Showing papers on "Reflective array antenna published in 2012"

Simple and Efficient Decoupling of Compact Arrays With Parasitic Scatterers

Abstract: Compact arrays such as multiple antennas on a mobile terminal suffer from low efficiency and high correlation between antenna signals. In the present paper, a simple and rigorous procedure for decoupling two closely coupled antennas with a parasitic scatterer is proposed. The parasitic scatterer, which can be an additional antenna, acts as a shield between two active antenna elements. In contrast to previous studies involving the use of parasitic scatterer for decoupling antennas, we demonstrate using antenna impedances the underlying decoupling mechanism for two arbitrary antennas. By a proper choice of parameters, perfect matching and decoupling can be obtained for a given antenna spacing without extending the overall area used, and without introducing additional decoupling networks. The price to pay is a reduction of bandwidth relative to that of widely spaced antennas, which is the case for other decoupling methods as well. Simulation and experimental results are used to substantiate the effectiveness of the proposed design approach on a two-monopole array with an antenna spacing of 0.1 wavelength. Finally, several practical considerations of the proposal are also presented, including the extension of the approach for more than two active antennas and its implementation in mobile terminals.

Antenna Concepts for Millimeter-Wave Automotive Radar Sensors

Abstract: Automotive radars are on the market since 1999, both in the frequency range around 24 GHz as well as 76.5 GHz, with a new frequency band ranging from 77 to 81 GHz intended for medium and short-range sensors. The choice and design of the respective sensor antennas are determined by the requirement for high gain and low loss combined with small size and depth for vehicle integration, the challenges by the millimeter-wave frequency range, and a great cost pressure for this commercial application. Consequently, planar antennas are dominating in the lower frequency range, while lens and reflector antennas had been the first choice at 76.5 GHz, partly in folded configurations. With increasing requirements towards a much more detailed observation of the scenery in front or around the vehicle, multibeam antennas or scanning antennas have been designed, and solutions based on (digital) beamforming with a number of integrated antennas are in use or under development. General antenna concepts, partly including some system aspects, as well as three realized antenna configurations will be described in detail in this contribution.

Dielectric resonator array antenna

Abstract: Disclosed herein is a dielectric resonator array antenna including one or more series-feed type array elements installed to be arranged in parallel in a multilayer substrate, wherein first high frequency signals having the same or different phases or time delays are adjusted to be applied to the respective series-feed type array elements and respective radiated 1D array beams are individually used or combined to adjust beamforming of 2D array beams. Also, since the series-feed type array element is configured by connecting a plurality of dielectric resonator antennas in series, it can be easily and simply fed in series through coupling generated by the intervals between the feeding lines of the pertinent feeding unit of the plurality of dielectric resonator antennas connected in series. In addition, the broadband characteristics can be obtained by using the plurality of dielectric resonator antennas, whereby the overall antenna performance can be enhanced.

Measured propagation characteristics for very-large MIMO at 2.6 GHz

Abstract: Very-large multiple-input multiple-output (MIMO), also called massive MIMO, is a new technique that potentially can offer large network capacities in multi-user scenarios, where the base stations are equipped with a large number of antennas simultaneously serving multiple single-antenna users on the same frequency. We investigate channel behavior for a realistic outdoor base station scenario using large arrays. Specifically we compare dirty-paper coding (DPC) capacities and zero-forcing (ZF) sum-rates when using a physically large linear array and a compact cylindrical array, both having 128 antenna elements. As a base-line reference, we use the DPC capacity and ZF sum-rate for the ideal case with independent and identically distributed (i.i.d.) channel coefficients. The investigation shows that the measured channels, for both array types, often allow us to harvest most of the capacities/sum-rates achieved in the i.i.d. case, already at about 10 base station antennas per user.

Ring array antenna with optimized beamformer for Simultaneous Transmit And Receive

Abstract: In order to avoid self-interference, Simultaneous Transmit And Receive (STAR) systems require low mutual coupling between their respective transmit and receive antennas. This paper discusses the development of an 8-element transmit ring array antenna on a circular ground plane with a raised receive element. When combined with a beamformer that supplies linear progressive phase shifts to the array with opposing elements phased 180-degrees apart, the receive and transmit antennas are measured to exhibit 55 dB of isolation and omni-directional patterns in the 2.4 to 2.5 GHz band.

Automatic Design of CP-RLSA Antennas

Abstract: In this paper a procedure is presented, allowing the automatic design of circular polarized radial line slot antennas, with either pencil or shaped beam patterns. The antenna slot layout is refined by an optimization scheme based on the physical picture behind the working mechanism of the array. The validity of the approach has been proved by designing very efficient pencil beam antennas, either with maximum directivity or with controlled side lobe levels, and a shaped isoflux beam antenna.

Dual-Polarized Sinuous Antennas on Extended Hemispherical Silicon Lenses

Abstract: This paper examines the performance of dual-linear sinuous antennas on silicon extended hemispherical silicon dielectric lenses. A theoretical impedance of 106 Ω is identified based on the analysis of an ideal self-complementary structure, and this result compares well with simulations and measurements. The radiation properties of a linearly polarized sinuous antenna are simulated using Method of Moments software coupled to a GO/PO code, and also agree well with measurements. The results indicate that the sinuous antenna is an excellent wideband planar feed for a silicon lens, with cross-polarization levels below -17 dB, and polarization variations of ±5° over two octaves in frequency. The application areas are millimeter-wave, wideband, dual-polarized radio-astronomy receivers.

Integration of Array Antennas in Chip Package for 60-GHz Radios

Abstract: This paper discusses the integration of array antennas in chip packages for highly integrated 60-GHz radios. First, we evaluate fixed-beam array antennas, showing that most of them suffer from feed network complexity and require sophisticated process techniques to achieve enhanced performance. We describe the grid array antenna and show that is a good choice for fixed-beam array antenna applications due to its easy feed network design and manufacture. Then, we examine switched-beam array antennas using the Rotman lens or Butter matrix, illustrating that they allow scanning only in one plane and some miss a link even in the boresight direction. Nevertheless, a switched-beam array antenna uses a conceptually simple switch circuit to select the best signal path and may be a cost-effective approach to implementing steerable antennas in the 60-GHz band. Finally, we describe adaptive beam or phased array antennas and highlight the challenges and practical realizations of phased array antennas in both ceramic and organic chip packages for single-chip 60-GHz radios.

An Improved Design for a 1–18 GHz Double-Ridged Guide Horn Antenna

Abstract: It is a well known fact that the traditional 1-18 GHz double ridge guide horn (DRGH) antenna suffers from pattern deterioration above 12 GHz. At these frequencies, instead of maintaining a single main lobe radiation pattern, the pattern splits up into four lobes. It was shown in the literature that higher order modes are causing the pattern breakup. A benchmark study is performed to establish the performance of typical current and historic 1-18 GHz DRGH antennas. The performance of the antennas are evaluated in terms of gain, VSWR and radiation patterns. An improved 1-18 GHz DRGH antenna is presented. The new design has better gain and VSWR performance without any pattern deterioration. It also consists of significantly fewer parts, reducing the possibility of performance deterioration due to gaps between parts. Two prototypes of the new design were manufactured and tested with excellent agreement between measured and simulated results. The aperture dimensions of the new design are identical to that of the traditional DRGH, making it the only 1-18 GHz DRGH without pattern breakup whose aperture dimensions comply with the requirements specified in MIL-STD-461F - 24.2 by 13.6 cm.

SIW-Based Array Antennas With Sequential Feeding for X-Band Satellite Communication

Abstract: Novel phased array antennas suitable for X-band satellite communication are introduced and investigated for right-handed circular polarization (RHCP) in a multi-layered fabrication. The primary function of the proposed antennas is to transmit high quality data obtained from satellites and the ground station systems with the lowest amount of loss. For accurate data transmission, the important parameters regarding antenna specifications and electrical performance are the antenna gain and the high-purity polarization. Hence, this paper describes novel procedures for gain enhancements of the array antennas working at X-band (from 8.0 to 8.5 GHz) with an RHCP characteristic, including a single element, 2×2 array, and 2×4 array with four-way and eight-way power dividers, respectively. Taking into consideration the long-distance communication between a satellite and ground station, a substrate-integrated waveguide structure has been proposed, in particular because it is known to have low radiation loss and a low weight comparable to that of a microstrip, as well as low material loss similar to that of a metal-surrounded waveguide.

GPS/GNSS Antennas

Abstract: This practical resource provides a current and comprehensive treatment of GPS/GNSS antennas, taking into account modernized systems and new and developing applications. The book presents a number of key applications, describing corresponding receiver architectures and antenna details. You find important discussions on antenna characteristics, including theory of operation, gain, bandwidth, polarization, phase center, mutual coupling effects, and integration with active components. Moreover, you get expert guidance on the design of adaptive arrays and signal processing techniques used to mitigate interference such as jamming. Addressing critical GNSS antenna high precision requirements, this in-depth book explains the relationships between antenna gain, satellite visibility, geometric dilution of precision, and the carrier-to-noise density ratio. The book delineates requirements for both dual-band and tri-band antennas. You get detailed coverage of a wide range of antenna designs, including microstrip patch, quadrafilar helix, axial mode helix, spiral, inverted L, and planar inverted F antennas. Moreover, you find a discussion on new magnetic metamaterialu substrates and other dielectric substrate materials. Further, this comprehensive book presents designs for very compact GNSS antennas for personal handheld devices and automobiles.

CP metasurfaced antennas excited by LP sources

Abstract: A metasurface which is considered as a polarizer for microwave antennas is proposed in this paper. Preliminary results have shown that circularly polarized (CP) radiation can be obtained from linearly polarized (LP) source antennas with the use of metasurface, antenna performance such as realized gain, efficiency and bandwidth are improved simultaneously. The metasurfaced antennas have a succinct non-resonant cavity in sub-wavelength (1/13 λ 0 ) format.

Focal Distance Reduction of Transmit-Array Antennas Using Multiple Feeds

Abstract: The reduction of the focal distance of transmit-array antennas using multiple feeds is investigated theoretically and through full-wave simulations. A theoretical model of multiple-feed transmit arrays is derived using analytic formulas; it shows that the focal distance can be divided by a factor of two using a quadruple-feed configuration. The theoretical results are validated through full-wave simulations for two transmit arrays operating in the 60-GHz band.

UWB Antennas Beamforming Using Passive Time-Reversal Device

Abstract: In this letter, the feasibility of a new concept of passive antenna beamformer is investigated. The main idea is to develop a (1×N)-ports device in which the weightings on output ports are applied by time-reversal operation. The control of antennas weightings is then contained in the input waveform without the need of active components or external control signals. This approach is validated experimentally by radiation pattern measurement of a four-Vivaldi-antennas array, associated to a small reverberation cell beamformer. Finally, this concept is applied to realize a passive ultrawideband (UWB) phased-array radar for target imaging.

Surface Micromachined Millimeter-Wave Log-Periodic Dipole Array Antennas

Abstract: Two wideband millimeter-wave end-fire log-periodic dipole array (LPDA) antennas are designed and fabricated using a sequential surface micromachining. The antennas are excited by monolithically integrating a micro-coaxial line feed in the antenna's lower boom designed to provide band rejection at 60 GHz. Antennas 1 and 2 are designed to operate in 18-110 GHz and 18 GHz-50 GHz bands, and measured up to 40 GHz and 50 GHz, respectively. VSWR <; 2.5 is obtained for both antennas throughout the measured bandwidth. Measured directivity around 10 dBi and consistent E and H-plane 3 dB beamwidths around 56° and 72°, respectively, are obtained for Antenna 2 throughout its bandwidth. Good pattern correlation between measured and simulated results is also achieved. This paper clearly demonstrates that the wideband high-quality millimeter-wave end-fire LPDAs are now possible.

Large-scale multiple antenna fixed wireless systems for rural areas

Abstract: Multi-user multiple-input multiple-output (MU-MIMO) has a potential to realize cost effective high data rate internet access to the homes in rural areas. We propose the novel Ngara Access system where the central access point (AP) is equipped with a uniform circular array (UCA) installed on a high tower while each UT is equipped with a directional antenna free of clutter, providing predominantly line-of-sight (LoS) channel environment. Using a three dimensional geometric optics based channel model, we provide bit error probability simulation results which show that the spectral efficiency of the proposed system can be improved linearly as a function of the number of antenna elements at AP, without increasing the total transmitting power, provided a half wavelength antenna spacing is maintained and user groups of four or more are used to avoid ill-conditioned channel. Hardware demonstrators based on the proposed system have achieved the system spectral efficiency of 20 bits/s/Hz in an actual rural environment and of 67 bits/s/Hz in a laboratory environment at a lower UHF band.

Ground station antenna array for air to ground communication system

Abstract: A ground station antenna array includes a first array of antenna elements. A second array of antenna elements are vertically aligned with the first array of antenna elements. The first array of antenna elements and the second array of antenna elements are coupled to the digital beam forming circuitry and each cover a same sector of azimuth; the first array of antenna elements only covering a first elevation; the second array of antenna elements only covering a second lower elevation. The digital beam forming circuitry directs a radiation pattern of the first array of antenna elements in a first range of elevation angles, and directs a radiation pattern of the second array of antenna elements in a second range of elevation angles. The second array of antenna elements has higher gain than the first array. A respective transceiver is coupled to respective antenna elements of the first and second arrays.

A $W$ -Band Micromachined 3-D Cavity-Backed Patch Antenna Array With Integrated Diode Detector

Abstract: A 2 × 2 array of W-band air-dielectric cavity-backed patch antennas is presented. The array and its components are fabricated using a sequential surface micromachining technique known as the Polystrata process. Each antenna has a simulated 4.1% 10-dB return-loss bandwidth of about 94.5 GHz, a radiation efficiency of 95%, and a gain of 8.3 dB at broadside with a 76° 3-dB beamwidth. The simulated gain of the entire array is 13 dB. To facilitate system integration and measurement, several methods of interface are explored, including ground-signal-ground probing, direct transition to WR-10 waveguide, and hybridly integrated detector diodes. A measured return loss of 32 dB at 94 GHz with a 10-dB bandwidth of 3.25 GHz is measured for a single antenna, and 18 dB with a 10-dB bandwidth of 4.6 GHz is measured for an array. Measured E- and H-plane 3-dB beamwidths of 25° are reported. Antenna pattern measurements show good correlation with simulated results. The measured broadside gain for the antenna array is 13.5 dB at 94 GHz.

On roadside unit antenna measurements for vehicle-to-infrastructure communications

Abstract: In this paper, we discuss and analyze results from real-world vehicle-to-infrastructure measurements in an IEEE 802.11p-based vehicular ad hoc network. For our experiments we have used six roadside units (RSUs) mounted on highway gantries equipped with five different antenna types. We compare the performance of directional and omnidirectional antennas and analyze performance improvements in terms of coverage range and throughput, achievable by using directional antennas. Our results show that the use of directional antennas yields substantial performance improvements in IEEE 802.11p-based networks. However, for high-gain antennas even more careful RSU antenna positioning with respect to the lane geometry is required.

Comparison between Rectangular and Triangular Patch Antennas Arrays

Abstract: In this paper, several designs of micorstip arrays antennas, suitable for wireless communication applications, are presented This paper demonstrates several shapes of microstrip array antennas, such as rectangular and triangular patch antennas array Specifically, 4x1, 2x1, and single element of both shapes are designed and simulated by a full wave simulator (IE3d) Moreover, this paper presents a comparison between both rectangular and triangular antenna arrays Since, the resonance frequency of these antennas is 24 GHz, these antennas are suitable for ISM band and WLAN

A Novel Printed Wideband Dipole Antenna

Abstract: We present a novel technique to improve the input bandwidth of a conventional printed dipole antenna without actually increasing its size. We show that the proposed modification results in a considerable improvement in the input bandwidth. We also propose an equivalent circuit model for this antenna and describe a procedure to determine the values of the circuit elements. Finally, the performance of the antenna is demonstrated by a fabricated model and a comparison of experimental results with simulation.

Comparison between rectangular and triangular patch antennas array

Abstract: In this paper, several designs of micorstip arrays antennas, suitable for wireless communication applications, are presented. This paper demonstrates several shapes of microstrip array antennas, such as rectangular and triangular patch antennas array. Specifically, 4×1, 2×1, and single element of both shapes are designed and simulated by a full wave simulator (IE3d). Moreover, this paper presents a comparison between both rectangular and triangular antenna arrays. Since, the resonance frequency of these antennas is 2.4 GHz; these antennas are suitable for ISM band and WLAN

Three centuries of UWB antenna development

Abstract: This paper provides a historical overview of ultrawideband (UWB) antennas. Early radio was narrowband in conception, but UWB in practice due to various technical limitations. Oliver Lodge pioneered UWB antenna engineering in the nineteenth century with his invention of both the biconical and bowtie antennas, and J.C. Bose demonstrated the first horn antennas in 1897. These nineteenth century spark-gap UWB antennas were largely forgotten until the 1930s and 1940s when advances in RF technology made short wavelength compact UWB antennas more practical. For lack of wide-scale implementation, many of these mid-century designs were forgotten in turn. By the closing decades of the twentieth century, UWB antennas were still considered “the main limiting factor of a UWB system.” A third century of development kicked off (more-or-less) with the FCC's authorization of UWB wireless systems in 2002. A host of antenna designers re-discovered or reinvented twentieth century designs and advanced the UWB antenna arts further with innovations like compact planar implementations, UWB patch antennas, embedded UWB antennas, and spectral-filtered or frequency-notched designs. The three centuries of UWB antenna development have been characterized by the failure of successive generations of antenna designers to benefit from the lessons of earlier pioneers.

A 16-element transmit/receive Q-band electronically steerable subarray tile

Abstract: We report on a 44-GHz Transceiver Array architecture that integrates all required functionality for rf beamforming and radiation using a single 16-channel Silicon-Germanium rf beamforming integrated circuit, a 4×4 array of wide-scan patch antennas, and a compact, rugged, micromachined three-dimensional structure for rf and dc interconnect and thermal management. The subarray tile is fabricated using a wafer-scale millimeter-wave system and circuit integration method we call BATCH that has been developed to allow the embedding of one or more semiconductor dice having varied function and material into a compact chip-scale module. This circuit integration technology includes low loss planar transmission line interconnects and patch antennas with planar feeds, all embedded in a micromachined silicon interposer and suitable for high-volume batch fabrication.

Method and apparatus for beam forming and antenna tuning in a communication device

Abstract: A system that incorporates teachings of the subject disclosure may include, for example, determining antenna coupling among a plurality of antennas of the communication device and adjusting beam forming for the plurality of antennas utilizing phase shifters coupled with radiating elements of the plurality of antennas, where the adjusting of the beam forming is based on forming a desired antenna pattern that increases radiated throughput and reduces the antenna coupling among the plurality of antennas. Other embodiments are disclosed.

Design and measurement of automotive antennas for C2C applications

Abstract: Among the emerging wireless technologies, C2C communication has received considerable attention in the world because this technology promises to improve road safety and travel comfort. In this paper we present two C2C antennas that can be easily integrated into a conventional rooftop antenna module that includes also an element for GSM and UMTS services. The C2C antennas are a printed monopole and short circuited patch working at the TM01 mode. Antenna characteristics are investigated by S parameters and pattern measurements.

Design of compact reconfigurable switched line microstrip phase shifters for phased array antenna

Abstract: Wireless communication systems are evolving toward multi-functionality. This multi functionality and reconfigurability provides users with options of connecting to different kinds of wireless services for many purposes at different times by providing additional degrees of freedom in the system e.g. cognitive radio, MIMO systems and high performance phased arrays. Although Phase shifters are important component in many RF microwave subsystems e.g. radar, phased array antennas, beam forming networks, frequency translators yet the reconfigurable phase shifter provides additional degree of freedom in these systems by reconfiguring the phase shift at a given frequency. In this paper design and simulation of reconfigurable switched line phase shifter for phased array antenna using Ansoft HFSS 14 is presented. The reconfigurability is achieved by loading phase shifter using high frequency PIN diodes which acts as microwave switches. A compact reconfigurable phase shifter has been designed which gives a very low insertion loss ≈ −1 dB and wide range of linear reconfigurable phase shift over frequency from 1 to 5 GHz. The designed phase shifter gives reconfigurable phase shift for different application i.e. at 1.8 GHz (GSM), 2.4GHz (Wi-Fi), 3GHz (traffic control and collision avoidance radars), 3.6GHz (WLAN) by appropriate settings of the 8 switch positions. As designed phase shifter can be used for 360° beam steering in phased array antenna.

Influence of the Non-Linear UHF-RFID IC Impedance on the Backscatter Abilities of a T-Match Tag Antenna Design

Abstract: In ultra-high-frequency radio-frequency-identification (UHF-RFID) the conjugate complex matching of the packaged UHF-RFID transponder IC and the tag antenna structure is important to increase the reading range of the transponder tag Quite often half-wavelength dipole-like antenna structures are used Due to the fact that the impedances of the packaged IC and the dipole antenna structure are in different domains, a matching structure is needed to accomplish the conjugate complex matching A common technique to carry out the matching is the so called T-match Since the nominal input impedance of the IC depends on the applied antenna voltage (and in a strongly non-linear way), the backscatter abilities of the tag are also functions of the applied voltage In the present work those dependencies are investigated in terms of full-wave finite element simulations and measurements

C-shaped, E-shaped and U-slotted patch antennas: Size, bandwidth and cross-polarization characterizations

Abstract: A class of slotted antenna topologies have been compared with respect to their size, RF-performance and radiation properties. It has been shown that position and orientation of slots in these antennas can alter their properties in different ways. Comparison of these antenna topologies reveals that C-shaped and double C-shaped patch antennas are compact, narrow band antennas with relatively high cross-pol. The U-slotted and E-shaped patch antennas have been shown to have wide-band response with relatively large size.