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This paper presents a calibration method used to compensate channel amplitude and phase mismatch of the retrodirective antenna array for microwave power transmission. The calibration algorithm of N elements array antenna involves transmission of N time multiplexed orthogonal encoded signals. The received signals are coherently detected, accumulated in vector forms, and a set of correction factors...
When antenna arrays are placed on platforms, antenna patterns and antenna characteristics change significantly. Calibration of antenna arrays becomes an inevitable and important task to correct the imperfections due to the antenna surroundings. In this paper, a time-gating method is proposed to calibrate the direction finding antenna array on a UH-60 helicopter on ground. The helicopter is placed...
Channel reciprocity is regarded as one of the most important advantages of TDD systems. However, the uplink (UL) and downlink (DL) channels are not actually reciprocal because of different characteristics of transmitters (TXs) and receivers (RXs). When the antenna elements are placed with large distance, the Radio Frequency (RF) gain mismatch of TXs and RXs is the dominant un-reciprocal factor, but...
In this paper the effect of on-air-combining on the signal quality in distributed transmitter systems like active antennas is described. Active antennas containing a multitude of parallel, independent transmitter chains are emerging in the mobile communication base station market. Due to the independent transmitter chains, each signal is subject to different distortions by the various transmitter...
A low-cost ultrawideband (UWB), 1.926-4.069 GHz, phased array radar system is developed that requires only one exciter and digital receiver that is time-division-multiplexed (TDM) across 8 receive elements and 13 transmit elements, synthesizing a fully populated 2.24 m long (λ/2 element-to-element spacing) linear phased array. A 2.24 m linear phased array with a 3 GHz center frequency would require...
The Uninhabited Airborne Vehicle Synthetic Aperture Radar (UAVSAR) is an L-band (1.2-1.3 GHz) repeat pass, interferometric synthetic aperture radar (InSAR) used for Earth science applications. Using complex radar images collected during separate passes on time scales of hours to years, changes in surface topography can be measured. Due to variations in aircraft attitude between passes, antenna beam...
Coherent arraying of transmitting antenna signals at a distant spacecraft provides an effective gain proportional to N2, where N is the number of antennas in the array. This technology is currently being developed for NASA's Deep Space Network (DSN) to provide greater range and data throughput for future NASA missions, including manned missions to Mars and exploratory missions to the outer planets,...
This paper presents a procedure used to calibrate a multi-beam antenna array to compensate for channel amplitude and phase mismatch. The multi-beam smart antenna is based on Butler matrix. The calibration algorithm of N elements array antenna involves transmission of N time multiplexed orthogonal encoded signals. The received signals are coherently detected, accumulated in vector forms, and a set...
An important idea for improving the practical performance of direction finding (DF) systems involves the use of calibration tables. These are generally based on experimental measurements of systemic errors obtained using a known signal to illuminate the antenna. However, the accuracy of the calibration data, and therefore that of the system, is affected by various error mechanisms. This paper uses...
Smart antenna technology can significantly improve the coverage radius, increase channel capacity, reduce transmitting power as well as overcome multipath effects by adaptive beamforming. The performance of digital beamforming is greatly affected by the amplitude-phase inconsistency among the channels. We propose a method of calibrating amplitude-phase errors of RF channels of DBF transmitting antenna...
This paper briefly describes pros and cons of using arrays of small antennas instead of large single dish antennas for spacecraft telemetry, command, and tracking (TT&C) - communications and navigation (C&N) - and science support that the deep space network (DSN) normally provides. It considers functionality and performance aspects, mainly for TT&C, though it also considers science. It...
A new permutation method for ICA (independent component analysis) separated signal blocks is presented. The proposed method utilizes the associativity in column vectors of estimated mixing matrix and tracking filter. It has advantages of not requiring array calibration, efficient computation, and real time updatability. Furthermore, it is shown, by an experiment using radio wave signals, that the...
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