Active antenna

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

Lightning-proof GNSS active antenna

Abstract: The invention discloses a lightning-proof GNSS active antenna and relates to a GNSS receiving antenna which is applicable in navigation, positioning and time and frequency standards. The problem to be solved by the invention is to provide a high-reliability GNSS active antenna which avoids using a lightning arrester, effectively prevents damages caused by lightning stroke and has a lightning-proof capability meeting the requirements of communication industrial standards of 'Specifications for Engineering Design of Lightning Over-Voltage Protection for Communication Bureaus(Stations )' YD/T5098-2001. The lightning-proof GNSS active antenna is characterized in that: a GNSS passive antenna, a GNSS low noise amplification module, a radio-frequency cable, a lightning-protection module and a bolt-fixed sealed type needle radio frequency connector are connected in turn and accommodated in a sealed shell which consists of a radar cover and a mounting chassis; and the modularized and layered structure design is adopted, so that a production process is simplified, the production efficiency is improved and the production cost is reduced. The lightning-proof GNSS active antenna effectively prevents the active antenna being damaged by the lightning stroke, avoids using the lightning arrester, saves the system cost and simplifies the project installation.

High-impedance amplifier for a novel 14 cm short AM/FM automotive active antenna

Abstract: The design of an ultra short capacitive coupled helical AM/FM active automotive antenna with a length of only 14 cm (5.6") is investigated and its performance is presented. The antenna element produces very sharp resonances and is therefore difficult to use for broadband radio reception. The proposed high impedance amplifier concept flattens the frequency response of the very short resonant antenna, while maintaining a low noise level and a good linearity. The design has been realized and the measurements show that the new 14 cm active antenna has comparable sensitivity with 40 cm (15.8") long active monopole antennas. Field measurements indicate good performance in comparison to common passive rod antennas of 90 cm (35.4") length, both in AM and FM range.

Frequency Domain Equalization for Single and Multiuser Generalized Spatial Modulation Systems in Time Dispersive Channels

Abstract: In this letter, a low-complexity iterative detector with frequency domain equalization is proposed for generalized spatial modulation (GSM) aided single carrier (SC) transmissions operating in frequency selective channels. The detector comprises three main separate tasks namely, multiple-input multiple-output (MIMO) equalization, active antenna detection per user and symbol wise demodulation. This approach makes the detector suitable for a broad range of MIMO configurations, which includes single-user and multiuser scenarios, as well as arbitrary signal constellations. Simulation results show that the receiver can cope with the intersymbol interference induced by severe time dispersive channels and operate in difficult underdetermined scenarios.

밀리미터파 대역 제2고조파 발진기 결합계의 위상차 배열 동작

Abstract: A new approach to the active phased arrays for the second harmonic generation is presented. Phase variation between the second harmonic oscillators by the mutual synchronization is analyzed theoretically. In this coupling, the active antenna consists of the FET oscillator which plays two roles in fundamental oscillation and frequency multiplying, and the patch antenna resonated at the second harmonic frequency. The radiated second harmonic wave was scanned by varying the free-running oscillation frequencies of the active antennas. In the experiment using the 2-elements array and the 4-elements array, the radiated beam of the second harmonic wave was scanned more widely compared with the case of the fundamental wave radiation.

Backup WiFi light carrier wireless switching system

Abstract: The invention discloses a backup WiFi light carrier wireless switching system. The system comprises: a near-end unit; a far-end node, which is connected with the near-end unit through an optical fiber link; and an active antenna, which is electrically connected with the far-end node. The near-end unit consists of a controller, a main access point, a backup access point, an RF switch, a transmit-receive separating unit and a first photoelectric/electric-photo conversion unit. The far-end unit includes: a second photoelectric/ electric-photo conversion unit, which is electrically connected with the first photoelectric/ electric-photo conversion unit of the near-end unit through the optical fiber link; a power amplifier; a low noise amplifier; and a duplexer, which is simultaneously connected with the power amplifier and the low noise amplifier as well as is connected with the active antenna; besides, the power amplifier and the low noise amplifier are simultaneously connected with the second photoelectric/ electric-photo conversion unit. The controller controls the RF switch to be communicated with the main access point and be disconnected with the backup access point, so that the WiFi radio-frequency signal of the main access point can be transmitted to the far-end node through the optical fiber link.