有源微带天线阵列的实验研究

本文提出了一种混和集成型有源阵列天线结构，并对这一结构进行了空间功率合成的实验研究。功率源采用微带型振荡电路；天线采用矩形微带贴片阵列，二者通过背馈相连。贴片天线阵间的互耦使振荡单元间实现注入镇定，各单元的辐射功率在空间实现合成。在Ｘ波段成功地实现了四单元有源阵列的互锁和空间功率合成。本文报导了实验结果并给出了一些有意义的结论     

Modified rectangular patches for self-oscillating active-antennaapplications

Two modifications to a rectangular-patch antenna, suitable for the integration of active devices, are presented. In the first modification, the impedance inverter was placed in the rectangular opening formed by removing the central part of the patch. This modification allows optimal matching of the active device by changing the position, width, and length of the impedance-line transformer. An oscillating antenna, using this modified patch and a Gunn diode, showed a high EIRP, higher spectral purity, and substantially lower cross-polarization levels, in comparison with the reference active antenna with an unmodified patch. Because of the higher overall Q, this modification is recommended for active-antenna applications with active devices that have a narrower negative-resistance bandwidth. In the second modification, an active device (Gunn diode) was integrated directly into a rectangular opening inside the patch, without the use of a line transformer. This reduced the overall Q of the antenna, thus allowing wide-band frequency tuning by changing the bias voltage. A clear spectrum, with no spurious components of the free-running oscillating antenna, was observed. Radiation patterns in the E and H planes were measured. Low levels of cross-polarization, as for the first modification, were obtained. Injection-locking properties were investigated throughout the tuning range. A relatively wide locking range, with a good locking gain, was achieved. Such a miniaturized wide-band VCO antenna is applicable for integration in injection-locked active arrays, and spatial power combiners     

Compact amplifier integration in square patch antenna

A packaged microwave bipolar transistor has been integrated directly onto a rectangular microstrip patch to obtain extra power gain and to reduce power losses. The radiating element geometry has been modified to incorporate the active devices. This active antenna uses a small number of components and takes the same place as a passive antenna. An extra gain of 8 dB is obtained at 1.68 GHz.<>     

Broadband electronically tunable planar active radiating elementsand spatial power combiners using notch antennas

A Gunn device has been integrated with two types of active planar notch antennas. The first types uses a coplanar waveguide (CPW) resonator an a stepped-notched antenna with bias tuning to achieve a bandwidth of 275 MHz centered at 9.33 GHz with a power output of 14.2±1.5 dBm. The second type uses a CPW resonator with a varactor for frequency tuning to achieve a bandwidth of over 1.3 GHz centered at 9.6 GHz with a power output of 14.5±0.8 dBm. This is equivalent to over 14% electronic tuning bandwidth. Both configurations exhibit a very clean and stable output signal. A theoretical circuit model was developed to facilitate the design. The model agrees well with experimental results. Injection-locking experiments on the second configuration show a locking gain of 30 dB with a locking bandwidth of 30 MHz at 10.2 GHz. Power combining experiments of two-varactor-tuned CPW active notch antenna elements in a broadside configuration have achieved well over 70% combining efficiency throughout the wide tuning range. The circuits have advantages of small size, low cost, and excellent performance     

Analysis and design of aperture-coupled microstrip patch antennasand arrays fed by dielectric image line

This paper presents the analysis and design of aperture-coupled microstrip patch antennas and arrays fed by an dielectric image line. A theory based on the cavity model of the microstrip patch antenna and the change in the modal voltage of the image line at the aperture was developed to analyze the single element aperture-coupled microstrip patch antenna. The theory developed was combined with the array theory to design linear traveling wave arrays at X-band and Ka-band frequencies. The required taper in the excitations of the individual patches of the array was achieved by varying the aperture dimensions. Experiments show very good results for the antennas and the arrays     

Active Frequency-Tune Beam-Scanning Leaky-Wave Antenna Arrays

X-band active beam-scanning leaky-wave antenna arrays, including 1 × 1,1 × 2 and 1 × 4 prototypes, have been demonstrated. These antennas integrated one or several microstrip leaky-wave antenna elements with a single varactor-tuned HEMT VCO as an active source. Measured results on experimental antennas indicate that the beam scanning angle of the 1 × 1 antenna close to 40° can be achieved and the scanning range of 1 × 2 and 1 × 4 antenna arrays are both close to 32°. Furthermore, reflected wave due to the open end of each leaky-wave antenna element has been suppressed by the symmetric configuration of this antenna array and the antenna efficiency increases. When comparing with the measured radiation pattern of the single element antenna, we found that the 1 × 2 and 1 × 4 antenna arrays can effectively suppress the reflected power by more than 5.5 dB and 10.5 dB, respectively, at 10.2GHz. The power gain are more than 2 dB and 3.16 dB higher than the single element antenna with a measured EIRP of 18.67 dBm.     

Novel FET active patch antenna

A novel dual-FET active patch antenna element for quasi-optical power combining arrays is described. The circuit uses two FETs which symmetrically load a split patch antenna. The push-pull operation of the devices decreases H-plane crosspolarisation dramatically. A power output of 47 mW was achieved at 8.1 GHz.<>     

A periodic second harmonic spatial power combining oscillator

The authors present a periodic second-harmonic spatial power combining oscillator. The power combining is achieved by phase locking the oscillators at the fundamental frequency and combining the second-harmonic power in space through an array of microstrip patch antennas. The effect of moding and multiple device-circuit interaction is investigated. This circuit is planar, and therefore simplifies the design of monolithic circuits, X-band Gunn diodes are used for the purpose of demonstration     

Active inverted stripline circular patch antennas for spatial powercombining

An active antenna configuration is proposed for spatial-power-combining applications. The active patch antenna uses an inverted stripline topology to take advantage of several features. These features include avoiding drilling through the circuit substrate to insert the diode and the use of air within the resonant cavity to reduce loss. The inverted substrate serves as a radome for hermetic sealing. The active antenna and housing can be fabricated in modular form for reduced cost and easy replaceability of devices. The active inverted stripline patch antenna exhibits a much cleaner spectrum and greater stability than previously reported active antennas. The fixture serves as a ground plane, heat sink, and support in an active planar array or as a mirror in a quasi-optical power-combining resonator. A single active antenna operating at 9.23 GHz exhibited a 16-MHz locking bandwidth at 30-dB locking gain. Power-combining efficiencies of over 89% have been demonstrated for a four-element square array that maintained injection-locking and power-combining over a 60-MHz bias tuned bandwidth. Similarly, a four-element diamond array showed over 86% combining efficiency and 50-MHz bias tuned bandwidth. Beam steering was demonstrated by varying bias voltage to the individual antenna elements of the square array     

Polarisation agile active microstrip patch arrays

Two three-element polarisation-agile active microstrip patch arrays have been developed. The radiating elements are square patches each with two transistors mounted on adjacent edges. The patches radiate orthogonal modes, the relative phase of which can be varied. Radiation patterns show good agreement with predictions from theory, in both linear and circular polarisation, and no grating lobes were observed     

Novel low-cost beam-steering techniques using microstrip patchantenna arrays fed by dielectric image lines

This paper presents novel low-cost beam-steering techniques using microstrip patch antenna arrays fed by dielectric image lines (DILs). Two approaches are designed and used. The first, DILs without reflector plate, are used for feeding microstrip patch antenna arrays. Antenna array radiation beams are scanned when the operating frequency sweeps. The second, a dielectric image line with a movable reflector plate (DILWRP), is developed. The beam direction of the antenna array is controlled and steered by changing the perturbation distance between DIL and movable reflector plate at a given operating frequency. Both types of patch antenna array structures are simple, low cost, easily fabricated, stable, and reliable. Eight-element patch antenna arrays fed by DIL and DILWRP have been designed, fabricated, and tested. Experiments show good performance and results. Measurement results of scanning angles agree well with theoretical predictions     

Oscillator noise reduction in cavity-backed active microstrip patchantenna

A rectangular cavity-backed active microstrip patch antenna has been investigated Experimental results show that 25 dB oscillator noise reduction can be achieved for the active patch antenna at a carrier frequency of 4.1 GHz and an offset frequency of 8 kHz by using a rectangular cavity     

Radiating and scattering analyses of a slot-coupled patch antennaloaded with a MESFET oscillator

In this paper, radiating and scattering analyses of a slot-coupled patch antenna loaded with a MESFET oscillator at free-running and injection-locked states are presented. This arrangement is a basic module of an injection-locked active array. With a small injection signal applied directly to the oscillator in a transmission-type mode or indirectly through a patch antenna to the oscillator in a reflection-type mode, the oscillator loaded antenna then becomes an injection-locked active antenna (ILAA) within the locking range. Simulation results yield the oscillating frequency and radiating power at the free-running state and the locking range and radiating power at the injection-locked state. Both radiating and scattering analyses are performed in a unified approach for the transmission-type and reflection-type operation modes of ILAA. Experiments show the validity of the developed theoretical analyses. These results can be applied in the ILAA array design     

Méthodes d’analyse et de synthèse de quelques “ microantennes” à large bande en mode quasi transversal électromagnétique

The transmission line model has been utilized to determine the input impedance, the bandwidth, the radiation patterns and the mutual impedance of several microstrip antennas such as the arbitrary shape patch antennas and the wideband flat dipole which is an hybrid radiating source. We suppose that the dominant mode of propagation is the quasiTem one having negligible variation of fields in the transverse direction. Nevertheless a general scattering problem of an arbitrary shaped tridimensional antenna solved by moments method and the finite difference approach applied to integral equations has explained the very large bandwidth microstrip antenna behaviour. The wideband flat dipole has been used in flat arrays, with more than several hundred of such elements, and in microstrip phased arrays with beam steering in a large angular sector.     

Push-pull power amplifier integrated with microstrip leaky-waveantenna

An X-band active integrated antenna push-pull power amplifier is presented that uses a dual feed microstrip leaky-wave antenna for both out-of-phase power combining and second harmonic tuning. This novel structure results in a compact and high efficiency power amplifier design. At the operating frequency of 8.7 GHz. A maximum measured PAE of 54% at an output power of 38.1 dBm has been achieved     

Microstrip Yagi array antenna for mobile satellite vehicleapplication

A novel antenna structure formed by combining the Yagi-Uda array concept and the microstrip radiator technique is discussed. This antenna, called the microstrip Yagi array, has been developed for the mobile satellite (MSAT) system as a low-profile, low-cost, and mechanically steered medium-gain land-vehicle antenna. With the antenna's active patches (driven elements) and parasitic patches (reflector and director elements) located on the same horizontal plane, the main beam of the array can be tilted, by the effect of mutual coupling, in the elevation direction providing optimal coverage for users in the continental United States. Because the parasitic patches are not connected to any of the lossy RF power distributing circuit the antenna is an efficient radiating system. With the complete monopulse beamforming and power distributing circuits etched on a single thin stripline board underneath the microstrip Yagi array, the overall L -band antenna system has achieved a very low profile for vehicle rooftop mounting, as well as a low manufacturing cost. Experimental results demonstrate the performance of this antenna     

共口径波束可控双缝隙耦合微带天线阵设计

针对波束倾角可控天线的小型化和低成本,设计了宽频带双缝隙耦合矩形微带天线单元,组成1×8元线阵,采用2套基于Wilkinson不等功分器的馈电网络实现切比雪夫的幅度分布。具有不同相位差的2套馈电网络,通过不同的缝隙耦合对同一微带单元口径面馈电,分别形成了2种倾角的波束。仿真结果表明,共口径双缝隙耦合微带天线阵实现了90°和75°两种波束倾角的可控切换,是一种体积小、造价低的方向图可重构天线。     

Evaluation of gain enhancement in improved size microstrip antenna arrays for millimetre-wave applications

A number of microstrip antenna arrays have been designed based on the improved size patch elements with different substrate heights to evaluate the gain enhancement in practical measurements. Initially, microstrip patch antenna arrays (MPAAs) have been designed, analysed and tested at 10 GHz frequency and then the optimised high gain (∼21 dBi) array is fabricated and tested at 60 GHz-band frequencies. It has been found that the loss emergence due to the long feeding transmission line (TL) network severely degrades the antenna gain in large MPAAs on the thicker substrates. However, the gain can be significantly enhanced in large MPAAs by employing relatively thinner substrate but it shrinks the return loss (S11) bandwidth (BW) and increases the side lob level (SLL).     

Radial cavity-fed spatial power combiner with retrodirective array behavior

This paper discusses the design and operational properties of a circular array of slot coupled active GaAs metal-semiconductor field-effect transistor (MESFET) rectangular microstrip patch antennas arranged for quasioptical power combining at X band. The active antenna radiating elements are injection locked by slot coupling to a radial cavity waveguide. Spatial power combining efficiency of 75% and dc to radio frequency (RF) conversion efficiency of 10% at 28 dBm EIRP was achieved at 10.38 GHz. Retrodirective action was also demonstrated by using the active elements as self-oscillating mixers pumped at 20.76 GHz.     

Slot-coupled microstrip antenna for broadband circular polarisation

A microstrip antenna with broadband circular polarisation (CP) is presented. The proposed microstrip antenna has a circular patch and is excited by a series microstrip-line-feed configuration through the coupling of a ring slot in the ground plane. The broadband operation is achieved by coupling two CP resonant elements, which are due to the circular patch and the ring slot, respectively. A typical prototype using foam material of thickness 5 mm as the antenna substrate is constructed. Measured results show the 3 dB-axial-ratio bandwidth centred at 2500 MHz is more than 10%.