Showing papers on "Active antenna published in 2006"

Array thinning by using antennas in a Fabry-Perot cavity for gain enhancement

Abstract: A Fabry–Perot cavity (FPC) between a ground plane and a partially reflective surface (PRS) is used here to design array antennas with large distance between the radiating elements. This configuration provides some advantages: i) a reduction of the number of array elements to achieve high directivity; ii) large space between contiguous elements that may host a bulky feeding network as required for dual polarization or active antennas; iii) small coupling and easy feeding network designs because of the smaller number of elements with larger inter-element distance. We show that when designing the FPC antenna a frequency shift of the gain maximum may occur, especially in this sparse array configuration. We also show the existence of preferred distances between elements that controls both the directivity and the side lobe level, and how the presence of the FPC and the relaxed requirement of the interelement distance result in a lower interelement coupling. The presented dual polarized antenna comprises two interleaved 2 x 2 arrays placed in a 2-layer FPC, and exhibits a 19 dBi gain and 30 dB of isolation between the two ports over an operating bandwidth of approximately 5.7%, i.e., typical for patch antennas.

High-gain active composite right/left-handed leaky-wave antenna

Abstract: A novel high-gain active composite right/left-handed (CRLH) metamaterial leaky-wave antenna (LWA) is presented. This antenna, which is designed to operate at broadside, is constituted by passive CRLH leaky-wave sections interconnected by amplifiers, which regenerate the power progressively leaked out of the structure in the radiation process in order to increase the effective aperture of the antenna and thereby its gain. The gain is further enhanced by a matching regeneration effect induced by the quasi-unilateral nature of the amplifiers. Both the cases of quasi-uniform and binomial field distributions, corresponding to maximum directivity and minimum side-lobe level, respectively, have been described. An active LWA prototype is demonstrated in transmission mode with a gain enhancement of 8.9 dB compared to its passive counterpart. The proposed antenna can attain an arbitrarily high gain by simple increase of the length of the structure, without penalty in terms of return loss and without requiring a complicated feeding network like conventional array antennas

High gain active microstrip antenna for 60-GHz WLAN/WPAN applications

Abstract: A 60-GHz active microstrip antenna design comprising a three-stage pseudomorphic high electron mobility transistor amplifier integrated with a high gain antenna on an alumina substrate is presented. The amplifier has 18-dB gain and is ribbon bonded to the substrate on which the antenna is defined. The antenna is a microstrip array antenna with a simple etched pattern for producibility at high frequencies. Two antenna layouts are designed, for different coverage areas: a single array having 13.4-dBi directivity and a double array with 14.6-dBi directivity. Antenna losses are approximately 1-2 dB, giving antenna gains of about 12 and 13 dBi, respectively. Mechanical simplicity is achieved with this design, and unnecessary transitions are avoided. Measurements are performed on amplifier and antenna separately, as well as on the integrated design. Amplifier chips with and without benzocyclobutene passivation are fabricated and measured for comparison.

High gain active microstrip antenna for 60-GHz WLAN/WPAN applications

Abstract: A 60-GHz active microstrip antenna design comprising a three-stage pseudomorphic high electron mobility transistor amplifier integrated with a high gain antenna on an alumina substrate is presented. The amplifier has 18-dB gain and is ribbon bonded to the substrate on which the antenna is defined. The antenna is a microstrip array antenna with a simple etched pattern for producibility at high frequencies. Two antenna layouts are designed, for different coverage areas: a single array having 13.4-dBi directivity and a double array with 14.6-dBi directivity. Antenna losses are approximately 1-2 dB, giving antenna gains of about 12 and 13 dBi, respectively. Mechanical simplicity is achieved with this design, and unnecessary transitions are avoided. Measurements are performed on amplifier and antenna separately, as well as on the integrated design. Amplifier chips with and without benzocyclobutene passivation are fabricated and measured for comparison

Active Broad X-Band Circular Patch Antenna

Abstract: This letter presents the results of experimental study of omnidirectional circular patch antenna operating in the TM010 mode. Antenna geometrical parameters have been selected on the basis of theoretical calculations. It has been shown that the antenna of this kind with VSWR les 2 and bandwidth of 18% has a conical radiation pattern with maximum oriented 36deg to the zenith. The antenna has a side radiation level of -15 dB and a cross-component level of less than -25 dB. The experimental results are in good agreement with the theoretical calculations. Employment of the one-stage HEMT amplifier makes it possible to obtain the total gain of an active antenna of no less than 10 dB. This antenna can be successfully used for mobile systems, wireless indoor communications, as well as for array applications

Broadband high-efficiency circularly polarized active antenna and array for RF front-end application

Abstract: This paper presents a broadband high-efficiency circularly polarized (CP) active integrated antenna, and a broadband CP active array at 2 GHz. To realize the broadband CP antenna, a circular patch is aperture coupled by crossed slots in the ground plane, which are fed by an L-shaped microstrip feed line below the ground. The antenna is designed to serve the functions of both a radiator and a harmonics-terminated load for class-E high-efficiency power-amplifier (PA) integration. The broadband CP active antenna is realized by directly integrating the broadband CP antenna with the class-E PA. It achieves a 9% bandwidth (1.84-2.01 GHz) for axial ratio (AR) below 3 dB, and a 12% bandwidth for power-added efficiency (PAE) over 60%. To form the broadband CP active array, four active antenna elements are sequentially rotated, and each element is directly integrated with broadband class-E PA. A low-cost printed-circuit-board technology is employed in fabrication and a pseudomorphic high electron-mobility transistor is used. A peak drain efficiency of 71.5% for the class-E amplifier is measured at 1.95 GHz. The active array achieves a peak-effective radiated power of 39.7 dBm, and PAE is over 50% within a 22.6% bandwidth (1.72-2.16 GHz). The AR is below 3 dB over a 27% bandwidth (1.72-2.26 GHz).

Active phased array antenna for aircraft surveillance systems

Abstract: An active antenna is provided that includes an antenna element for transmitting RF transmit signals at a predetermined effective radiated power (ERP). An antenna module is configured to be mounted to an aircraft, with the antenna element being mounted to the antenna module. A connector module is provided at the antenna module and is configured to be coupled to a communications link and receive electrical transmit signals from the communications link. A transmit path is provided within the antenna module and extends between the antenna element and the connector module. A power amplifier is provided on the antenna module along the transmit path. The power amplifier increases a power level of the electrical transmit signals, received from the communications link, by a predetermined amount sufficient to drive the antenna element to transmit the RF transmit signals at the predetermined ERP.

A cross-layer approach to transmit antenna selection

Abstract: In this paper, we investigate a cross-layer approach to transmit antenna selection capable of adapting the number of active antennas to varying channel conditions. We address a cross-layer methodology in the sense that the criterion for the selection of antenna subsets is the maximization of link layer throughput which takes into account characteristics both at the physical and link layers. In order to enhance system performance, adaptive modulation is included to jointly perform antenna selection and rate adaptation. Performance assessment is conducted in terms of link layer throughput and transmission delay

Transmit-antenna selection for spatial multiplexing with ordered successive interference cancellation

Abstract: This letter proposes a low-complexity algorithm for transmit-antenna selection in a multi-input multi-output spatial multiplexing system with per-antenna rate control and an ordered successive interference cancellation receiver. The active antenna subset and its transmission rate are determined at the receiver, and conveyed to the transmitter using limited feedback. We propose a serial antenna-selection procedure consisting of a successive process that tests whether transmit-antenna selection gain exists when the antenna with the lowest signal-to-interference-plus-noise ratio (SINR) is discarded at each selection stage. Furthermore, we show that "reverse-detection ordering", whereby the signal with the lowest SINR is decoded at each stage of successive decoding, widens the disparities among fractions of the whole capacity allocated to each individual antenna, and thus maximizes a gain of antenna selection. Numerical results show that the proposed reverse-detection-ordering-based serial antenna selection induces a negligible capacity loss, compared with the exhaustive selection strategy, even with considerably reduced complexity.

RFID reader device having closely packed antennas

Abstract: A reader device for locating and tracking multiple tags includes a plurality of closely packed antenna circuits and at least one controller configured to control the plurality of closely packed antenna circuits. The at least one controller is configured to activate one or more of the antenna circuits to generate at least one resonance signal field configured to interrogate at least one tag associated with the one or more active antenna circuits while substantially preventing or reducing cross-coupling of signals between the one or more active antenna circuits and at least one antenna circuit within the at least one resonance signal field to a sufficiently low level, wherein the sufficiently low level substantially prevents misreads from unwanted tags, to thereby track the multiple tags in a substantially controlled manner.

Dual-band and dual-polarised microstrip antenna

Abstract: A microstrip antenna with dual-band and dual-polarisation operation, realised by electromagnetically feeding using a microstrip-T junction and CPW-line, is proposed and discussed. Since both ports of the antenna are electromagnetically coupled and separately placed on both layers of a substrate, the proposed antenna eliminates the need for capacitors in the RF path for multi-layered active antenna applications.

Broadband high-efficiency linearly and circularly polarized active integrated antennas

Abstract: This paper presents the design, fabrication, and measurements of two broadband high-efficiency active integrated antennas (AIAs) operating in linear polarization and circular polarization, respectively. A new design method is proposed for designing the broadband load network of the class-E power amplifier (PA), so that a high power-added efficiency (PAE) can be achieved over a broad bandwidth. A broadband high-efficiency class-E PA is designed based on the proposed method. The linearly polarized (LP) AIA is realized by integrating the broadband class-E PA with a broadband LP antenna, which uses a ring-slot coupled microstrip patch antenna. Then, the circularly polarized (CP) AIR is realized by integrating the broadband class-E PA with a broadband CP antenna, which uses a single-feed cross-slot-coupled microstrip patch antenna. Each antenna is designed for working as both a radiator and a harmonics-terminated load. A low-cost printed-circuit-board technology is employed in fabrication, and a p-high-electron mobility transistor is used. The PAE of the LP AIR is over 50% within a 14.6% bandwidth from 1.78 to 2.06 GHz, while the PAE of the CP AIA is over 50% within a 14% bandwidth from 1.92 to 2.21 GHz. The axial ratio of the CP AIA is below 3 dB over a 9% bandwidth from 1.99 to 2.18 GHz.

Broadband high-efficiency linearly and circularly polarized active integrated antennas

Abstract: This paper presents the design, fabrication, and measurements of two broadband high-efficiency active integrated antennas (AIAs) operating in linear polarization and circular polarization, respectively. A new design method is proposed for designing the broadband load network of the class-E power amplifier (PA), so that a high power-added efficiency (PAE) can be achieved over a broad bandwidth. A broadband high-efficiency class-E PA is designed based on the proposed method. The linearly polarized (LP) AIA is realized by integrating the broadband class-E PA with a broadband LP antenna, which uses a ring-slot coupled microstrip patch antenna. Then, the circularly polarized (CP) AIA is realized by integrating the broadband class-E PA with a broadband CP antenna, which uses a single-feed cross-slot-coupled microstrip patch antenna. Each antenna is designed for working as both a radiator and a harmonics-terminated load. A low-cost printed-circuit-board technology is employed in fabrication, and a p-high-electron mobility transistor is used. The PAE of the LP AIA is over 50% within a 14.6% bandwidth from 1.78 to 2.06 GHz, while the PAE of the CP AIA is over 50% within a 14% bandwidth from 1.92 to 2.21 GHz. The axial ratio of the CP AIA is below 3 dB over a 9% bandwidth from 1.99 to 2.18 GHz

A monolithic active conical horn antenna array for millimeter and submillimeter wave applications

Abstract: In this paper, a novel active integrated conical horn array is presented. Specifically, a 95 GHz quasioptically fed mixer integrated with an annular slot ring antenna was used as the basic element of the proposed active system. For efficient reception, a low cost micro-machined conical horn array was fabricated and placed on the top of active elements. A modified nonorthogonal finite-difference time-domain (FDTD) approach was applied for analyzing the basic conical horn antenna and a hybrid matrix manipulation technique for efficient antenna array modeling. The proposed active conical horn antenna array was fabricated and measured. Numerical simulations have verified the design at its distributed stages presenting very good agreement with the experimental data

A 24 GHz Active Antenna in Flip-Chip Technology with Integrated Frontend

Abstract: A novel slot antenna is presented which is realized using flip-chip technology and allows integration of active chips into the antenna. It is compatible with conventional planar assembly methods and exhibits resonant properties that can be used as an input/output filter. Combining 4 antennas one obtains a compact module with beam switching in all lateral directions. For 24 GHz, only 12 mm side length are required. The paper describes antenna design and presents measurement results of a 24 GHz version with integrated transmitter VCO.

High-efficiency class-B push¿pull amplifying array for microwave transmitting front end

Abstract: The authors present a novel push–pull amplifying array using quadruple antenna-patch couplers and dual-feed antennas. It exploits the advantages of both class-B push–pull amplifiers and active integrated antennas (AIAs), resulting in a high-efficiency, linear and yet compact design. A state-of-the-art heterojunction FET power amplifier of 50% peak power-added efficiency (PAE) is achieved at 10 GHz. A three-element array prototype was successfully built, achieving a peak antenna gain of 19.6 dBi. This is 5.7 and 10.4 dB better than amplifying arrays using the antenna-patch coupler approach and the conventional parallel feeding network, respectively.

Integrated MM-Wave MIMO Antenna with Directional Diversity using MEMS Technology

Abstract: This paper presents the design of a fully integrated antenna with directional diversity in the 60 GHz band using MEMS process on high resistivity silicon wafer. This active antenna designed for MIMO systems integrates switches and phase shifters.

Taking Advantage of a Schottky Junction Nonlinear Characteristic for Radiofrequency Temperature Sensing

Abstract: This paper presents a cost effective solution for remote radiofrequency temperature sensing, taking advantage of a Schottky junction nonlinear characteristic and the device integration in a properly designed dual-frequency radiator. Once the proposed integrated active antenna is interrogated with a CW excitation, the level and phase of the third harmonic response signal gives information of the tag temperature to be controlled.

Evaluation and compensation of mutual coupling and other non-idealities in small antenna arrays

Abstract: Smart antenna technology is a challenging area in the development of wireless communications. Using smart antennas the quality of a radio link can be improved by many ways. Smart antennas are active antenna arrays or groups with changeable complex-valued weights at inputs and outputs. Good electrical matching of the array and the similarity and ideality of element patterns is usually expected. This dissertation focuses on the problems in the smart antenna arrays caused mainly by mutual coupling. Mutual coupling causes reflected power in the feeding system, input/output signal correlation and corruption of the element patterns. The arrays used in this thesis are small microstrip arrays. The used frequency is about 5.3 GHz. For several arrays the element patterns and scattering matrices are measured and used in calculations and measurements. Also simulated patterns and scattering matrices are used. Due to mutual coupling the element patterns in an array are usually corrupted and therefore pattern correction should be used in smart antennas to improve the use of adaptive algorithms. In linear pattern correction the element patterns are reshaped using all antenna elements in the array. It is a computational method using a correction matrix between true and idealized inputs/outputs of array branches. For this pattern correction two basically different methods are used. The least squares error method can be used to find the correction matrix if the actual element patterns and the wanted element patterns are known, whereas in the scattering matrix method the correction matrix is defined only with the scattering matrix. These methods are compared in this thesis and the least squares error method is found to result in clearly better array patterns. The disadvantage of the scattering matrix method is that it does not compensate ground plate diffraction. However, the scattering matrix is easier to obtain than the element patterns and its use can give better understanding of the coupling mechanisms and therefore help the antenna design. Thus its use in pattern correction is examined more accurately. An extension of the least squares pattern correction method is done by correcting the array to a virtual array with different element spacing. The results show, that the element spacing in the virtual array should not differ significantly from the spacing in the real array. In addition to the pattern correction with a correction matrix the use of the real patterns for beamforming is examined. In a modified least squares method for beamforming the weighting (cost function) is used. The beamforming with and without robust weighting is compared on the relative scale and the use of weighting give better results. When antenna elements in an array are placed closer to each other, mutual coupling increases. At the same time the correlation between received signals increases. However, the signal correlation is usually caused by the signal propagation, and the effect of mutual coupling is minor. But, when signals arrive from many different directions, the pattern correlation caused by mutual coupling gives a realistic estimate of the signal correlation. The pattern correlation is a pure array characteristic and can be found easily. In this thesis the connection between pattern correlation and mutual coupling is examined. Equations are derived for this connection using scattering parameters or reflected power. These equations allow estimate mutual coupling from pattern correlation and vice versa, which is important for antenna array development. A more detailed formulation of the connection is done for lossless two-element arrays. In practice, when there are losses in the array, mutual coupling is not necessarily usable in estimation of pattern correlation.

Optimized Optical Links for High Spectral Purity Ku-band Signal Distribution

Abstract: Optical fibers constitute an attractive alternative to conventional wiring for the distribution of high spectral purity microwave signals. The main application here investigated is the remote synchronization and control in Ku-band of the elements of an onboard active antenna. The emphasis is put on the receiver which is realized using a synchronized oscillator.

Dual-band and dual-polarization patch antenna with high isolation characteristic

Abstract: A patch antenna with dual-band and dual-polarization operation is proposed and discussed. For feeding the antenna, it is used the electromagnetically coupled microstrip-T junction and coplanar waveguide (CPW)-line. Since both ports of the antenna are electromagnetically coupled, the proposed antenna eliminates the need for capacitors in the RF path for active antenna applications. By using CPW resonant cell, the demonstrated approach results in a significant improvement in port isolation.

A simple oscillator design with the frequency controlled by patch size

Abstract: A simple design for antenna-integrated planar oscillator with convenient controlling of operating frequency is presented. The oscillator circuit consists of a broadband negative-resistance active part and a passive load including a patch antenna. In the proposed design, patch antenna is resonator as well as radiating element. Hence, the antenna radiation frequency automatically becomes oscillation frequency. To verify the design method, two negative resistance circuits capable of supporting oscillation over full C-band and X-band are fabricated. The oscillation frequencies, output powers and phase noises at 100-KHz offset for different patch antennas are measured.

Integrated part tracking system

Abstract: An identification system includes a fractal antenna fashioned as a 2-dimensional data matrix which defines a Unique Item Identifier which operates as a conventional active antenna element for a RFID identification system while the unique face of the antenna is utilized as a physical reference to distinguish the component. By utilizing the face of an antenna as a Unique Item Identifier, an RFID system component antenna integrates two identification systems.

A directivity-diversity microstrip antenna array in millimeter wave

Abstract: The purpose of this paper is to report on a microstrip reconfigurable antenna in the millimeter-wave range. This antenna has directivity diversity and is based on a four-element array. An original method is outlined to guarantee matching for each configuration without changing circuit. Great results have been achieved with a passive prototype and an active antenna is under consideration. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1190–1194, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21569

GPS active antenna interface antisurging shock device

Abstract: The utility model relates to a GPS active antenna interface anti-surging impact device, which belongs to the technical field of communication. The utility model is used for solving the problem of surging impact. The utility model is characterized in that a combined discharging circuit is additionally arranged in a GPS active antenna interface circuit; the combined discharging circuit is composed of transient voltage restraint diodes D1 and D2, a resistor R, a capacitor C2 and an inductor L, wherein one end of the inductor L is connected with a radio freqency output port; the other end of the inductor L is connected with a power supply voltage-stabilization module B; the coupling-removing capacitor C2 is connected to the position between the inductor L and the ground; the transient voltage restraint diodes D1 and D2 and the resistor R form a surging absorption circuit and are connected with each other to form an n-shaped circuit; the other end of the transient voltage restraint diode D1 and the other end of the transient voltage restraint diode D2 are connected with the ground. The utility model rapidly absorbs the surging impact energy and protects sensitive components arranged in the module. The device is not the disposable protection and can effectively protect the GPS module for a long time. The utility model is easy for miniaturization and modularization.

Common integrated circuit for multiple antennas and methods

Abstract: In an active antenna system, two or more amplification chains are contained on one integrated circuit substrate or in one hybrid circuit The amplification chains can be connected to at least one of a plurality of radiating elements The integrated circuit or hybrid circuit can be incorporated into an active antenna connector, which can be electrically connected to a radiating element or a receiver system, for example A first integrated circuit or hybrid circuit can be exchanged with a second integrated circuit or hybrid circuit in a connector to adjust properties of an active antenna system

Broadband high-efficiency circularly polarized active antenna and array for RF front-end application

Abstract: This paper presents a broadband high-efficiency circularly polarized (CP) active integrated antenna, and a broadband CP active array at 2 GHz. To realize the broadband CP antenna, a circular patch is aperture coupled by crossed slots in the ground plane, which are fed by an L-shaped microstrip feed line below the ground. The antenna is designed to serve the functions of both a radiator and a harmonics-terminated load for class-E high-efficiency power-amplifier (PA) integration. The broadband CP active antenna is realized by directly integrating the broadband CP antenna with the class-E PA. It achieves a 9% bandwidth (1.84-2.01 GHz) for axial ratio (AR) below 3 dB, and a 12% bandwidth for power-added efficiency (PAE) over 60%. To form the broadband CP active array, four active antenna elements are sequentially rotated, and each element is directly integrated with broadband class-E PA. A low-cost printed-circuit-board technology is employed in fabrication and a pseudomorphic high electron-mobility transistor is used. A peak drain efficiency of 71.5% for the class-E amplifier is measured at 1.95 GHz. The active array achieves a peak-effective radiated power of 39.7 dBm, and PAE is over 50% within a 22.6% bandwidth (1.72-2.16 GHz). The AR is below 3 dB over a 27% bandwidth (1.72-2.26 GHz).

Electronic device with active antenna

Abstract: The utility model relates to an electronic device with a movable antenna, which comprises a device body and an antenna unit, wherein the antenna unit comprises an antenna fixing holder and an antenna body arranged on the antenna fixing holder One end of the antenna fixing holder is pivoted to the device body, and the antenna fixing holder can rotate between a retracting state and an out rotating state In the retracting state, the antenna fixing holder rotates towards the device body In the turning-out state, the antenna fixing holder rotates outwards the device body

Broadband circularly polarised high efficiency active antenna

Abstract: A broadband circularly polarised (CP) high efficiency active antenna is presented, where the antenna is integrated directly with a high efficiency class-E power amplifier (PA). The printed antenna is employed not only as a broadband CP radiator but also as a harmonics-termination load network for the class-E PA. Measured results demonstrate broadband CP radiation and high efficiency.