Active antenna

About: Active antenna is a research topic. Over the lifetime, 2246 publications have been published within this topic receiving 26493 citations.

Radar imaging system having negative refractive index

Abstract: The invention discloses a radar imaging system having a negative refractive index. The radar imaging system comprises a radar receiving antenna and radio frequency unit made of a lefthanded medium material, a radar emission antenna and radio frequency unit, a control center, an emission base band processing unit, an image acquisition unit for acquiring echo data, and an image processing unit for imaging the acquired echo data. In the radar imaging system having the negative refractive index, a lefthanded medium having the negative refractive index is used in a receiving antenna of the radar imaging system, so an active antenna can be imaged at a position near a target; a distance from an image plane where an image antenna is positioned to the target can be controlled by adjusting an equivalent dielectric constant and an equivalent magnetic conductivity of the lefthanded medium, so the imaging resolution is adjusted; theoretically, the resolution can be accurate to a point, so that the problem of constraint of the length of a synthesized aperture on the imaging resolution can be radically solved, namely an image having high resolution can be acquired under the condition of extremely tiny length of the synthesized aperture; therefore, an image having high resolution can be acquired in real time in a strip-type imaging mode.

Bidirectional Field Compensated Active Antenna

Abstract: A bidirectional active antenna for vehicular and mobile applications is presented. Via a shielding electrode inserted between the antenna electrode and the ground electrode active field compensation is performed and by this way the electrical antenna height is increased substantially. This allows the realization of flat conformal antennas for vehicular and mobile applications.

Link adaptation for spatial multiplexing MIMO systems

Abstract: A fast near-optimal transmission scheme selection algorithm for multiple-input multiple-output (MIMO) systems using spatial multiplexing and linear detection is proposed and analyzed. The algorithm selects a transmit antenna subset such that applying available coding and modulation (CM) modes on each spatially multiplexed substream optimises the throughput under constraints on maximum expected bit error rate (BER) assuming straightforward linear detection. Comparing the performance of the system applying proposed and optimal selection algorithms nearly no degradation is observed with the former. The simulation results also show that a low-rate feedback specifying the active antennas and CM mode per each active antenna enables high spectral efficiency and reliability even for straightforward linear detection.

Shirokov active transceiving antenna

Abstract: FIELD: antennas.SUBSTANCE: active transceiving antenna belongs to antenna engineering and can be used in radio communication systems, radio navigation systems, radars. Especially useful application of the active transceiving antenna can be when building antenna arrays. Novelty of the active transceiving antenna is implementation of its operation in the mode of reception and transmission simultaneously. Active transceiving antenna consists of a field-effect transistor, a blocking capacitor and the microstrip antenna itself on a dielectric substrate with a shielding plate. Microstrip antenna has leads (branches), which through holes in the shielding plate are connected to the field-effect transistor in various circuit configurations and with a high-frequency connector of feeding and recording radio-frequency signals. Leads of the microstrip antenna connection with the field transistor form a positive feedback, which provides regenerative amplification of signals. Besides, this amplification is carried out both for received by the antenna signals and by recording of already amplified signals at the high-frequency connector of the active antenna, and for signals transmitted to this high-frequency connector and then amplified by the regenerative amplifier with subsequent radiation of electromagnetic waves of the microstrip antenna itself.EFFECT: to eliminate self-excitation of the circuit it is necessary either to select parameters of the field-effect transistor and the position of the microstrip antenna leads, or to supply external control voltage to the field-effect transistor in various circuit configurations.1 cl

Channel abnormality detecting and repairing method and device for active antenna

Abstract: The present disclosure provides a method and device for detecting and repairing a channel anomaly of an active antenna, and the method includes: an operation state of a transmission channel or a reception channel is determined by analyzing in real time data of a feedback coupling channel or data of the reception channel, if the operation state is anomalous, an anomaly protection is performed and an alarm is reported; a level of the alarm and a reason causing the alarm are determined, if data of the transmission/reception channel are anomalous and the anomaly protection is performed, a current antenna beam forming parameter is stored and the antenna beam forming parameter is set to zero; after the alarm has been eliminated, a stored valid antenna beam forming parameter is set to a valid value; and if a transmission/reception analog channel operates anomalously and the anomaly protection is performed, the antenna beam forming parameter is re-acquired and an acquired valid antenna beam forming parameter is configured. The present disclosure can detect states of multiple transmission/reception channels of an active antenna without an extra calibration channel, thus reducing the design cost of a system.