Active antenna

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

Millimeter Wave systems based on SIMMWICs

Abstract: The use of active integrated antennas (AIAs) as a promising measure of the reduction of millimeter wave systems' costs has been proposed by several authors. Minimization of costs demands integration of the complete millimeter wave front-end on one single chip of minimum dimensions. The demand of minimum dimensions is best met by the active antenna concept, where the generation and/or detection coincides with the transmission and/or reception of a millimeter wave signal. Up to now, millimeter wave systems based on Silicon Monolithic Millimeter Wave Integrated Circuits (SIMMWICs) for the interesting frequency bands above 60 GHz have to employ AIAs due to the behavior of the active elements. In these SIMMWICs an IMPATT diode or a Schottky diode is integrated in the antenna structure. Many sophisticated active antenna designs (based on SIMMWICs and GaAs devices) have been published in recent years. But only a few fully functional demonstration systems were actually built. This is due to some serious design restrictions of AIAs: short-term and long-term stability is supposed to be not sufficient for many system applications; interfacing additional millimeter wave components like mixers is very difficult; and direct modulation is restricted to relatively slow on-off-keying. This paper investigates these problems and develops solutions compatible with the AIA concept. Based on these enhanced front-ends several systems were built. As active devices for signal generation, silicon IMPATT diodes have been employed. For detectors and mixers, silicon Schottky diodes were used.

A broadband sub-array of U-slotted patches for Ku-band active antenna system

Abstract: Satellite mobile communications is a key link in the chain of infrastructure of global communications. A ground mobile antenna with broad frequency band, transiently steerable sharp-beam, miniaturized and low profiled structure, is specifically required for various vehicle systems. As a elemental assemblage of the active array antenna system with spatial power combining, a broadband 4/spl times/2 sub-array is developed in advance by using broadband U-slotted microstrip patch radiators and broadband stripline feed network. The main performances of this sub-array are: 23.24% bandwidth for VSWR/spl les/2:1; the beamwidth is stable within the operating band (12.25-14.50 GHz) with (30-32)/spl deg/ in the E-plane and (15-14)/spl deg/ in the H-plane. The slightly higher side-lobe-level may be suppressed by the factor of the whole array; the cross-polar-level in the E-plane is very good, but deteriorated in the H-plane at the high end of the frequency band, which may be improved by replacing the feed type.

Gain measuring apparatus for active antenna of base station of mobile communication system adopting dual polarized antenna

Abstract: PURPOSE: A gain measuring apparatus is provided to calculate the discharge power of the base station by measuring the receive gain of the active antenna of the base station in an easy manner through the dual polarized antenna. CONSTITUTION: An apparatus comprises a dual polarized antenna(31) supported by a dual polarized antenna support and which has two polarized waves with angle of inclination; an RF signal generator(32) for supplying power of a predetermined size to the dual polarized antenna; an active antenna(41) supported by an active antenna support and which has a dual polarized antenna for receiving radio wave radiated from the dual polarized antenna; a power supply unit(42) for supplying power to the active antenna; a bias-T(43) for supplying power from the power supply unit in the direction toward the terminal connected to the active antenna which requires power supply and transmitting the radio wave received at the active antenna to a spectrum analyzer(44); and the spectrum analyzer for measuring the power of the radio wave received at the active antenna.

PAPR-Limited Precoding in Massive MIMO Systems with Reflect- and Transmit-Array Antennas

Abstract: Conventional hybrid analog-digital architectures for millimeter-wave massive multiple-input multiple-output (MIMO) systems suffer from poor scalability and high implementational costs. The former is caused by the high power loss in the analog network, and the latter is due to the fact that classic MIMO transmission techniques require power amplifiers with high back-offs. This paper proposes a novel hybrid analog-digital architecture which addresses both of these challenges. This architecture implements the analog front-end via a passive reflect- or transmit-array to resolve the scalability issue. To keep the system cost-efficient, a digital precoder is designed whose peak-to-average power ratio (PAPR) on each active antenna is tunable. Using the approximate message passing algorithm, this precoder is implemented with tractable computational complexity. The proposed architecture allows for the use of power amplifiers with low back-offs which reduces the overall radio frequency cost of the system. Numerical results demonstrate that for low PAPRs, significant performance enhancements are achieved compared to the state of the art.