Active Phased Array System Research Articles

CUSTR- A VHF phased array radar for observation of atmospheric dynamics and ionospheric plasma irregularities

A VHF phased array radar for atmospheric dynamics observation is installed at the University of Calcutta, Kolkata. The Calcutta University Stratosphere-Troposphere Radar (CUSTR) operates at 53 MHz with 475 three sub-element Yagi-Uda antenna array. The CUSTR system is a high-power fully active phased array system with a dedicated 2 kW solid-state Transmit-Receiver Module (TRM) attached to each antenna, providing a total peak power of 950 kW with 47.5 kW average power at 5% maximum duty ratio. The system provides electronic beam steering capability to steer the beam 360° in azimuth direction with a maximum off-zenith angle of 40°. The array is configured with 25 sub-arrays and operates either in a combined mode in Doppler Beam Swinging or in Spaced Antenna mode using a multi-channel digital receiver system. The TRM has been designed to provide a very short pulse of 0.5 µs and a long pulse of 128 µs. The system description along with the initial scientific observations such as atmospheric boundary layer, troposphere-lower stratosphere wind measurements along with preliminary wind validation, mesosphere echoes and ionosphere irregularities are presented.

Design of Ka-Band Phased Array Antenna with Calibration Function

In this paper, we have proposed a novel structure of Ka-band based phased array antenna with calibration function. In the design of Ka-band antenna, the active phased array system is adopted and the antenna would work in the dual polarization separation mode. We have given out the schematic diagram for the proposed Ka-band antenna, where the Ka-band antenna is in the form of waveguide slot array antenna, with 96 units in azimuth and 1 unit in distance. Each group of units is driven by a single-channel Transmitter/Receiver (T/R) component, and the whole array contains 192 T/R components in total. The size of the T/R component is 55 mm (length) × 50 mm (width) × 5.8 mm (height), 3 Sub-micro Sub-Miniature Push-on (SSMP) blind sockets and a 21-core low-frequency socket are designed on the two sides of the T/R component. In order to meet the technical specifications of phased array antenna, the Ka-band transceiver component is designed based on Low Temperatrue Co-fired Ceramic (LTCC) technology to achieve miniaturization and lightweight. In our approach, the feed network includes two parts: transceiver network and calibration network. The transceiver network consists of 24 1:8 time-delay power dividers, 12 two-way power dividers and 2 six-way time-delay power dividers. The power supply required by the Ka-band antenna unit is provided to each active component by the power module after Ka band wavelet control distribution. Simulation and measurement results are given in the form of standing wave and scanning capability.

A novel digital transceiver module structure for multi-functional active phased array systems

This paper proposes a transceiver (T/R) module structure for the multi-functional active phased array (APA) systems (including radar and wireless communication systems). The proposed structure uses a full digital interface and applies a GaN supply-modulated power amplifier (SMPA) to improve the power efficiency. In particular, the paper proposes a solution that combines the direct digital synthesis (DDS) with IQ modulation to perform flexibly the functions of phase shifting and amplitude level controlling of the transmitted signals with high resolution for antenna beamforming and scanning. The proposed solution not only eliminates RF attenuator and phase shifter that are commonly used in antenna beamforming but also flexibly configures system functions. The experimental results of designing and manufacturing DDS and IQ modulation parts demonstrate the ability of the proposed structure to generate several common signal types used in radar and communication systems as well as verifies the ability to control the phase and the amplitude level of the transmitted signal.

An Ultra-Wideband Compact TR Module Based on 3-D Packaging

This study presents a novel four-channel tile-type T/R module which achieves excellent performances in ultra-wideband (2–12 GHz) and integrates all circuits in a super-light (25 g) and compact (27.8 × 27.8 × 12 mm3) mechanical structure in active phased array systems. The key advancement of this T/R module was to choose a Ball Grid Array (BGA) as the vertical interconnection and bracing between High-Temperature Co-fired Ceramic (HTCC) substrates in order to achieve a high-integration 3-D structure. Exploiting the HTCC multilayer layout, this paper presents the design and development of an ultra-wideband, compact and light, high-output power, four-channel, dual-polarization Transmit/Receive (T/R) Module. In this module, microwave circuits and power control circuits are highly integrated into electrically isolated HTCC layers or substrates, resulting in low coupling and crosstalk between signals. Furthermore, multichip assembly technology, multifunctional MMICs, and other high-integration technologies were adopted for this module. Each channel could provide more than 2 W transmit output power, more than 15 dB receive gain, and less than 5 dB receive noise figure. Every module contains four channels. The power supply and phase/amplitude conditioning of each channel can be controlled individually and showed good consistency of the amplitude and phase of all channels. The connectors of manifold port and polarization ports are all SSMP, which can achieve further integration. This module has also an automatic negative power protection function. The module has stabilized performance and mass production prospects.

The Advanced Indian MST Radar (AIR): System Description and Sample Observations

AbstractAn upgraded version of the Indian MST radar, called Advanced Indian Mesosphere‐Stratosphere‐Troposphere (MST) radar (AIR), has recently been commissioned. The prime objective of constructing the AIR is to make it a more useful instrument for conducting new experiments, which enable us to broaden our knowledge on the dynamical and electrodynamical processes including coupling from the boundary layer to the ionosphere. The AIR works at 53 MHz, and the system has been rebuilt, keeping the original square antenna array consisting of 1,024 Yagi antennae. The AIR is a high‐power, fully active phased array system with dedicated 1‐kW solid‐state transmit‐receive units, providing a total peak power of 1,024 kW, and control systems that allow steering the beam with 360° azimuth and 24° zenith agility. Also, the antenna system has been configured with modularity and scalability, which facilitates selection of antenna subarray and aperture for carrying out multireceiver experiments. The antenna radiation pattern tests reveal that the beam width and first side lobe level are close to the designed values of 2.2° and −13.2 dB, respectively. Currently, the system is equipped with 18 receivers to carry out spaced receiver experiments. The transmitters have been designed to transmit very short and long pulses for studying boundary layer to ionosphere. This paper presents the system description of the AIR and sample observations made using the system in Doppler beam swinging mode demonstrating its capabilities for studying neutral atmosphere and ionosphere.

A Multiple Element Calibration Algorithm for Active Phased Array Antenna

In this paper, we investigate an octagonal phase settings algorithm for multiple k th elements in improving the calibration techniques for an active phased array antenna using the power measurement output of each element. An active phased array antenna calibration requires simultaneous measurement of each antenna element of an array to guarantee high target precision to meet a specific operation. Therefore, each element in the active phased array antenna requires an efficient and accurate amplitude and phase variation in order to calibrate the array antenna system power output with the excitations of the antenna elements using linear equations to adjust the corresponding amplitude and phase errors. Calibration and optimization in an active phased array system steer antenna beam to the desired direction and they are applicable in radar communications, automobiles, communication systems, and electronic warfare.

바이어스 타이밍 기법을 이용하여 송수신 격리도가 개선된 소형 송수신 모듈

The transmit/receive(T/R) module is a key component in the active phased array system. The brick-type T/R module has been widely used and the miniaturization has been an important factor to get the flexibility of the system configuration. For the miniaturization, multi-function chips(MFC) having a common leg configuration are suitable to reduce the number of required MMICs and a high isolation between transmit and receive paths is necessary for the high gain T/R modules. In this work, we propose a bias timing scheme for the compact T/R module and show the optimum timing based on measurements, in order to improve the feed-back path loop problem and the consequent isolation problem of the common leg configuration. We have implemented high power(7 W/channel) and high T/R gain(35 dB transmit and 30 dB receive gains) within the half size() of the conventional T/R modules.

Modelling and design of a finite dual-polarised notch phased-array antenna

The authors present the modelling and design procedure for a finite dual-polarised notch phased-array antenna which has a triangular lattice to obtain a widescan ability in the azimuth and elevation planes. The array antenna has orthogonal linear polarisations for transmitting and receiving, and the triangular element grid is achieved by 45° rotation of a square grid of notch elements in egg-crate configuration. A numerical waveguide simulator for the H-plane scan is modelled to eliminate scan blindness in the H-plane. A numerical model for the finite dual-polarised notch array is built to investigate the convergence of the active-element pattern (AEP) and the effects of the grating lobe according to array size. To verify the numerical results, a wideband active phased-array system was fabricated which consists of a 10×12×2 notch array, 8×8 transmit/receive modules and beam-forming networks. The scan patterns measured by near-field measurement show good agreement with the converged AEP for the finite array model and have widescan performance in the azimuth and elevation planes.

Noise Signal Decorrelation in Broad-Band Active Phased Array Systems

Noise Signal Decorrelation in Broad-Band Active Phased Array Systems

Use of direct-modulated/gain-switched optical links in monopulse-type active phased array systems

With the advance of high speed laser technology, optical interaction with microwave circuits has become highly viable. Such interaction is advantageous as the fiber is low-loss, lightweight, and immune to electromagnetic interference. In this paper, interaction of direct-modulated and gain-switched optical links with active antenna phased array systems is demonstrated. In the direct-modulated optical system, the RF signal directly modulates the DFB laser. In the gain-switched optical system, the laser is gain-switched to function as a RF frequency doubler. The modulated signal is transmitted via an optical fiber and recovered at the receiving end by a high-speed photodetector. The recovered RF is then injected into the active antenna phased array systems as an injection-locking reference signal. Two active antenna systems are used for this demonstration: beam-switching and Doppler transceiver.

MU radar: New capabilities and system calibrations

The middle and upper atmosphere (MU) radar of Japan is a unique mesosphere‐stratosphere‐troposphere type radar with an active phased array system. The MU radar has proved so reliable that continuous trouble‐free operations over many days are possible. A brief description of new capabilities recently implemented and calibrations made to confirm the performance of the system are presented herein.

The MU radar with an active phased array system: 1. Antenna and power amplifiers

The MU (middle and upper atmosphere) radar of Japan is a 46.5‐MHz pulse‐modulated monostatic Doppler radar with an active phased array system. The nominal beam width is 3.6° and the peak radiation power is 1 MW with maximum average power of 50 kW. The system is composed of 475 crossed three‐subelement yagi antennas and an equivalent number of solid state power amplifiers (transmitter‐receiver modules). Each yagi antenna is driven by a transmitter‐receiver module with peak output power of 2.4 kW. This system configuration enables very fast and almost continuous beam steering that has not been realized by other mesosphere‐stratosphere‐troposphere radars. Also, a variety of sophisticated operations are made feasible by dividing the antenna array into several independent subarrays. A brief description of the system, particularly its antenna and power amplifiers, is presented herein.

The MU radar with an active phased array system: 2. In‐house equipment

The MU (middle and upper atmosphere) radar of Japan uses an active phased array system. Each of 475 crossed three‐subelement yagi antennas in a circular array is provided with a 2.4‐kW peak power amplifier. This system configuration attains a very fast and almost continuous beam steerability at the total peak radiation power of 1 MW. A brief description of the in‐house equipment is presented herein.

Monitoring of the MU radar antenna pattern by satellite OHZORA (EXOS-C)

As the first attempt among MST (mesosphere stratosphere troposphere) type radars, the MU (middle and upper atmosphere) radar features an active phased array system. Unlike the conventional large VHF radars, in which output power of a large vacuum tube is distributed to individual antenna elements, each of 475 solid state power amplifier feeds each antenna element. This system configuration enables very fast beam steering as well as various flexible operations by dividing the antenna into independent subarrays, because phase shift and signal division/combination are performed at a low signal level using electronic devices under control of a computer network. The antenna beam can be switched within 10 microsec to any direction within the zenith angle of 30 deg. Since a precise phase alignment of each element is crucial to realize the excellent performance of this system, careful calibration of the output phase of each power amplifier and antenna element was carried out. Among various aircraft which may be used for this purpose artificial satellites have an advantage of being able to make a long term monitoring with the same system. An antenna pattern monitoring system for the MU radar was developed using the scientific satellite OHZORA (EXOS-C). A receiver named MUM (MU radar antenna Monitor) on board the satellite measures a CW signal of 100 to 400 watts transmitted from the MU radar. The principle of the measurement and results are discussed.