Broadband Electrically Small Circularly Polarized Directive Antenna

© 2013 IEEE. A broadband electrically small antenna with directive circularly polarized radiation is presented. It is composed of a compact single-feed crossed dipole driver, which is backed by a near-field resonant parasitic (NFRP) reflector to achieve the directive radiation pattern. The NFRP reflector is designed to generate extra resonances and minimum axial ratio (AR) points in the antenna system. These features are combined with those resulting from the driver to broaden the operational bandwidth. The proposed antenna was fabricated and measured. The antenna prototype, with a low profile (0.066 λo at 1.45 GHz) and an electrically small size (ka = 0.71 at 1.45 GHz), has a measured S11<-10 dB bandwidth of 25.66% (1.362-1.763 GHz) and a 3-dB AR bandwidth of 10.56% (1.390-1.545 GHz). Additionally, the measurements resulted in a broadside gain of 2.31 ± 0.4 dBic and an average radiation efficiency of 80% within the operational bandwidth

Broadband circularly polarized antennas for UHF SATCOM

Novel circularly polarized (CP) antenna configurations derived from Moxon type antenna (bent dipole element over a ground plane) for broadband VHF SATCOM applications. A sequence of topologies starting from a single vertical element to two vertical elements of the Moxon arms, then widened strip arm elements were studied. Further, arms were widened to bow tie structures with bents at 900.for achieving broadband operation. Bow tie elements were further split and optimized at a certain angle to achieve wider bandwidth. The logic in this evolution was to obtain highest possible gain based on Fano-Chu limits, which suggests that higher gain can be achieved in an electrically small antenna with maximized metallization in the structure that fill the volume. Circular polarization is obtained by two Moxon based cross elements that are fed through a hybrid 900 quadrature coupler. For the antennas that are prototyped, return loss S11 measurements were performed, and gains are simulated using HFSS. For the band of 225-400 MHz, antenna gain varies between 8-12 dB, and S11 is measured to be below 10 dB. Fabricated antennas coupled to a hybrid coupler yielded excellent bandwidths, low cross-polarization and low back lobes on the finite ground planes

A Wideband, Circularly Polarized, Directive Antenna With a Circular Reflector

A two-element, patch antenna with a single feed is presented to achieve wideband, circular polarization, and uni-directional radiation. The driven element of the antenna has a rotated, corner-truncated radiating patch to achieve circularly polarized radiation with an offset microstrip feedline in the front side. The back side of the driven element comprises a wide hexagonal slot, eight meander tips, and a parasitic patch in the center. A circular reflector is added behind the driven element to increase realized gain toward the front side direction of the driven element. A prototype of the antenna is fabricated for validation. In both simulation and measurement, the 3-dB axial ratio bandwidth is fully included in the -10-dB impedance bandwidth. In measurement, the proposed antenna has a -10-dB impedance bandwidth of 83% (1.58 GHz - 3.83 GHz), and a 3-dB axial ratio bandwidth of 49% (1.99 GHz - 3.27 GHz). Within the common band, the average realized gain is 6.1 dBic, and the peak realized gain is 8.6 dBic toward the front side direction of the antenna. The electrical size of the antenna is a kr of 1.69

Analysis of Miniaturized, Circularly Polarized Antennas for Bidirectional Propagation

Size reduction is necessary to fit the recent demand for small sized communication systems in consumer electronics. Wireless communication systems rely on antennas for long range transmission of signals, so size reduced antennas have been sought after in recent years. Also, not many antennas are designed for use in bidirectional scenarios like subways, tunnels, bridges, etc. Three sized reduced antennas with circular polarization are presented for use in bidirectional communication systems. An electrically small pattern reconfigurable array, an electrically small two-sided printed cross dipole, and a size reduced printed wideband antenna are introduced within this thesis. All antennas’ results are obtained from simulation, with two of the antenna designs being measured to verify their results

Moxon based RFID tag reader and GPS antenna

Modern communication applications at UHF frequencies require antennas with wide band, high forward gain, low backward radiation, high cross-polarization, small size and low manufacture cost. The Moxon antenna based on a two element Yagi-Uda antenna over the ground reflector is one of the most favorite antennas for HAM operators which can produce outstanding front to back ratio of radiated power, good match over the desired band and relatively low elevation height. A sequence of topologies has been proposed from a single vertical element to two vertical elements of the Moxon arms, until the lately patented Broadband Circularly Polarized Moxon Based Antennas for UHF satellite communications (SATCOM). The logic was to obtain the best possible performance based on Fano-Chu limits for electrically small antenna with maximum radiating elements in a given volume. This dissertation is an extension of this configuration to cover Radio Frequency IDentification (RFID) (850 MHz-1050 MHz) and Global Positioning System (GPS) (centered at 1227 MHz and 1575 MHz) bands. Prototype antennas are built based on HFSS-11 simulations and experimental measurements yielded satisfactory results. Various design parameters of the proposed complex antenna are optimized to obtain a significant size reduction and much improved performance than the commercial counterpart antennas

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

State-of-the-Art of Metamaterials: Characterization, Realization and Applications

Metamaterials is a large family of microwave structures that produces interesting ε and μ conditions with huge implications for numerous electromagnetic applications. Following a description of modern techniques to realize epsilon-negative, mu-negative and double-negative metamaterials, this paper explores recent literature on the use of metamaterials in hot research areas such as metamaterial-inspired microwave components, antenna applications and imaging. This contribution is meant to provide an updated overview of complex microwave engineering for the generation of different types of metamaterials and their application in topical electromagnetic scenarios

Reconfigurable circularly polarized cross-dipole antenna with a near-field resonant parasitic element

© Institution of Engineering and Technology.All Rights Reserved. This paper presents a polarization switchable circularly polarized (CP) antenna that consists of a compact single-feed crossed dipole loaded with a near-field resonant parasitic (NFRP) element. This antenna is placed above a metallic reflector to enhance its gain and broadside radiation pattern. A meander line with an arrowhead-shaped ending was applied to all arms of the crossed dipole and NFRP elements for compactness. By adjusting the end size of the NFRP element, the antenna was capable of switching its polarization from right-hand circular polarization to left-hand circular polarization and vice versa. The reconfigurability is realized by controlling the ON/OFF states of 8 PIN-diodes, which are inserted into the arrowhead endings of the NFRP element. For the RHCP mode, the antenna yields a |S11| 6.0 dBic and a radiation efficiency of > 70% across its operational bandwidth

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

Study and Implementation of Wideband Bow-Tie Antennas

Demand for multifunctional electronic devices is increasing in modern wireless communication systems. As the antenna plays a vital role in wireless communication, the need to design antennas which will provide better performance and more reliable communication is growing. In this thesis, innovative designs for antennas with wideband characteristic have been proposed to meet the demands of current multi-functional wireless communication systems. First, this thesis explores the design of a wideband pattern reconfigurable antenna with steady realized gain over the operating bandwidth. Another novel design of this thesis work is a highly directive wideband Yagi antenna. Finally, a two-planar structured CPLPDA antenna is designed to overcome the currently existing three-planar structured CPLPDA antenna’s complex design and fabrication process