Design Of Active Antenna Research Articles

Mixed-Mode Sensitivity Analysis of a Combined Differential and Common Mode Active Receiving Antenna Providing Near-Hemispherical Field-of-View Coverage

A theoretical framework for a mixed differential and common mode sensitivity analysis of active receiving antennas is presented, which includes the derivation of a novel set of noise parameters for dual-mode balanced amplifiers. The analysis is applied to an example of a mixed-mode active wire antenna design, consisting of an integrated monopole and dipole structure. Results of numerical simulations and experimental measurements are presented which show that, for a single-polarized design, the judicious use of both differential and common modes enables the field-of-view coverage to be extended over the entire hemisphere with a variation in receiving sensitivity of less than 3 dB in the E-plane.

Design of Active Phased Array Antenna in Wind Profiling Radar

The active phased array antenna is a direction of modern radar development. But it is expensive. So the key in meteorological radar design is to get high ratio of capability and cost. We used 400 cross-polarization half wave diploes as radiation unit to get a high efficiency and reliability antenna, it also has low side lobe by Taylor weighting. 20 transmit/receive(T/R) modules produced too little heat to disperse, so it can be cooled by nature wind. 40 power dividers which one is divided into twenty parts and 1 power combiner decreased transmission loss. This antenna is fit for the need of wind profiling radar.

An accurate modeling technique for antennas and nonlinear RF power amplifier mixed simulation

The design of agile active antennas requires an efficient modeling methodology in order to quantify the impact of other components on the array radiation pattern, and especially the influence of power amplifiers (PA). Therefore, the performance prediction of PA on TX chains is of prime importance. This article describes two different approaches for active antenna applications. The first one concentrates on PA macro-modeling, which takes into account a large output load impedance mismatch with a voltage standing wave ratio up to 4:1. A PA behavioral model based on nonlinear scattering functions was developed and extracted from CW measurements. The model validity was checked by comparison with the measured data. The second one describes a novel technique for synthesizing a given radiation pattern, whereas taking into account the mutual coupling and calculated matching impedances (ZL ≠ 50 Ω) of each antenna in the array according to frequency and pointing angle.

Experimental Design of Mobile Satellite Antenna System for Commercial Use

This paper describes the receiver design of active phased array antenna (APAA) for mobile broadcasting and communications service via satellite. This system was optimally designed with RX-channels on the consideration of minimum size and cost besides electric performances. A dual-band and dual-polarized microstrip 8 × 4 array antenna was designed as a radiator. This antenna had high directivity and wide impedance bandwidth with dual-feeding structures such as the microstrip direct feeding for Band1 and the aperture coupled strip-line feeding structure for Band2. For system minimization, active channel blocks (ACBs) playing the role for signal amplification and phase control were directly combined behind the radiators with band pass filters (BPF). A beam-forming module was designed by 10:4 channel combining structure. Thus, the satellite signal power received from 10 radiators was combined into 4 channels for satellite auto tracking and signal demodulation on vehicles. Finally, to confirm the normal operations of the system, the outdoor communications test in a satellite communication environment was accomplished by the main terminal that provided satellite Internet service.

Computer-Aided Design of Ultra-Wideband Active Antennas by Means of a New Figure of Merit

In this letter, we address the design of a compact printed ultra-wideband antenna connected to a traveling-wave power amplifier. The antenna and the amplifier are first separately optimized by conventional means with 50 Omega terminations, which is found to result in suboptimal performance of the integrated assembly. The process is then repeated by a new design philosophy combining nonlinear harmonic-balance-based analysis with electromagnetic simulation. This approach makes use of a new figure of merit encompassing radiation and nonlinear performance, which allows the design goals to be formulated in terms of far-field performance. The proposed method leads to enhanced wideband radiation performance, strongly reducing the power density ripple across the band with respect to traditional techniques.

Active Integrated Antenna Design Using a Contact-Less, Proximity Coupled, Differentially Fed Technique

A novel contact-less, differential feeding technique suitable for integrated active antenna design is demonstrated. This technique utilizes an odd mode signal to generate fringing fields on either side of a microstrip gap under the antenna. This allows electromagnetic energy to be efficiently coupled from the transmission lines to the radiating antenna. In a balanced integrated antenna amplifier configuration, the proposed non-contact feeding method removes the need for any balun or power combining network. Hence in theory, a compact RF front-end design with lower losses can be realized. This feeding method has been successfully applied to the design of simple passive microstrip patch antennas and active integrated antennas (AIA). Simulated and measured results are also included to validate the proposed feeding concept and antenna designs. The performance of the proposed differential feeding technique on a simple microstrip patch antenna has been systematically studied. The study suggests that the proposed proximity method is broadband in nature, allowing antennas operating at different resonant frequencies to be swapped without the need to change the feed dimensions and without degrading the matching performance

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

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

Nonlinear antenna technology

Nonlinear antennas combine advances in nonlinear dynamics, active antenna design, and analog microelectronics to generate beam steering and beam forming across an array of nonlinear oscillators. Nonlinear antennas exploit two phenomena typically shunned in traditional designs: nonlinear unit cells and interelement coupling. The design stems from nonlinear coupled differential equation analysis that by virtue of the dynamic control is far less complex than the linear counterparts by eliminating the need for phase shifters and beam forming computers. These advantages arise from incorporating nonlinear dynamics rather than limiting the system to linear quasisteady state operation. A theoretical framework describing beam shaping and beam forming by exploiting the phase, amplitude, and coupling dynamics of nonlinear oscillator arrays is presented. Experimental demonstration of nonlinear beam steering is realized using analog microelectronics.

Zero-IF detection active antenna

A zero-IF receiver is implemented based on the active antenna design. The active devices, Schottky diodes, are compactly integrated with two patch antenna elements to act as the mixers. The active antenna can perform both direct-conversion demodulation and direction finding.

Integrated active antenna array using unidirectional dielectric radiators

In this paper, design considerations and experimental investigations of an integrated active antenna for space power combining that makes use of unidirectional dielectric radiators (UDRs) are presented and discussed. Attractive electrical performance stemming from proprieties of nonradiating dielectric waveguide structures is used to design a prototype at a frequency of 14 GHz. A UDR feed circuit is implemented by microstrip lines and aperture-coupling is studied experimentally for arrays of two, four and eight radiators. Measurements show high coupling and radiation efficiencies of the proposed excitation method. A power-combining efficiency of 89% was measured and a gain of 23.1 dBi was achieved for an antenna with eight radiators and four amplifiers. It is also shown that such a circuit configuration allows the combination of planar Ku-band monolithic hybrid microwave integrated circuit and UDR components in flexible design of active array antennas.

Analysis and design of integrated active circulator antennas

A study on the analysis and design of active integrated antennas based on active quasi-circulators is reported in this paper. The antenna consists of a novel hybrid active circulator and a short-circuited quarter-wavelength microstrip antenna, which combine to form an active antenna with transmit and receive action at the same frequency. A full-wave model of the configuration using the extended finite-difference time-domain method is devised to analyze its operation, to study parasitic electromagnetic coupling effects, and to derive design guidelines. Experimental results for a hybrid model are also presented.

Array Modeling for MM-Wave Active Integrated Antennas

The design of active integrated antennas operating in the millimeter-wave (mm-wave) range requires a two-fold analysis: on one hand, the electromagnetic modeling of large planar arrays; on the other hand, the characterization of the active devices. In this paper we face the former task, by presenting an efficient method for the calculation of the voltages induced on all the elements of a planar array by the input (gaussian) beam, and the evaluation of the impedance matrix of the array. These parameters, together with the modeling of the active devices, allow for a full characterization of the active integrated antenna.

Scanning leaky-wave antenna integrated with self-oscillating doubler

A new method which can enhance the scanning angle and elevate the operating frequency for active scanning leaky-wave antennas is proposed in this paper. We know that the characteristics and performance of scanning leaky-wave antennas are strongly dependent on the variation of the operating frequency within the leaky-mode region. The self-oscillating doubler without external oscillator sources provides double-frequency variation at the second-harmonic frequency instead of one-frequency variation at the fundamental frequency. Therefore, the antenna scanning range can be enhanced and the operating frequency can be elevated. The measured scanning angle of this antenna is 13°, which agrees well with the predicted 13.7°, and the data show that the frequency-scanning ability of the leaky-wave antenna using a self-oscillating doubler increases as predicted. This self-oscillating doubler design is very simple, and it not only can improve the scanning capability of the active leaky-wave antenna, but it is also very suitable for millimeter-wave active antenna design. ©1999 John Wiley & Sons, Inc. Microwave Opt Technol Lett 22: 108–111, 1999.

Aperture antenna shape prediction by feedforward neural networks

The emergence of adaptive "smart" materials has led to the design of active aperture antennas. Inherent in these antennas is the ability to change their shape in real time to meet various performance characteristics. When examining the usefulness of these antennas, one of the primary concerns is the antenna shape needed for a particular radiation pattern. Aperture antenna shape prediction is also a concern in the industrial production of semi-paraboloidal antennas. The work in this study employs an artificial neural network to model the aperture antenna shape in real time. To test the accuracy of the network, the "threefold holdout technique" was employed. In this technique, sets of examples are "held out" of the training process and used to obtain the "true error" of the network. The network accurately predicted the aperture shape exactly, to within three significant digits, 96% of the time.

Broadband active microstrip antenna for lower UHF applications

An impedance compensation method is used to integrate an active device with a microstrip patch antenna to design an active microstrip antenna for lower UHF applications. This method maintains the size-reduction aspect of the microstrip antenna. The fabricated active antenna is experimentally tested. The experimental findings reveal the suitability of this new method in broadband active microstrip antenna design for lower UHF applications. © 1997 John Wiley, & Sons, Inc.

Analysis of harmonic radiation from an integrated active antenna

A microstrip patch oscillator is modelled using a dual LCR Van der Pol oscillator. Closed form expressions are obtained for the fundamental and first harmonic voltage amplitudes and results show reasonably good agreement with a commercial circuit simulator. These type of expressions will be useful for computer aided design of active antennas and give circuit designers greater physical insight into their operation.

Analysis and application of nonleaky uniplanar structures with conductor backing

Novel conductor-backed uniplanar structures, including the nonleaky CPW and slotline, are analyzed and applied to the active antenna design. Both the spectral domain analysis and finite-difference time-domain techniques are used to simulate these circuits and to justify the numerical results. The measured gain of the novel active antenna is 1.7 dB higher than the conventional CPW antenna due to the unidirectional radiation of conductor-backed circuits. © 1996 John Wiley & Sons, Inc.

A new active array module for spatial power combiners and active antennas

We present the design and performance of a new module of spatial power combiners, which consists of four symmetrical slot coupled patch radiators and four MESFET negative resistance elements, based on a single active antenna design. These circuits are suitable for use in millimeter-wave systems as well as at microwave frequencies. Tests carried out with a prototype circuit showed a radiated power of 20.44 mW with about 16% DC-to-RF efficiency at 8.7 GHz. Feed networks for linear polarization and circular polarization are discussed. Design procedures for dual-frequency application are also addressed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Broadband active microstrip antenna design with the simplified real frequency technique

This paper deals with the design of broadband active microstrip antennas where the amplifier is integrated with the radiator. Theoretically sound definitions for gain and noise figure of the active antenna are introduced, and their relationships with the definitions for the composing circuit and radiator parts are explained. A sequential design procedure is presented that allows the straightforward and optimal design of transmitting and receiving antennas with multiple active stages, taking into account input and output matching, the gain-versus-frequency curve as well as the noise performance. The theoretical concepts are illustrated with two examples: one of a transmitting active antenna and one of a receiving antenna. The former one is a two-stage design that achieves nearly 25% of bandwidth with regard to gain and matching and 24 dB gain improvement as compared to the matched passive antenna. The second one is a receiving antenna (one stage) with a measured noise figure of 1.2 dB in a bandwidth of over 17% and a gain improvement of 11.9 dB over the corresponding passive antenna. Finally co- and cross-polar radiation patterns in E- and H-plane prove that the antennas also have favorable radiation characteristics in a wide bandwidth (at least 18%). >

A new approach to active antenna design

Design considerations for wide-band active antenna circuits for frequencies up to 30 MHz are presented. High performance is obtained by using unusual amplifier types having a virtually grounded input electrode of the input active device, and a large amount of negative feedback over several stages. The realized antennas with a physical length of 0.5 m have a flat frequency response from 5 kHz to 30 MHz and extremely low distortion (second-order intercept >+70 dBm, third-order intercept > +50 dBm). The antennas are thoroughly protected against statics; without sacrificing the high dynamic range. Output power levels up to +28 dBm can be handled. The electric field strength may exceed 10 V/m. The equivalent input noise field strength amounts to about 25 nV/m \sqrt{Hz} .