part highlights the feeding structures, where mmWave PRGW directional couplers and differential feeding power divider are designed and validated. These components are among the most important passive elements of microwave circuits used in antennabeam-switchingnetworks. Different3-dBquadraturehybridcouplersandcrossover prototypes are proposed, featured with a compact size and a wide bandwidth beyond 10 % at 30 GHz. In the second part, a beam switching network implemented using hybrid couplers is presented. The proposed beam switching network is a 4 × 4 PRGW Butler matrix that used to feed a Magneto-electric (ME) dipole antenna array. As a result, a 2-D scanning antenna array with a compact size, wide bandwidth, and high radiation efficiency larger than84%isachieved. Furthergainenhancementof5dBiisachievedthroughdeployinga hybridgainenhancementtechniqueincludingAMCmushroomshapesaroundtheantenna array with a dielectric superstrate located in the broadside direction. The proposed scanning antenna array can be considered as a step toward the desired improvement in the data rate and coverage through enabling the space diversity for the communication link. The final activity is related to the development of high-gain wide-band mmWave antenna arrays for potential use in future mmWave applications. The first proposed configuration is a differential feeding circular polarized aperture antenna array implemented with PRGW technology. Differential feeding antenna designs offer more advantages than single- ended antennas for mmWave communications as they are easy to be integrated with differential mmWave monolithic ICs that have high common-mode rejection ratio providing an immunity of the environmental noise. The proposed differential feeding antenna array is designed and fabricated, which featured with a stable high gain and a high radiation efficiency over a wide bandwidth. Another proposed configuration is a dualpolarized ME-dipole PRGW antenna array for mmWave wireless communication. Dual polarizationisconsideredoneofthemostimportantantennasolutionsthatcansavecosts and space for modern communication systems. In addition, it is an effective strategy for multiple-input and multiple-output systems that can reduce the size of multiple antennas systems by utilizing extra orthogonal polarization. The proposed dual- polarized antenna array is designed to achieve a stable gain of 15 ± 1 dBi with low cross- polarization less than -30 dB over a wide frequency range of 20 % at 30 GHz

Performance Improvement of Dense Dielectric Patch Antenna using Partially Reflective Surfaces

Recently, millimeter-wave (MMW) band is being considered as the spectrum for future wireless communication systems. Several advantages are achieved by utilizing the millimeter-wave range, including high gain with large available bandwidth, compact size, and high security. Nevertheless, attenuation loss may restrict wireless communication systems’ transmission range. Meanwhile, printed antenna technology has gained the attention of antenna designers’ due to its low profile and ease of fabrication. High-gain antennas are very desirable as a critical part of MMW systems. Designing millimeter wave antennas with high gain characteristics would be a significant advantage due to their high sensitivity to atmospheric absorption losses. Moreover, planar configurations are required in many applications, such as for wireless communication. The main goal of this thesis is to design and propose state of the art designs of Fabry Pérot Cavity antenna (FPCA) designs with several types of superstrates to achieve high gain, wide bandwidth, and high efficiency to satisfy the requirements of today’s advanced wireless communication systems. A dense dielectric patch (DD) antenna is used as the main radiator and designed to operate at 28 GHz. The thesis presents several contributions related to the design and analysis of FPC antennas using several types of superstrates. The first research theme of this thesis has two parts. The first part presents a holey dielectric superstrate applied over a 2×2 dense dielectric square patch antenna array to enhance the gain, improve the bandwidth and efficiency, as well as to reduce the side lobe levels (SLLs). A dense dielectric patch replaces the metallic patch and is used as a radiated element. The measured results show a high gain of 16 dBi, with radiation efficiency of about 93 %, wide bandwidth of 15.3 %, and a reduced SLL. The second part focusses on a partially reflective surface (PRS) unit cell composed of two thin perforated dielectric slabs. The effect of the thicknesses of the unit cell dielectric slabs is discussed in detail. An array of the proposed PRS unit cell is applied over a dense dielectric square patch antenna array to broaden the bandwidth and to enhance the gain as well. The measured results exhibit a 3 dB gain bandwidth of 27 % with a high gain of 16.8 dBi. The second research theme presents an effective method to design a tapered superstrate of an FPC antenna with a DD patch element. This type of superstrate is designed to correct the phase above the superstrate to be almost uniform. The proposed single-layer perforated tapered superstrate is constructed by tapering the relative permittivity to be high in the center of the superstrate slab and then decrease gradually as it moves towards the edges. This tapered relative permittivity is then applied over a single DD patch antenna. The proposed antenna exhibits good performance in terms of the antenna gain and bandwidth. The antenna gain becomes flat and as high as 17.6 dBi. The antenna bandwidth is about 16 %, and the side lobe level of the antenna is very promising. A third theme presents the implementation and design of a high gain dense dielectric patch antenna integrated with a frequency-selective surface (FSS) superstrate. A 7×7-unit cell is used to build the superstrate layer, and applied above the high DD patch antenna. A modified unit cell is proposed to generate a positive reflection phase with high reflection magnitude within the frequency design in order to broaden the antenna bandwidth. A bandwidth of 15.3 % with a high gain of 16 dBi is obtained. Finally, a high gain linearly polarized (LP) substrate integrated waveguide (SIW) cavity antenna based on a high-order mode is implemented, fabricated, and tested. A TE440 mode is excited at 28 GHz. In this design, 4×4 slots are cut into the top metal of the cavity, where each slot is placed above each standing wave peak. These slot cuts contributed to a high gain of 16.4 dBi and radiation efficiency of about 96 %. The LP SIW cavity antenna was then integrated with a linear-to-circular polarization converter developed as a high gain circularly polarized (CP) SIW cavity antenna with high gain and high radiation efficiency of 16 dBi and 96 %, respectively

Microstrip patch antenna array with cosecant-squared radiation pattern profile

In this paper the radiation pattern on either side of the main beam, which is created by a standard microstrip patch antenna, is configured to correspond to a cosecant-squared curve. The 8×2 antenna array comprises eight pairs of radiating elements that are arranged in a symmetrical structure and excited through a single common feedline. Interaction of the fields generated by each pair of elements contribute towards the overall radiation characteristics. The proposed array is shown to exhibit an impedance bandwidth of 1.93 GHz from 9.97 to 11.90 GHz for S11 ≤ -10 dB with a peak gain of 14.95 dBi. The antenna’s radiation pattern follows a cosecant-squared curve over an angular range of ±60.91°. The compact antenna array has dimensions of 106×34×0.813 mm3. These characteristics qualify the antenna for radar applications at the X-band frequency

Miniaturization of Microstrip Patch Antennas for Gps Applications

The desire to incorporate multiple frequency bands of operation into personal communication devices has led to much research on reducing the size of antennas while maintaining adequate performance. GPS is one such application, where dual frequency operation, bandwidth and circular polarization pose major challenges when using traditional miniaturization techniques. Various loading methods have been studied to reduce the resonant frequency of the antenna – high permittivity dielectric loading, slot loading and cavity loading – while examining their effects on bandwidth and gain. The objective of this thesis is to provide guidelines on what is achievable using these miniaturization methods and insight into how to implement them effectively

Wide Band Embedded Slot Antennas for Biomedical, Harsh Environment, and Rescue Applications

For many designers, embedded antenna design is a very challenging task when designing embedded systems. Designing Antennas to given set of specifications is typically tailored to efficiently radiate the energy to free space with a certain radiation pattern and operating frequency range, but its design becomes even harder when embedded in multi-layer environment, being conformal to a surface, or matched to a wide range of loads (environments). In an effort to clarify the design process, we took a closer look at the key considerations for designing an embedded antenna. The design could be geared towards wireless/mobile platforms, wearable antennas, or body area network. Our group at UT has been involved in developing portable and embedded systems for multi-band operation for cell phones or laptops. The design of these antennas addressed single band/narrowband to multiband/wideband operation and provided over 7 bands within the cellular bands (850 MHz to 2 GHz). Typically the challenge is: many applications require ultra wide band operation, or operate at low frequency. Low frequency operation is very challenging if size is a constraint, and there is a need for demonstrating positive antenna gain