Showing papers on "Antenna array published in 2012"

Scaling up MIMO: Opportunities and Challenges with Very Large Arrays

Abstract: This paper surveys recent advances in the area of very large MIMO systems. With very large MIMO, we think of systems that use antenna arrays with an order of magnitude more elements than in systems being built today, say a hundred antennas or more. Very large MIMO entails an unprecedented number of antennas simultaneously serving a much smaller number of terminals. The disparity in number emerges as a desirable operating condition and a practical one as well. The number of terminals that can be simultaneously served is limited, not by the number of antennas, but rather by our inability to acquire channel-state information for an unlimited number of terminals. Larger numbers of terminals can always be accommodated by combining very large MIMO technology with conventional time- and frequency-division multiplexing via OFDM. Very large MIMO arrays is a new research field both in communication theory, propagation, and electronics and represents a paradigm shift in the way of thinking both with regards to theory, systems and implementation. The ultimate vision of very large MIMO systems is that the antenna array would consist of small active antenna units, plugged into an (optical) fieldbus.

Out-of-Plane Reflection and Refraction of Light by Anisotropic Optical Antenna Metasurfaces with Phase Discontinuities

Abstract: Experiments on ultrathin anisotropic arrays of subwavelength optical antennas display out-of-plane refraction. A powerful three-dimensional (3D) extension of the recently demonstrated generalized laws of refraction and reflection shows that the interface imparts a tangential wavevector to the incident light leading to anomalous beams, which in general are noncoplanar with the incident beam. The refracted beam direction can be controlled by varying the angle between the plane of incidence and the antenna array.

94 GHz Substrate Integrated Monopulse Antenna Array

Abstract: A planar W-band monopulse antenna array is designed based on the substrate integrated waveguide (SIW) technology The sum-difference comparator, 16-way divider and 32 × 32 slot array antenna are all integrated on a single dielectric substrate in the compact layout through the low-cost PCB process Such a substrate integrated monopulse array is able to operate over 93 ~ 96 GHz with narrow-beam and high-gain The maximal gain is measured to be 258 dBi, while the maximal null-depth is measured to be - 437 dB This SIW monopulse antenna not only has advantages of low-cost, light, easy-fabrication, etc, but also has good performance validated by measurements It presents an excellent candidate for W-band directional-finding systems

Axial Ratio Bandwidth Enhancement of 60-GHz Substrate Integrated Waveguide-Fed Circularly Polarized LTCC Antenna Array

Abstract: A substrate integrated waveguide (SIW)-fed circularly polarized (CP) antenna array with a broad bandwidth of axial ratio (AR) is presented for 60-GHz wireless personal area networks (WPAN) applications. The widened AR bandwidth of an antenna element is achieved by positioning a slot-coupled rotated strip above a slot cut onto the broadwall of an SIW. A 4 × 4 antenna array is designed and fabricated using low temperature cofired ceramic (LTCC) technology. A metal-topped via fence is introduced around the strip to reduce the mutual coupling between the elements of the array. The measured results show that the AR bandwidth is more than 7 GHz. A stable boresight gain is greater than 12.5 dBic across the desired bandwidth of 57-64 GHz.

Method and apparatus for antenna array channel feedback

Abstract: A method (800) and apparatus (500) provide antenna array channel feedback The method (800) can include receiving (820), at a wireless terminal (500), a set of channel state information reference signals The method (800) can include determining (830) a precoding matrix based on the received set of channel state information reference signals The precoding matrix can have a representation in terms of three components The first component of the three components can be determined from a first set of vectors The second component of the three components can be determined from a first set of parameters The third component of the three components can be determined from a second set of parameters The second set of parameters can be a set of unit-magnitude scalars The method (800) can include transmitting (840), by the wireless terminal (500), a representation of at least one of the first component, the second component, and the third component

Modular antenna array with rf and baseband beamforming

Abstract: Generally, this disclosure provides systems and methods for a modular antenna array using radio frequency (RF) and baseband (BB) beamforming. A system may include a plurality of antenna modules, each of the antenna modules further including an array of antenna elements coupled to an RF beamforming circuit, the RF beamforming circuit to adjust phase shifts associated with the antenna elements to generate an antenna beam associated with the antenna module; and a central beamforming module coupled to each of the antenna modules, the central beamforming module to control the antenna beam associated with each of the antenna modules and to generate signal adjustments relative to each of the antenna modules, wherein the arrays of antenna elements of the antenna modules combine to operate as a composite antenna beamforming array.

Embroidered Conductive Fibers on Polymer Composite for Conformal Antennas

Abstract: We provide a novel class of conformal antennas based on embroidered conductive metal-polymer fibers (E-fiber) on polymer-ceramic composites. This new technology offers attractive mechanical and RF performance when compared to traditional flat and rigid circuits and antennas. The proposed E-fiber components are consisted of high strength and flexible polymer fiber cores and conductive metallic coatings. They were fabricated using automatic embroidery process, followed by assembly with polydimethylsiloxane and rare-earth titanate ceramic composites. Such composite substrates were tape-casted, and capable of providing tunable dielectric constant from 3 to 12 with a low tanδ <; 10-2 up to GHz frequencies. Basic RF prototypes, such as transmission lines (TL), patch antennas, and antenna arrays were fabricated for experimental evaluation. Measurement of the prototypes were conducted and compared to their copper counterparts. The RF characteristics of the E-fiber TLs exhibited an insertion loss of only 0.03 dB/cm higher than copper TLs up to 4 GHz . Also, the E-fiber patch antenna and antenna array exhibited 0.3 dB and 0.6 dB lower gains, respectively, than their copper counterparts. When applied onto a cylindrical surface, both the E-fiber patch antenna and antenna array only suffered 1 dB loss in realized gain, which is quite remarkable when compared with traditional antennas.

Electronically steered weather radar

Abstract: An electronically steered weather radar system comprises a plurality of transmit/receive modules, a plurality of antenna modules, and a system signal processor. Each transmit/receive module may be configured to adjust a phase characteristic of a radio frequency (RF) signal to be transmitted and received. Antenna modules may be in communication with transmit/receive modules and may form an antenna array configured to transmit a system beam in a direction determined by the phase of the RF signal from each transmit/receive module and to generate the RF signal from the received system beam. The system signal processor may be configured to perform a first scan to detect meteorological formations wherein the system signal processor communicates with each transmit/receive module to adjust a phase characteristic of the RF signals such that the antenna array transmits and receives the system beam through a plurality of azimuth angles and a plurality of elevation angles.

A 260 GHz fully integrated CMOS transceiver for wireless chip-to-chip communication

Abstract: A fully integrated 260GHz OOK transceiver is demonstrated in 65nm CMOS. Communication at 10Gb/s has been verified over a range of 40 mm. The Tx/Rx dual on-chip antenna array is implemented with half-width leaky wave antennas. Each Tx consists of a quadrupler driven by a class-D−1 PA with a distributed OOK modulator, and outputs +5 dBm of EIRP. The Rx uses a double balanced mixer to down-convert to a V-band IF signal that is amplified with a wideband IF driver and demoduated on-chip.

Dual-polarized optically controlled microwave antenna

Abstract: An optically controlled microwave antenna that reduces the optical power consumed by the antenna and to enable polarimetric detection an optically controlled microwave antenna comprises an antenna array and a feed for illuminating said antenna array with and/or receiving microwave radiation. The antenna array comprises a plurality of antenna elements each including a waveguide, two optically controllable semiconductor elements arranged within the waveguide in front of the light transmissive portion of the second end portion, a controllable light source arranged at or close to the light transmissive portion of the second end portion for projecting a controlled light beam onto said semiconductor element for controlling its material properties, and a septum arranged within the waveguide in front of the light transmissive portion of the second end portion and separating said waveguide into two waveguide portions.

60-GHz LTCC Integrated Circularly Polarized Helical Antenna Array

Abstract: A 60-GHz wideband circularly polarized (CP) helical antenna array of 4 × 4 elements is designed and fabricated using low temperature cofired ceramic (LTCC) technology. The flexible via hole distribution is fully utilized to achieve a helical antenna array to obtain good circular polarization performance. Meanwhile, grounded coplanar waveguide (GCPW) to stripline is utilized for probe station measurement. Unlike traditional helical antennas, the proposed helical antenna array is convenient for integrated applications. The fabricated antenna array has dimension of 12 × 10 × 2 mm3. The simulated and measured impedance, axial ratio (AR) and radiation pattern are studied and compared. The proposed antenna array shows a wide measured impedance bandwidth from 52.5 to 65.5 GHz for | S11| <; -10dB, wideband measured AR bandwidth from 54 to 66 GHz for AR <;3 dB, respectively.

Microwave antenna and antenna element

Abstract: A microwave antenna comprises an antenna array comprising a plurality of antenna elements. An antenna element comprises a cover, a hollow waveguide formed within the cover for guiding microwave radiation at an operating frequency between a first open end portion and a second end portion arranged opposite the first end portion, a septum arranged centrally and along the longitudinal direction within the waveguide and separating said waveguide into two waveguide portions, a substrate arrangement arranged at the second end portion within the cover, said substrate arrangement comprising a ground plane and line structures arranged on both sides of and at a distance from said ground plane and a substrate integrated waveguide, a waveguide transition arranged between said hollow waveguide and said substrate integrated waveguide, an integrated circuit arranged within said cover and electrically contacted to said ground plane and said line structures, and terminals electrically contacted to said integrated circuit.

Substrate Integrated Waveguide Cavity-Backed Wide Slot Antenna for 60-GHz Bands

Abstract: A wide slot antenna backed by a substrate integrated waveguide (SIW) cavity is presented and investigated for the enhancement of operating bandwidth at 60-GHz band. The 10-dB return loss impedance bandwidth of the antenna increases from 3% to 11.6% with consistent radiation performance as the width to length ratio (WLR) of the rectangular slot cutting from the SIW increases from 0.12 to 0.71. Its dual-resonance operation mechanism is verified by a parametric study. Three 2 × 4 antenna arrays with different slot WLRs are designed and fabricated with a printed circuit board (PCB) process at the 60-GHz bands. The measured results show that the antenna array with slot WLR of 0.71 achieves the gain of 10-12 dBi and the cross-polarization levels of better than 25 dB in both E- and H-planes over the enhanced operating bandwidth of about 11.6%.

Compact Multi-Band Antenna for Worldwide Mobile Handset Applications

Abstract: A multi-band antenna component is provided. The multi-band antenna component comprises a carrier, a first antenna array, and a second antenna array. The carrier is composed of a ceramic material characterized by a permittivity of at least about 6, said carrier having a first region and a second region distinct from the first region. The first antenna array is disposed on the first region and comprises one or more antennas selected from the group consisting of a first antenna adapted for about 2.4 GHz wireless communication, a second antenna adapted for about 5 GHz wireless communication, and a third antenna adapted for wireless communication for a global positioning system. The second antenna array is disposed on the second region and comprises at least one of a fourth antenna adapted for about 850 MHz wireless communication or a fifth antenna adapted for about 1800/1900 MHz wireless communication.

UWB Antennas for Communication Systems

Abstract: Since the U.S. Federal Communications Commission (FCC) opened the spectrum from 3.1 to 10.6 GHz for unlicensed radio applications with an EIRP of up to 41.3 dBm/MHz, numerous papers have been published on ultrawideband (UWB) antennas. Often the goal in these publications is to present an antenna, which has a satisfactory input reflection coefficient and a reasonable, constant radiation diagram versus frequency. However, in the case of UWB, there are numerous additional critical characteristics, which must be considered in the proper wireless system design. The publications, which treat this topic with sufficient proficiency, use such quantities as transient gain, group delay, ringing, dispersion, signal fidelity, polarization, efficiency, and the peak value of the transient response. For practical applications based on signals with an UWB instantaneous bandwidth occupation, all criteria are of vital importance, because they determine the sensor resolution, accuracy, or increase the bit error rate in communications systems. This paper gives an overview of UWB antenna designs together with their suitability for different applications with respect to the aforementioned critical characteristics. Additionally, UWB antenna array design, polarization diversity, and application in body area network (BAN) will be discussed. In nearly all cases the time-domain characteristics are taken into account, as they are more intuitive to interpret and very convenient for time-domain UWB system design.

Neural network applications in smart antenna arrays: A review

Abstract: Techniques employed in the synthesis of antenna arrays vary from complex analytical methods to iterative numerical methods based on optimisation algorithms. The drawback of these techniques is that they usually consider the array factor but not the interaction between array elements and real-time problems. This omission induces an error in the resultant radiation pattern; therefore, the physical relations between the array feeding details and the corresponding radiation patterns are taken into account to improve the accuracy. The behaviour of an antenna array is nonlinear in nature, resulting in an extremely high complexity using this approach, and it is usually disregarded. A neural-network-based solution can avoid complexity by establishing a relation between the desired radiation patterns and feeding details such as voltage and spacing in the real antenna array and can help convert the real array into a smart array. Several neural network applications in smart antenna array synthesis are reviewed in this paper.

Low-Cost and High-Efficient W-Band Substrate Integrated Waveguide Antenna Array Made of Printed Circuit Board Process

Abstract: A novel class of low-cost, small-footprint and high-gain antenna arrays is presented for W-band applications. A 4 × 4 antenna array is proposed and demonstrated using substrate-integrated waveguide (SIW) technology for the design of its feed network and longitudinal slots in the SIW top metallic surface to drive the array antenna elements. Dielectric cubes of low-permittivity material are placed on top of each 1 × 4 antenna array to increase the gain of the circular patch antenna elements. This new design is compared to a second 4 × 4 antenna array which, instead of dielectric cubes, uses vertically stacked Yagi-like parasitic director elements to increase the gain. Measured impedance bandwidths of the two 4 × 4 antenna arrays are about 7.5 GHz (94.2-101.8 GHz) at 18 ± 1 dB gain level, with radiation patterns and gains of the two arrays remaining nearly constant over this bandwidth. While the fabrication effort of the new array involving dielectric cubes is significantly reduced, its measured radiation efficiency of 81 percent is slightly lower compared to 90 percent of the Yagi-like design.

Dielectric Rod Antenna Array With Substrate Integrated Waveguide Planar Feed Network for Wideband Applications

Abstract: Dielectric rod antenna (DRA) elements have numerous advantages over conventional waveguide and horn antenna elements. They have low insertion loss, broadband input match, high mutual decoupling efficiency, and low-cost manufacturing. Additionally, the radiation pattern of the dielectric rod antenna is almost frequency-independent. However, its feeding is generally a challenge. This paper demonstrates a novel ultrawideband (UWB) eight-element DRA fed by a wideband substrate integrated waveguide (SIW) structure. The eight-way feed net work has less than 1.1 dB insertion loss and only ±0.9 dB and ±4° amplitude and phase imbalance, respectively. The developed low-cost and compact dual-layer DRA design covers over 40% bandwidth at X-band. It has a good input match, almost constant radiation pattern with a gain of 14.5 ± 2 dB over the frequency band, low dispersion, low squint performance, and almost flat group delay, which are essential requirements for many UWB ap plications. The developed array antenna is compact and occupies only 10 × 9 cm2.

140-GHz Planar Broadband LTCC SIW Slot Antenna Array

Abstract: A planar slot antenna array operating at 140-GHz band is presented and implemented using a low-temperature co-fired ceramic (LTCC) process. The array comprises a substrate integrated waveguide (SIW) feeding network and slot radiators with a dielectric loading. Considerations associated with the 140-GHz design and the effects of the dielectric loading on antenna performance are investigated. Measured results show that the boresight gain of a 4 t 4 antenna array including a transition from SIW to a waveguide is 16.3 dBi at 140 GHz and higher than 13.8 dBi over the operating bandwidth of 130-152 GHz. Therefore, the LTCC process offers one more option of planar broadband antenna array designs operating at upper millimeter wave bands.

A Low-Complexity GPS Anti-Spoofing Method Using a Multi-Antenna Array

Abstract: Spoofing attacks can completely mislead the position solution provided by global navigation satellite systems (GNSS). Recently, several anti-spoofing techniques have been introduced to combat spoofing attacks. However, in most cases the available anti-spoofing techniques are computationally complex or limited to a specific spoofing scenario. This paper provides a low computational complexity approach to mitigate the spoofing signals based on an antenna array processing technique. The proposed method is established based on the fact that all spoofing pseudo random noise (PRN) codes are transmitted from the same source in space. This technique steers a null toward a spatial sector where the maximum spatial energy is coming from. To avoid unintentional attenuation of authentic signals due to the beam pattern profile, the received power of each authentic signal is maximized individually after spoofing mitigation. The proposed anti-spoofing technique provides a low computational complexity process that performs prior to the acquisition stage of GPS receivers. Moreover, this method does not require any antenna array calibration process. Therefore, it can be easily employed as a stand-alone anti-spoofing module at the receiver input. Simulation results show that the proposed anti-spoofing method performs well for a wide range of received spoofing power. To verify the applicability of this method in real-world scenarios, a real data set has been collected and processed without any outdoor propagation. The data processing results demonstrate the desired performance of the proposed technique for real spoofing scenarios.

Supporting and Enabling Circuits for Antenna Arrays in Wireless Communications

Abstract: Antenna arrays have been demonstrated as a very promising technique for high-speed wireless networks, and are anticipated to be indispensable components in future wireless communication systems. This review paper presents an overview of the circuit techniques on combining signals from different receive array elements as well as splitting signals to different transmit array elements with emphasis on silicon-based solutions. It also reviews circuit techniques to control the phase and the amplitude of signals from/to each array element such that signals from those array elements can be combined and split in a desired manner for achieving high data rate communications as well as interference management.

Decoupling of Multiple Antennas in Terminals With Chassis Excitation Using Polarization Diversity, Angle Diversity and Current Control

Abstract: Excitation of the chassis enables single-antenna terminals to achieve good bandwidth and radiation performance, due to the entire chassis being utilized as the main radiator. In contrast, the same chassis excitation phenomenon complicates the design of multiple antennas for MIMO applications, since the same characteristic mode of the chassis may be effectively excited by more than one antenna, leading to strong mutual coupling and severe MIMO performance degradation. In this paper, we introduce a design concept for MIMO antennas to mitigate the chassis-induced mutual coupling, which is especially relevant for frequency bands below 1 GHz. We illustrate the design concept on a dual-antenna terminal at 0.93 GHz, where a folded monopole at one chassis edge excites the chassis' fundamental electric dipole mode and a coupled loop at the other chassis edge excites its own fundamental magnetic dipole mode. Since the two radiation modes are nearly orthogonal to each other, an isolation of over 30 dB is achieved. Moreover, we show that the antenna system can be conveniently modified for multiband operation, such as in the 900/1800/2600 MHz bands. Furthermore, by controlling the phase of the feed current on the folded monopole, the two antennas can be co-located on the same chassis edge with an isolation of over 20 dB. The co-located dual-antenna prototype was fabricated and verified in the measurements.

Nonuniformly Spaced Linear Antenna Array Design Using Firefly Algorithm

Abstract: A nonuniformly spaced linear antenna array with broadside radiation characteristics is synthesized using firefly algorithm and particle swarm optimization. The objective of the work is to find the optimum spacing between the radiating antenna elements which will create a predefined arbitrary radiation pattern. The excitation amplitudes of all the antenna elements are assumed to be constant. The optimum spacing between the array elements are obtained using firefly algorithm. The minimum allowed distance between the antenna elements is defined in such a way that mutual coupling between the elements can be ignored. Numerical analysis is performed to calculate the far-field radiation characteristics of the array. Two numerical examples are shown to form two different desired predefined radiation patterns. The performance of the firefly algorithm and particle swarm optimization is compared in terms of convergence rate and global best solution achieved. The performances of the optimized nonuniformly spaced arrays are analyzed. Finally, contour plots of the radiated power from the optimized array in the horizontal plane and vertical plane in the far-field region are provided.

Impact of Incomplete and Inaccurate Data Models on High Resolution Parameter Estimation in Multidimensional Channel Sounding

Abstract: Multidimensional channel sounding aims to estimate the geometrical structure of multi-path wave propagation in terms of directions of arrival/departure, Doppler shift, time delay, and complex polarimetric path weights. Maximum likelihood parameter estimation based upon an underlying data model is used to achieve high-resolution of the path parameters and, thus, renders possible an antenna independent channel characterization. However, any mismatch of the underlying data model to physical reality imposes limits to accuracy and reliability of the estimation. To cope with the limited resolution capability of the setup we are using a propagation data model that does not only contain discrete deterministic components but also a non-resolvable stochastic part. Joint estimation of both components considerably enhances the estimation quality and finally allows the interpretation as specular and diffuse contribution of multi-path propagation respectively. However, besides of noise influence, the achievable resolution is further limited by the accuracy of the data model that describes the measurement setup. Since the antenna characteristics are very susceptible to calibration and modeling errors, the directional estimates are most error-prone. We refer to the antenna array calibration procedure and discuss common pitfalls in high-resolution multi-path direction estimation that are related to inaccurate and/or incomplete device data model. Depending on the type of the antenna array (linear, circular) this will inherently produce biased and artificially spread angular estimates. Only with precise knowledge of the model errors the stochastic part can be identified as diffuse propagation component vs. modeling error.

DoA and Polarization Estimation for Arbitrary Array Configurations

Abstract: In this paper, algorithms for joint high-resolution direction-of-arrival (DoA) and polarization estimation using real-world arrays with imperfections are proposed. Both azimuth and elevation angles are considered. Partially correlated and coherent signals may be handled as well. Unlike most of the work available in the open literature, we consider the case when polarization sensitive antenna arrays, which may be disposed on a conformal surface, may have unknown (but fixed) geometries, be composed of elements with individual beampatterns and be subject to cross-polarization as well as mounting platform effects. Herein, recent results on steering vector modeling from noise-corrupted array calibration measurements are employed. This allows for incorporating all nonidealities of an antenna array into the estimation algorithms in a general and convenient manner. The proposed estimators can be implemented using the fast Fourier transform or polynomial rooting techniques regardless of the array configuration. The stochastic Cramer-Rao lower bound for the estimation problem at hand is established using the results from array steering vector modeling as well. The proposed expression takes into account array nonidealities, making such a bound tight even for real-world arrays. Extensive simulation results are provided using several real-world antenna arrays. The proposed algorithms outperform conventional algorithms available in the literature and have a performance close to the stochastic Cramer-Rao lower bound.

Advanced System Level Simulation Platform for Three-Dimensional UWB Through-Wall Imaging SAR Using Time-Domain Approach

Abstract: A previously developed simulation platform for localization purposes has been extended and customized to accurately analyze and simulate ultra wideband (UWB) through-wall imaging (TWI) synthetic aperture radar (SAR) systems as well. The newly added features/modules include electromagnetic simulator to account for wall presence and target scattering, a wideband backprojection imaging algorithm, and different transceiver architectures and antenna array configurations. The developed platform is capable of time gating to suppress early wall reflections and simulates various discrete components and functions of the UWB SAR system using both linear and nonlinear analysis. The simulator has been experimentally validated for both dielectric and metallic targets. The developed simulator can also be used to study various effects related to operation frequency, pulse width, pulse shape, wall dispersion, and carrier leakage. It predicts UWB system performance such as detection range, image resolution, and receiver dynamic range. The system's components can be re-optimized for high performance 3-D imaging based on our developed models. The simulation platform is also suitable for designing the optimal signal waveform that could improve the recovered image quality for TWI applications.

Exploiting multiple antennas for spectrum sensing in cognitive radio networks

Abstract: Spectrum sensing in wireless communications is provided to identify utilized and/or unutilized frequency bands reserved for primary users using a cyclostationary beamforming approach. An adaptive cross self-coherent restoral (ACS) algorithm can be utilized to extract signals of interest (SOI) at unique cycle frequencies related to primary and/or secondary users from an antenna array measurement. Based on the SOI, one or more users of the spectrum can be identified or the spectrum can be regarded as vacant; this can be based on lobe identification in the frequency spectrum of the SOI, in one example. This mechanism is less complex than traditional cyclic spectrum analysis methods. The cyclostationary beamforming based approach is more effective than the energy detection method. Also, the need for quiet periods in spectrum sensing is eliminated when using this mechanism such that signals can be transmitted simultaneously with receiving signals over the antenna array.

MAARSY: The new MST radar on Andøya—System description and first results

Abstract: [1] The Middle Atmosphere Alomar Radar System (MAARSY) on the North-Norwegian island Andoya is a 535 MHz monostatic radar with an active phased array antenna consisting of 433 Yagi antennas The 3-element Yagi antennas are arranged in an equilateral triangle grid forming a circular aperture of approximately 6300 m2 Each individual antenna is connected to its own transceiver with independent phase control and a scalable power output up to 2 kW This arrangement provides a very high flexibility of beam forming and beam steering with a symmetric radar beam of a minimum beam width of 36° allowing classical beam swinging operation as well as experiments with simultaneous multiple beams and the use of interferometric applications for improved studies of the Arctic atmosphere from the troposphere up to the lower thermosphere with high spatio-temporal resolution The installation of the antenna array was completed in August 2009 The radar control and data acquisition hardware as well as an initial expansion stage of 196 transceiver modules was installed in spring 2010 and upgraded to 343 transceiver modules in November 2010 The final extension to 433 transceiver modules has recently been completed in May 2011 Beside standard observations of tropospheric winds and Polar Mesosphere Summer Echoes, the first multi-beam experiments using up to 97 quasi-simultaneous beams in the mesosphere have been carried out in 2010 and 2011 These results provide a first insight into the horizontal variability of polar mesosphere summer and winter echoes with time resolutions between 3 and 9 minutes In addition, first meteor head echo observations were conducted during the Geminid meteor shower in December 2010

Development of a broadband horizontally polarized omnidirectional planar antenna and its array for base stations

Abstract: A novel broadband horizontally polarized (HP) omnidi- rectional planar antenna is developed for mobile communications. The proposed antenna consists of four printed arc dipoles that form a cir- cular loop for HP omnidirectional radiation. A broadband feeding net- work which includes four broadband baluns and an impedance match- ing circuit is designed to excite the four arc dipoles. An eight-element linear antenna array is developed for 2G/3G base stations. A broad- band power divider is used to feed the antenna array. Experimental results show that the HP omnidirectional antenna element has a band- width of 31% (1.66{2.27GHz) while its array has a bandwidth of 34% (1.67{2.35GHz) and an omnidirectional antenna gain of » 8dBi. Both of the antenna element and its array have good omnidirectivity over the 10-dB return loss bandwidth. Simulated and measured results for the antenna element and its array are presented.

High-Efficient Patch Antenna Array for E-Band Gigabyte Point-to-Point Wireless Services

Abstract: This letter presents a low-cost, high-gain, and high-efficiency 4 × 4 circular patch array antenna for gigabyte point-to-point wireless services at E-band (81-86 GHz). The antenna structure consists of two layers. The feed network is placed at the bottom layer, while the circular patches are on the top layer. To increase the efficiency of the antenna array, substrate integrated waveguide (SIW) is used to feed the circular patches through longitudinal slots etched on the top metallic surface. Low-cost printed circuit board (PCB) process is used to fabricate the antenna prototype. Simulated and measured bandwidths of the antenna array are 7.2%, which covers the desired frequency range of 81-86 GHz. Measured gain of the 4 × 4 antenna array is 18.5 dBi, which is almost constant within the antenna bandwidth. Measured radiation efficiency of 90.3% is obtained.