Antenna Oscillator Research Articles

Управление спектром генерации в многоэлементных матрицах микрополосковых антенн-генераторов, работающих в режиме стохастизации колебаний

Active microstrip antennas, or antenna-oscillators (AOs) based on field-effect transistors, make it possible to create small-sized radiation sources in a wide frequency range, including the multi-element arrays with the possibility of power combining. The generation of radiation in the microwave range (5-20 GHz), depending on the conditions, can be single-frequency or multi-frequency, and the generation of noise-like signals was also observed. The combining of the AOs radiation power in the mode of oscillation stochastization is of the specific interest. In contrast to phased arrays, where power summation is achieved under conditions of synchronized monochromatic generators, the interaction of stochastic oscillation generators is a complicated process that leads to a radical change in the overall radiation spectrum. It seems more promising to combine the noise emission spectra and power of independent AOs with adjacent and controlled generation frequencies. In this paper, we study the possibilities to combine the power and emission spectra of a group of AOs, taking into account the possibility of their mutual synchronization.

Time Domain Measurement System for Electric Field of Radio Interference Generated by Corona Discharge

When corona discharge occurs around the wire, it will be accompanied by the movement of space charge, and then generate corona discharge effects such as radio interference and audible noise. In order to reveal time domain characteristics of the electric field of radio interference generated by corona discharge, a set of time domain measurement systems for radio interference, including oscillator antenna, sampling resistance, and data acquisition system, is developed. Based on the characteristics of corona-generated radio interference and antenna theory, the size of the antenna, the equivalent circuit model, and the selection of sampling resistance are discussed carefully to satisfy the requirements for the measurement of corona-generated radio interference. To verify the effectiveness of the measurement system, an experimental platform with a single corona source is built, and the time domain waveforms of corona current and radio interference are simultaneously measured. Besides, the attenuation law of radio interference is obtained by using a time domain measurement system. The results show that the amplitude of the measured voltage of radio interference decreases exponentially with distance. The time domain measurement system presented in this paper can lay a solid foundation for the time-domain evaluation of the radio interference level generated by corona discharge.

Experimental Realization of Silicon Micromachined Terahertz Diplexer-Antenna Module for Heterodyne Receiver

A novel integrated silicon micromachined diplexer-antenna module for compact terahertz (THz) heterodyne receiver is proposed. The module is composed of a radio frequency (RF) antenna, a local oscillator (LO) antenna, and a waveguide diplexer which are realized by using the silicon micromachining technology and stacking nine equal-thickness layers. The corrugated conical horn antenna and quasi-diagonal horn antenna are applied as the RF- and LO-antenna, respectively. The diplexer is composed of two third-order waveguide bandpass filters and an H-plane T-junction, providing the isolated RF and LO channels. An experimental study is carried out in the 340 GHz band, demonstrating its application potential in THz heterodyne receiver element and array.

Microstrip Antenna–Oscillators Integrated with a Waveguide Built in a Dielectric Substrate

The design of a microwave oscillator based on a microstrip log-periodic antenna integrated with a field effect transistor and a waveguide built in a dielectric substrate has been developed and analyzed. The waveguide geometry provides the possibility of propagation and radiation at both the fundamental frequency of the log-periodic antenna and harmonics. Computer simulation of the oscillator design in a frequency range near resonance frequencies of the log-periodic antenna is conducted. The possibility of summation of powers of several antenna–oscillators arranged ias a linear phased array is investigated.

Experiments study on attitude coupling control method for flexible spacecraft

High pointing accuracy and stabilization are significant for spacecrafts to carry out Earth observing, laser communication and space exploration missions. However, when a spacecraft undergoes large angle maneuver, the excited elastic oscillation of flexible appendages, for instance, solar wing and onboard antenna, would downgrade the performance of the spacecraft platform. This paper proposes a coupling control method, which synthesizes the adaptive sliding mode controller and the positive position feedback (PPF) controller, to control the attitude and suppress the elastic vibration simultaneously. Because of its prominent performance for attitude tracking and stabilization, the proposed method is capable of slewing the flexible spacecraft with a large angle. Also, the method is robust to parametric uncertainties of the spacecraft model. Numerical simulations are carried out with a hub-plate system which undergoes a single-axis attitude maneuver. An attitude control testbed for the flexible spacecraft is established and experiments are conducted to validate the coupling control method. Both numerical and experimental results demonstrate that the method discussed above can effectively decrease the stabilization time and improve the attitude accuracy of the flexible spacecraft.

MICROWAVE VECTOR REFLECTOMETER USING SELF-MIXING OSCILLATOR ANTENNAS

This paper presents a microwave reflectometer using self-mixing oscillator antennas. A unique characteristic of the proposed reflectometer is its simple structure without a circulator and a directional coupler. Each self-mixing oscillator antenna utilizes a Gunn diode as an active device and a rectangular waveguide as a resonator and a radiator. The determination of dielectric properties of materials was carried out at 9.79 GHz and the measured results using the proposed reflectometer were in good agreement with those by a dielectric probe. In addition, the reflectometer has several industrial applications, e.g. fruit classification, moisture content sensing, etc.

Generation of microwave radiation by active antennas with field-effect transistors locked by an external signal

Effects of locking by an external electromagnetic field of an array of oscillator antennas (OAs) designed by field-effect transistors integrated with log-periodic antennas are analyzed. The possibility of spatial combining of the radiation powers of OAs placed on a common dielectric substrate and arranged into a 1D array is demonstrated. It is shown that application of external locking can ensure severalfold broadening of the locking band of an ensemble of independent self-oscillators as compared to the case of mutual locking by a common field propagating in the dielectric substrate.

A Compact, Single-Layer Substrate Integrated Waveguide (SIW) Cavity-Backed Active Antenna Oscillator

This letter presents the design and implementation of a single-layer, cavity-backed antenna oscillator based on substrate integrated waveguide (SIW) technology. The proposed antenna topology is particularly suitable for two-dimensional array configurations. The active circuit and the radiator are placed on opposite sides of the substrate and within the cavity area, allowing for a compact implementation. An X-band prototype was designed and fabricated, and it features frequency-tuning capability introduced by employing a varactor diode in the active circuit. The measurements showed 11.87-12.36 GHz tuning range, phase noise better than - 107 dBc/Hz at 1 MHz offset, and 7% DC-to-RF conversion efficiency.

Tunable SIW cavity backed active antenna oscillator

A substrate integrated waveguide (SIW) cavity backed active slot antenna oscillator is proposed, the operation frequency of which can be tuned by means of a properly connected varactor. The cavity backed structure permits overcoming potential problems such as heat dissipation and unwanted surface wave modes in large array implementations, and may provide better phase noise performance. The use of SIW technology permits a cost-effective fabrication process and simple implementation at millimetre-wave frequency, for radar and communication applications. Full-wave FEM-based analysis is used for the design of the radiating structure, while harmonic balance and transient simulations are employed in the design of the active antenna oscillator and in the study of the stability of its steady-state solutions. Tunable active antenna prototypes have been implemented and measured.

An Iterative Technique for the Synthesis of Active Antenna Oscillator Arrays

A design procedure for the synthesis of a coupled active antenna oscillator array is presented. Such an array is synthesized by deriving two sets of parameters: the radiators' positions and the oscillators' outputs. The outputs are used to excite the radiators. Minimization of the mean square error between the desired pattern and the resulting one is made. Synthesis starts from an initial array, which is perturbed iteratively by varying simultaneously the element excitations and positions. In the iteration, the first variation of the cost function is set equal to zero. The final array results from the last iteration, where the stopping criteria are met. The procedure designs simultaneously both the antenna and the attached coupled oscillator array providing viable solutions. The second by properly configuring the tuning parameters through the use of closed-form formulas. The resulting arrays are shown to comply with the desired pattern and the nonlinear dynamics thus proving the validity of our method.

A Differential Voltage-Controlled Integrated Antenna Oscillator Based on Double-Sided Parallel-Strip Line

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> A voltage-controlled integrated antenna oscillator (VCIAO) integrating a differential voltage-controlled oscillator (VCO) with a double-sided parallel-strip line (DSPSL)-fed quasi-Yagi antenna based on the DSPSL is presented in this paper. The quasi-Yagi antenna is used not only as the radiating element, but also as the output power combiner and the resonating load of the differential VCO without any matching circuits or transition between them. The two sub-oscillators of the VCO on the opposite sides of the substrate share a common quarter-wavelength DSPSL resonator and a common inserted ground plane, which also works as the reflecting element for the quasi-Yagi antenna. The common DSPSL resonator terminated by a series varactor can not only help to synchronize the two sub-oscillators, but also realize tunable oscillating frequency. Due to the differential output of the proposed VCO, the cross polarization of the proposed VCIAO is suppressed to a great extent in the entire tunable frequency range. </para>

Small-Size X-Band Active Integrated Antenna With Feedback Loop

A small-sized active integrated antenna (AIA), consisting of a transmission feedback oscillator loaded with a microstrip antenna is presented in this paper. The oscillator antenna, which consists of a NEC super low noise high frequency field effect transistor (HF FET) integrated into the center of a segmented patch antenna, was designed for X-band at 8.50 GHz, and occupies a 5 times 6 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> area. The active integrated antenna demonstrates stable oscillations and excellent radiation patterns at X-band design frequencies. When biased using a single 1.5 volt battery connected between the source and drain and with the gate terminal open, the antenna effective isotropic radiated power (EIRP) and direct current (DC)-to-radiated radio frequency (RF) conversion efficiency are +11.2 dBm and 10.5%, respectively. The radiated power level and directivity are +4.5 dBm and 6.7 dBi, respectively. The phase noise at 100 kHz offset from the carrier is -87.5 dBc/Hz, which is a notable improvement over existing AIA designs. The AIA features compact size and simple geometry, yet provides radiated power levels and radiation efficiencies that are comparable to values typically obtained using circuits that occupy larger areas, and use thicker substrates with much lower dielectric constant values.

Novel Utilization of the Dielectric Resonator Antenna as an Oscillator Load

For the first time, the idea of using the dielectric resonator antenna (DRA) as an oscillator load, named as DRAO, is presented in this paper. Unlike the conventional dielectric resonator oscillator (DRO), where the DR was merely used as a resonator, the DR here serves as both the radiating and oscillating loads. In addition, a compact tri-function hollow DR that incorporates the packaging function to the above dual function is demonstrated. The design procedures of the dual- and tri-function DRAOs are discussed. For demonstration, the DRAOs are designed at 1.85 GHz, which is used in the popular personal communications system (PCS). The return losses, input impedances, antenna gains, signal spectrums, phase noise, and radiation patterns of the two DRAOs are presented. It is shown that the loaded QL factor of the DRA can be increased by internally embedding a compact metallic cavity to the DR. It is found that with a higher loaded QL factor, the phase noise of the antenna oscillator using the hollow DRA (tri-function DRAO) is better than that using a solid DRA (dual-function DRAO).

A Convex Optimization Method for Constrained Beam- Steering in Planar (2-D) Coupled Oscillator Antenna Arrays

Constrained beam steering in planar coupled oscillator arrays is presented as a convex optimization problem extending previous works applied in linear arrays. Maximum level constraints are introduced in the array factor by perturbing both the amplitudes and the phases of the array elements. The steady state of the array is included in the optimization problem as a linear constraint. After an optimized solution is found its stability is examined. Design examples that demonstrate the validity of the method are presented.

Pattern Nulling in Coupled Oscillator Antenna Arrays

An optimization method is presented for constrained beam steering with null formation in linear coupled oscillator arrays. The method is based on a perturbation model of the far field of the array that includes both amplitude and phase perturbations, to accommodate prescribed nulls. Moreover, it takes into account the array nonlinear dynamics through a first-order approximation model of the array steady state. The optimization results are verified by harmonic balance simulations. Also, the stability of the optimized solutions is examined by perturbing the steady state solution and is verified with envelope transient. Design examples are used to demonstrate the validity and limitations of the proposed method

W-Band Active Integrated Antenna Oscillator Based on Full-Wave Design Methodology and 0.1- m Gate InP-Based HEMTs

An active integrated antenna (AIA) oscillator consisting of an active circuit and planar antenna on the same substrate can be used as a high-performance, low-cost, small component for millimeter-to-sub-millimeter wave applications. We describe a highly extended, finite-difference-time-domain full-wave analysis method for designing AIA circuits precisely. It treats active devices as distributed elements. Using this method and 0.1-μm-gate InP-based HEMTs, we fabricated W-band AIA oscillators with an oscillation frequency of 111 GHz.

Active integrated antenna using T‐shaped microstip‐line‐fed slot antenna

AbstractAn active integrated antenna (AIA), which consists of a T‐shaped microstrip‐line‐fed slot antenna, is proposed. Since the designed antenna has an electromagnetically coupled feedback loop, it can easily solve the problem of DC isolation between ports of the amplifier. The fabricated parallel feedback antenna oscillator shows stable oscillation at a frequency of 10.05 GHz. The measured EIRP is 37.79 mW, and the cross‐polarization levels are at least −15‐dB lower than those of co‐polarization for all directions. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 367–370, 2006; Published online in Wiley InterScience (www. interscience.wiley.com). DOI 10.1002/mop.21351

Active Integrated Antenna Techniques for Beam Control

Active integrated antenna techniques have high potential for giving smaller size, lighter weight, lower cost and higher efficiency, in particular to millimeter-wave circuit-antenna systems. This paper gives a review of active integrated antenna techniques with emphasis on beam steering and retrodirective antenna arrays. Various beam steering operations of integrated antenna oscillator arrays using locking phenomena are presented. Beam steering arrays of such type have the feature that phase shifters are not necessary in the arrays. Arrays with higher harmonic output radiation can enlarge the beam steering range. Arrays of locked active antennas which operate as self-oscillating mixers can be beam controllable receiving antennas.

Active integrated antenna using T-shaped microstrip-line-fed slot antenna

An active integrated antenna (AIA) which consists of a T-shaped microstrip-line-fed slot antenna is proposed. Since the designed antenna has an electromagnetically coupled feedback loop, it can easily solve the problem of DC isolation between a radiator and amplifier. The fabricated parallel-feedback antenna oscillator shows stable oscillation at a frequency of 10.05 GHz. The measured effective isotropic radiated power (EIRP) is 37.79 mW, and the cross-polarization levels are at least −15-dB lower than those of co-polarization for all directions. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 46: 538–540, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21041

Hybrid active integrated antenna arrays with a 23‐GHz MMIC oscillator

AbstractAn ultrasmall active integrated antenna 2.5 cm square was fabricated by combining an MMIC oscillator and planar slot antennas. The design of array antennas by simulation and analysis of their injection locking characteristics are presented. Beam steering and the effect of packaging are considered in the measurement, and the effect of the metal reflector plate behind the array antenna is studied. A small active integrated antenna is placed at the focal point of a parabolic antenna. Its operation as a receiving integrated antenna with a self‐oscillating mixer for communication satellite is confirmed. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 86(11): 46–56, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10115