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11.
Near-field scanner for the detection of passive intermodulation sources in base station antennas 总被引:1,自引:0,他引:1
Hienonen S. Golikov V. Vainikainen P. Raisanen A.V. 《Electromagnetic Compatibility, IEEE Transactions on》2004,46(4):661-667
Passive intermodulation (PIM) distortion is a challenging problem in the design and manufacturing of base station antennas. Small nonlinearities, typically in junctions, may cause a distortion signal that interferes with the receiver even with a level of -155 dBc in a GSM900 system. The PIM level specification of an outdoor base station antenna is difficult to achieve and the sources of PIM generation are laborious to track down. In this paper, a near-field measurement method is presented to localize and investigate passive intermodulation sources in antennas and open transmission lines. The principle of the PIM near-field measurement is otherwise the same as in a common reactive near-field measurement, but instead of measuring the signal at the input frequency, the signal amplitude and phase at the PIM frequency of interest are acquired. The constructed measurement system is capable of measuring PIM signal levels down to -110 dBm with 2/spl times/43 dBm transmit power in the GSM900 frequency band. As demonstration measurements, PIM sources in a two-element base station antenna and in a microstrip line are localized. 相似文献
12.
Tuovinen J. Hirvonen T.M. Raisanen A.V. 《Antennas and Propagation, IEEE Transactions on》1992,40(6):613-619
At millimeter-waves quasi-optical systems are commonly designed based on the Gaussian beam and thin lens approximation. The accuracy of the Gaussian beam and thin lens approximation was studied in the case of a corrugated horn and a thick Teflon lens (focal length to lens diameter ratio f /D =1.2) combination at 87 GHz. A special near-field measurement system was constructed. A large disagreement between the measured and theoretical values with the approximative method was obtained. The measurements showed that the thin lens approximation breaks down when the distance from the input beam waist to the lens is less than 1.5 D . Theoretical values obtained with a thick lens model based on ray tracing and use of exact Huygens' aperture integration principle agree well with the measurements 相似文献
13.
Raisanen A.V. 《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》1992,80(11):1842-1852
Theory and tools for analysis and design of millimeter- and submillimeter-wave multipliers are discussed. Experimental work is reviewed. The Schottky diode model at submillimeter frequencies, use of Schottky multiplier chains versus direct higher-order multipliers, and the effect of cooling on Schottky diode multipliers are discussed. Alternative diodes such as the high electron mobility varactor (HEMV), the barrier-intrinsic-n+ diode (BIN), the barrier-n-n+ diode (BNN), the quantum well diode (QWD), and the single barrier varactor (SBV) are discussed, with attention given to their potential submillimeter frequency multipliers 相似文献
14.
Saily J. Ala-Laurinaho J. Hakli J. Tuovinen J. Lehto A. Raisanen A.V. 《Electronics letters》2000,36(2):111-112
The quiet-zone field test results of a submillimetre-wave compact antenna test range (CATR) based on a 60 cm diameter hologram are presented. The instrumentation setup based on a dedicated millimetre-wave vector network analyser is also briefly described. The presented test results at 310 GHz show the potential of the hologram CATR for submillimetre-wave antenna testing 相似文献
15.
Hakli J. Koskinen T. Lonnqvist A. Saily J. Viikari V. Mallat J. Ala-Laurinaho J. Tuovinen J. Raisanen A.V. 《Antennas and Propagation, IEEE Transactions on》2005,53(10):3142-3150
Hologram-based compact antenna test range (CATR) is a potential method for testing large antennas at submillimeter wavelengths. This paper describes testing of a 1.5-m single offset parabolic reflector antenna with a 3-m-diameter hologram-based CATR. This is the first time such a measurement is carried out at submillimeter wavelengths. The antenna tests were done in a CATR that was specifically designed and constructed for these tests. The measured radiation pattern at the frequency of 322 GHz is presented. The measured pattern corresponds reasonably well to the simulated pattern of the antenna. The effect of the quiet-zone field nonidealities on the measurement results and the reasons for the discrepancies in the measured antenna beam are discussed. 相似文献
16.
Lonnqvist A. Koskinen T. Hakli J. Saily J. Ala-Laurinaho J. Mallat J. Viikari V. Tuovinen J. Raisanen A.V. 《Antennas and Propagation, IEEE Transactions on》2005,53(10):3151-3159
A hologram-based compact antenna test range (CATR) is being developed to overcome challenges met in antenna testing at submillimeter wavelengths. For the first time, this type of CATR has been built for testing of a large reflector antenna at submillimeter wavelengths. The CATR is based on a 3-m computer-generated hologram as the focusing element. This paper discusses the design and the construction of the CATR, and the verification of the CATR operation with quiet-zone tests done for the CATR prior to the antenna testing. Assembly of the CATR, testing of the 1.5-m reflector antenna at 322 GHz, and the disassembly were all done within two months in 2003. The quiet-zone field measurement results are analyzed in this paper. The CATR was concluded to be qualified for antenna testing. The antenna testing is described in a separate paper. 相似文献
17.
I. M. Vitomirov A. Raisanen S. Chang R. E. Viturro L. J. Brillson D. F. Rioux P. D. Kirchner G. D. Pettit J. M. Woodall 《Journal of Electronic Materials》1993,22(1):111-117
Effects of substrate doping and growth method on interface deep level formation and Schottky barrier height were investigated
using low-energy catho doluminescence and soft x-ray photoemission spectroscopy. Our results reveal that for Au/GaAs(100)
contacts Fermi level (EF) stabilization energy shows little sensitivity to either substrate growth technique or the type of doping, and Iles in the
0.37 to 0.47 eV range above the valence band maximum (Ev). In contrast, the EF position at Al/GaAs(100) interfaces is highly sensitive to substrate growth method for n-type GaAs, but shows no significant
difference between the epitaxial and melt-grown p-type GaAs. Furthermore, for a specific substrate dopant type and growth
method, gold and aluminum produce barrier heights which differ by 0.05 to 0.50 eV, depending upon the substrate growth and
dopant properties. Cathodoluminescence results demonstrate that discrete surface and interface states responsible for EF stabilization at these metal/GaAs junctions are highly sensitive to the substrate growth technique, as well as to the specific
metal contact. This work emphasizes that both substrate crystalline and electronic properties, as well as the adatom-specific
interface chemistry are crucial for the electrostatic barrier height formation at metal/GaAs contacts. 相似文献
18.
19.
A. Raisanen L. J. Brillson R. S. Goldman K. L. Kavanagh H. Wieder 《Journal of Electronic Materials》1994,23(9):929-933
We have performed luminescence experiments on In0.08Ga0.92As/GaAs heterointerfaces to explore the energy distribution of deep level states in the bandgap for two cases: (1) unrelaxed, pseudomorphic In0.08Ga0.92As films (200Å thick), which have few if any dislocations at the interface, and (2) partially relaxed In0.08Ga0.92As films (1000Å thick) which are expected to have a substantial interfacial dislocation density. A combined photoluminescence and cathodoluminescence technique is used which allows us to profile the sample luminescence through the buried interface region. Our results show the existence of deep level luminescent features characteristic of the GaAs substrate and features common to In0.08Ga0.92As and GaAs, as well as the existence of a deep level feature near 1 eV photon energy which undergoes a shift in energy depending upon the degree of strain relaxation in the In0.08Ga0.92As film. In addition, a deep level feature near 0.83 eV becomes prominent only in In0.08Ga0.92As films which have relaxed, and thus contain misfit dislocations at the interface. These deep level differences may be due to bandgap states associated with the intrinsic dislocation structure, impurities segregated at the dislocation, or bulk point defects, or threading dislocations generated during the strain relaxation. Previous work has determined that a deep level state 0.7 eV above the valence band edge would account for the electrical behavior of relaxed In0.08Ga0.92As/GaAs interfaces, which is in good agreement with the range of deep level transitions near 0.8 eV photon energy which we observe. These measurements suggest that photo- and cathodoluminescence measurements of deep level emission in these III-V semiconductors can provide a useful indicator of electrically active defect densities associated with misfit dislocations. 相似文献
20.
A compact antenna test range based on a hologram 总被引:2,自引:0,他引:2
Hirvonen T. Ala-Laurinaho J.P.S. Tuovinen J. Raisanen A.V. 《Antennas and Propagation, IEEE Transactions on》1997,45(8):1270-1276
The application of conventional reflector-type compact antenna test ranges (CATRs) becomes increasingly difficult above 100 GHz. The main problems are the tight surface accuracy requirements for the reflectors and, therefore, the high manufacturing costs. These problems can be overcome by the use of a hologram type of compact range in which a planar hologram structure is used as a collimating element. This idea is described and its performance is studied with theoretical analyses and measurements at 119 GHz 相似文献