Big Antenna Research Articles

THE RADIO ASTRONOMIC METHOD FOR MEASURING THE EFFICIENCY OF ULTRA-HIGH FREQUENCY RECEIVING SYSTEMS

It is known that the working ability of a receiving system is best characterized by its effectiveness – the ratio between its effective space of the antenna to the noise tempera-ture of the system. With appearance of big antennas and high sensitivity receiving systems, the requirements set to measuring thеse parameters of antennas, such as noise tempera-ture, dissipation coefficient, effective space are increased. The Earth methods for investigating the parameters of high effective ultra-high fre-quency receiving systems turn out to be insufficient, and in some cases, impossible. Re-quirements to the parameters of today’s antennas constantly grow. The development of antenna techniques is not possible without adequate improvement and development of new methods for measuring antennas. The increase of geometrical sizes of the antenna is conditioned by the necessity of increasing the resolving power and effective space of antenna, which leads to the devel-opment of new methods for researching antenna characteristics. Such are the radio as-tronomy methods which are used largely nowadays. For measuring the parameters of big antennas, more than 10 cosmic sample sources, which satisfy the requirements to the measurement of antenna parameters with mirror aperture up to 80 m, have been selected. From those sample sources, for measuring the effectiveness in the Northern hemisphere of the earth in most cases Cassiopeia – A is used as the most powerful and non-setting etalon source. We have developed and experimentally researched the radio astronomy measure-ment method of effectiveness for UHF receiving systems which simplifies the measure-ment procedure compared to the existing methods, does not require calibration of the re-ceiving system which is important for decreasing the measurement error.

Comparative analysis of magnetic induction based communication techniques for wireless underground sensor networks.

A large range of applications have been identified based upon the communication of underground sensors deeply buried in the soil. The classical electromagnetic wave (EM) approach, which works well for terrestrial communication in air medium, when applied for this underground communication, suffers from significant challenges attributing to signal absorption by rocks, soil, or water contents, highly varying channel condition caused by soil characteristics, and requirement of big antennas. As a strong alternative of EM, various magnetic induction (MI) techniques have been introduced. These techniques basically depend upon the magnetic induction between two coupled coils associated with transceiver sensor nodes. This paper elaborates on three basic MI communication mechanisms i.e. direct MI transmission, MI waveguide transmission, and 3D coil MI communication with detailed discussion of their working mechanism, advantages and limitations. The comparative analysis of these MI techniques with each other as well as with EM wave method will facilitate the users in choosing the best method to offer enhanced transmission range (upto 250 m), reduced path loss (<100 dB), channel reliability, working bandwidth (1–2 kHz), & omni-directional coverage to realize the promising MI-based wireless underground sensor network (WUSN) applications.

Распределение сигналов синхронизации и данных цифровой антенной решетки на базе волоконно-оптических линий

The article deals with the practical aspects of synchronization and data transferring in multichannel phased array systems, especially in systems with big antenna dimensions. In multichannel passed array antenna commonly used an optical analog signals distribution scheme for RF and heterodyne signals and wired interfaces for control and digital data. For modern digital antennas the data transferring and synchronization method, based on digital fiber optic channels, was presented. The schemes, constructions, and algorithms of the method are described. The method was realized as SDR system using FPGA with soft-processor core. For data transferring the 8b/10b code is used. The following result of experiment are discussed: digital optical lines are resistant to signals distortions, can transfer big data massive with minimal delay, have excellent synchronization capabilities at quite low cost.

Different Techniques for Successful Handoff and Prevention of New Call Blocking Probability

The unsuccessful handoff and call dropping have been a fast growing, challenging and interesting area in real time application. The immense advancement in cellular networks communication study, has made tremendous improvement in the sphere of wireless technologies which are complementary to other and their union for specific area and services has created single wireless network system. The different wireless network systems having separate function have been combined under the concept of Next-Generation Wireless Communications Systems (NGNS) with a view to provide seamless high-quality wireless network services to mobile users. A set of mechanism are proposed for successful handoff process during the transfer of active calls or date session from one cell in a cellular network to another or from one channel in a cell to another maintaining uninterrupted service to a data session user. In this paper factors responsible for unsuccessful handoff and new call dropping probability method with probable control measures are reviewed. Methods are also proposed to increase handoff performance of mobile IP by decreasing the probability of false handoff initiation to a great extent under handoff management protocol of NGWS considering MT speed and handoff signaling which are directly proportional to false handoff initiation. In is reported that electromagnetic radiation is reduced to a considerable limit with the use of multi antennas instead of a single big antenna.

Imagining Future Cities: Aesthetic Design Guidelines for Wireless Small Cells in Urban Landscapes

Wireless towers with big antennas and large equipment shelters are decreasing as the primary type of wireless infrastructure in favor of more diversified designs, varying in size, network architecture, and capacity. The definitional boundary between typical macro sites of the 1990s and increasingly popular small cell networks are slowly blending as the backend architecture and the equipment on a site are designed to meet a greater variety of capacity and coverage needs through heterogeneous networks. As the design of wireless network architecture is changing, so are their appearance in our surrounding environment. As a result, municipal authorities are increasingly under pressure by the Federal Communication Commission (FCC) and wireless carriers to adapt and evolve their siting and permitting practices to accommodate a variety of different types of facilities. This paper will evaluate how innovation in LTE and 5G equipment is changing the design of physical wireless networks, establish an understanding of ‘contextual appropriateness’ in the blending of new small cells with the previously built environment, and prescribe aesthetic design guidelines for improving people’s experience with new urban wireless facilities. The methodology will include identifying technological trajectories and possibilities in wireless small cell designs, categorization of existing available assets for their deployment, an analysis of contextual appropriateness, and the development of objective design principles that will facilitate structured guidelines for network deployment. First, the paper will consider how wireless network equipment is evolving in different types of network topologies. Second, as small cells are typically placed on poles, these deployments will be categorized based on commonly available vertical assets in the Rights of Way, types of street furniture available for small cell integration opportunities, and other types of design ideas that leverage existing structures. Third, the definition of contextual appropriateness will be examined through city planning and architectural integration principles and typical constraints within the urban landscape. This paper will heavily utilize visual examples of previously deployed designs to analyze their technological components, design elements, and methods of construction and composition. Many of these visual examples are available in FCC docket filings relating to the recent relevant proceedings (WT Docket 17-79 and related), as well as in many articles and online government resources. Fourth, this research will contribute to a systematic method of evaluating the quality of small cell designs on a methodical basis, replacing the existing common practice of relying on subjective, improvised, and often contradictory aesthetic preferences. The resulting design recommendations and architectural best practices will facilitate many local efforts to develop preferential guidelines that achieve long-term compromise between preserving the character of their community and advancing to the smart cities of the future. The guidelines will also promote a more positive public perception and a more welcoming attitude toward the widespread integration of wireless facilities. The way that wireless technology will become deployed in the future of a given urban neighborhood will become its history, its character, and its legacy for advanced technological systems yet to come.

Optimization Design of Configuration and Layout for Queqiao Relay Satellite

According to the requirements of Chang’e 4 mission, the configuration and layout of Queqiao relay satellite are designed based on the mission analysis. The satellite’s shape, structure size, mechanical interface of launch vehicle adapter, module division, primary structure and equipment layout are determined. Based on small satellite’s platform and main structure, we optimized configuration and layout of structure size, solar array fixing, tank fixing, big antenna fixing. Combining with light-weighting technology and 3D printing technology, achieving a goal of zero-counterweight, the loading ratio reaches a high level of advanced small satellite. To pursue the tenet of “Simplicity, symmetry, and harmony”, the design ability is highlighted by combining the functionality and simplicity. It provides the reference to the similar satellite configuration and layout.

Virtual Antenna Array and Fractional Fourier Transform-Based TOA Estimation for Wireless Positioning.

In this paper, a novel virtual antenna array and fractional Fourier transform (FRFT)-based 2-dimension super-resolution time-of-arrival (TOA) estimation algorithm for OFDM WLAN systems has been proposed. The proposed algorithm employs channel frequency responses (CFRs) at the equi-spaced positions on a line or quasi-line moving trajectory, i.e., the CFRs of a virtual antenna array, to extract multipaths’ TOA information. Meanwhile, a new chirp-like quadratic function is used to approximate the channel multipaths’ phase variation across the space dimension, which is more reasonable than the traditional linear function, especially for relatively big virtual antenna array sizes. By exploiting the property of chirp-like multipaths’ energy concentration in the FRFT domain, the FRFT can be first used to separate chirp-like multipath components, then the existing TOA estimation methods in frequency domain can be further employed on the separated multipath components to obtain the multipaths’ TOA estimates. Therefore, the proposed algorithm can make more use of the multipaths’ characteristics in the space dimension, thus it can efficiently enhance the multipath resolution and achieve better multipaths’ TOA estimation performance without requiring a real antenna array. Simulation results demonstrate the effectiveness of the proposed algorithm.

Optimizing High-Power Ultra-Wideband Combined Antennas for Maximum Radiation Within Finite Aperture Area

In this paper, the combined antenna array is developed to maximize the effective potential gain (Gep) within finite aperture area for the high-power ultra-wideband (UWB) radiation. The idea is to make the antenna element as small as possible, so that more elements can be arranged within the prescribed aperture area to maximize Gep of the UWB system. On the other hand, the antenna element should match the pulse excitation. This means that in the frequency domain, the working band of the antenna element should cover the spectrum of the radiated pulse, and in the time domain, critical parameters of the radiated field (e.g., rise time of the monopolar pulse) should not be distorted, and those can be the principles for the UWB antenna to match the pulsed excitation, based on which the minimum size of the antenna element can be determined. With this method, a four-element combined antenna array is designed. Also, an impedance transformer and power divider are designed to feed the antenna array. Also, a big combined antenna is developed with the same aperture dimensions (30 cm × 30 cm) as the antenna array. Then, the performances of the antenna array and the big antenna are measured and compared. Compared with the big antenna, G <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ep</sub> of the antenna array is 21% higher under the applied excitation, which indicates that the proposed method can significantly improve G <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ep</sub> of the UWB system within the prescribed aperture area. Finally, the antenna array is furthermore optimized by adjusting the distances between the elements, and Gep is improved by another 11%, the total improvement is 33%, and the corresponding effective potential gain is 1.49.

WiFi-based through-the-wall presence detection of stationary and moving humans analyzing the doppler spectrum

Through-the-wall (TTW) sensing is relevant in several scenarios. In particular, a system able to detect the presence of a noncollaborative person behind a wall could be used by law enforcement for better planning actions in case of standoffs and hostage situations. For emergency situations, first responders could use such a system to detect the presence of people through rubble and collapsed structures. Traditionally, these types of systems have been designed using a radar approach. In particular, ultrawideband systems (2 GHz of bandwidth) have been proposed for detecting human presence by using radio frequency (RF) signals [1], [2]. These systems usually require a large power source and big antennas. Recently, to reduce the power and complexity of these devices, the use of opportunity signals, such as WiFi signals, has been considered [3]–[6].

A mighty antenna from a tiny CubeSat grows

By packing big antennas into small satellites, JPL engineers are making space science cheap

The high dynamics tracking capability for power descending in Chinese Chang’E-3 mission

As the exploration into the lunar and deep space becomes more diverse and profound, the flight process of the spacecraft is quite complex, which highly demands flight status monitoring and precise navigation. Accurate phase recovery in radio telecommunication is essential. This paper demonstrates the high dynamic tracking capability for power descending in Chinese Chang’E-3 mission, using open loop data recoding along with software phase lock loop tracking. Raw data recorded by Chinese Jiamusi and Kashi big antennas, as well as ESA’s New Norcia big antenna, have been used to recover the Doppler frequency for almost all the power descending phase. The standard deviation of phase tracking errors is around 5°. The phase tracking results and its variation characteristics are highly correlated with the flight events happening. The high dynamic phase tracking capability demonstrated in this paper have large flexibility and could be applied to flight operations in the future lunar and deep space missions.

Assessment of antenna characteristic effects on pedestrian and cyclists travel-time estimation based on Bluetooth and WiFi MAC addresses

Monitoring pedestrian and cyclists movement is an important area of research in transport, crowd safety, urban design and human behaviour assessment areas. Media Access Control (MAC) address data has been recently used as potential information for extracting features from people’s movement. MAC addresses are unique identifiers of WiFi and Bluetooth wireless technologies in smart electronics devices such as mobile phones, laptops and tablets. The unique number of each WiFi and Bluetooth MAC address can be captured and stored by MAC address scanners. MAC addresses data in fact allows for unannounced, non-participatory, and tracking of people. The use of MAC data for tracking people has been focused recently for applying in mass events, shopping centres, airports, train stations, etc. In terms of travel time estimation, setting up a scanner with a big value of antenna’s gain is usually recommended for highways and main roads to track vehicle’s movements, whereas big gains can have some drawbacks in case of pedestrian and cyclists. Pedestrian and cyclists mainly move in built distinctions and city pathways where there is significant noises from other fixed WiFi and Bluetooth. Big antenna’s gains will cover wide areas that results in scanning more samples from pedestrians and cyclists’ MAC device. However, anomalies (such fixed devices) may be captured that increase the complexity and processing time of data analysis. On the other hand, small gain antennas will have lesser anomalies in the data but at the cost of lower overall sample size of pedestrian and cyclist’s data. This paper studies the effect of antenna characteristics on MAC address data in terms of travel-time estimation for pedestrians and cyclists. The results of the empirical case study compare the effects of small and big antenna gains in order to suggest optimal set up for increasing the accuracy of pedestrians and cyclists’ travel-time estimation.

The Feasibility of Ocean Surface Current Measurement Using Pencil-Beam Rotating Scatterometer

Ocean current is highly related to the interaction between ocean and atmosphere. By measuring the speed and direction of the ocean current from space, we can investigate the ocean- atmosphere interaction on a global scale. The ocean-atmosphere interaction helps to maintain the balance that is essential for planet habitability. However, the conventional scatterometer is unable to measure the ocean current vector. To achieve this, a potentially feasible approach is to use a bigger antenna, a higher PRF, and measure the interferometric phase of two successive echoes. This paper derives four decorrelation factors, and provides the phase error model first. Then, an end-to-end simulation model is established, and it is used to analyze the feasibility of ocean surface current measurement from space. Based on the simulation model, the system parameters are optimized. The simulation results show that the current speed standard deviation (Std), which means the measurement accuracy, in along-track and cross-track direction is smaller than 0.1 m/s when the wind speed is larger than 4 m/s. The swath can be used for current vector inversion that is greater than 70% when the wind speed is larger than 7 m/s. Meanwhile, Kpc of the modified scatterometer is computed and the results show that Kpc is better than the traditional pencil-beam rotating scatterometer when the wind speed is larger than 6 m/s.

Radiation patterns of big antennas based on optics measurement

Radiation patterns of big antennas based on optics measurement

Quantifying and increasing the value of multi-azimuth seismic

Conventional marine exploration offshore Nile Delta is challenged by shallow heterogeneities and a deep, complex anhydrite layer called the Messinian. These subsurface complexities cause variable illumination and strong diffracted multiples resulting in imaging challenges below the anhydrite on conventional narrow-azimuth towed streamer acquisition because the recording antenna is too small (Figure 1a). Additionally, it has proved difficult to build the detailed depth migration velocity model required to correctly image below the Messinian layer. Multi-azimuth (MAZ) acquisition using time-domain processing however, has been very successful in addressing both the noise and illumination problems in the Nile Delta. The increased azimuthal and crossline offset coverage—bigger antenna—is achieved by acquiring six conventional marine surveys over the same area at 30° sail-line increments (Figure 1b).

Come Quiet Please

he manipulated the dials with scientific care until he knew he was zeroed in to a station. Then he switched on the powerful Zenith overrider and caught four channels, four conversations on his row of monitors. Gently he lifted the accordion from its case and turned it on. He hummed as it gathered force, then depressed a resonant chord. "Howdy, out there," he spoke into the microphone. "I know you have things to say to each other, you travelers of the night and truckers and bored people on the hill with the big antennas. This is the first time I've had full power since lightning run in on the old set last year, but I've got it up to where it ought to be now, and I can get my messages through to a whole world. That's good, and all I have for you folks is a song. It's gonna last about six or seven minutes, and then I'll be out of here. I want to dedicate it to the memory of Marjorie, and I guess the song could be called 'Marione,' even though she'd roll over if she knew I was doing this. This is Wade Timberly, and this is music for Miss Margie." It was a beautiful song, and he made it up as he played it. He used all the dexterity and complexity he had picked up from three decades of playing hymns and fight songs and polkas, but he used it to create an almost-transcendent simplicity. A song about clouds and rivers, about wind misbehaving in the trees and a blue heron lifting a fish in its beak. Dunes changed shape in the distance, and trawlers lifted their laden nets against the winter-blurred sun. A grackle lit on a garden trellis. Beach Elum blossoms were followed by fruit right as medallions and not at all sour. Migrating birds arced through the notes. Static from the CB cracked and sparkled, the puzzled voices of late-night listeners seeking information or solace or his attention through the chilling air. He didn't need for them to listen, but he didn't mind. He squeezed the bellows and his fingers danced a courtly dance of life wildly on the worn white keys. Come Quiet Please Come quiet please and hold my hand; Make haste for there is no more day; The shadows weave a wedding band Around a cloud of darkest grey. My lover's gone and left me now, My love, my dear, my sweetest face, And now I seek with my own words To fill that empty hollow place. My love, he loved me for a time When I was young and time was strong; Now silently a leaden chime Admits he did me somehow wrong. There's nothing left for me to love, No heart within to justify, No thought, no mind, no reason why And naught but grief left for a sky. -Barbara Deatherage 35 ...

Mechanical-transfer function and Brownian-noise measurements atT=4.2 K of a small (M=20.3 kg) gravitational-wave antenna using double “four-point” mechanical suspensions

Measurements atT=4.2 K of the mechanical-transfer function (m.t.f.) and of the Brownian noise of a small test antenna using a new type of suspensions are reported. These suspensions operate as a double mechanical filter and their m.t.f. has been measured in order to investigate their use for the big (5 t) gravitational-wave antenna now being assembled at CERN by the Rome group. The experimental results are in good agreement with the expected values.