Phased Array Antenna Applications Research Articles

A high‐precision and fast off‐line beamforming pattern estimation technique for active phased array antenna application

A detailed modeling method including all states of each active devices is proposed in this work, aiming to achieve high-precision and fast off-line estimation of beamforming pattern. Experimental verification of hundreds of radiating patterns shows that the beam steering angle accuracy is able to obtain 0.2% (Tx mode) and 0.19% (Rx mode) beam width in average, respectively; and the beam width accuracy is 0.2% (Tx mode) and 0.39% (Rx mode) in average, respectively. Also, SLL accuracy can reach 0.01 dB (Tx mode) and 0.1 dB (Rx mode), respectively. By adopting this technology, the optimal beam controlling codes of large active phased array antenna (APAA) could be quickly derived. Furthermore, measurement and online compensation works of enormous quantities of beams could be greatly simplified.

Phase‐shifted circularly polarised ring microstrip antenna and application in phased array antennas

A phase-shifted circularly polarised ring microstrip antenna (PS-CP-RMSA), which can switch between three different phases, is proposed. The phase of a circularly polarised antenna can be shifted by changing the angle of rotation. Taking advantage of this property, the proposed PS-CP-RMSA comprises a circularly polarised ring microstrip antenna (CP-RMSA) with three groups of feed lines and perturbation elements; phase shift can be achieved by switching their groups. Thus, the phase of a circularly polarised antenna can be electronically shifted without phase shifters, which has been difficult in the past. Therefore, the PS-CP-RMSA array can perform beam tilt electronically. In this study, PS-CP-RMSA and its four-element array were designed, fabricated, and measured. The maximum circular polarisation gain of the prototype PS-CP-RMSA was 6.3 dBic with an axial ratio of 1.1 dB at 5.7 GHz. The maximum gain of the boresight directional beam of the four-element array was 11.3 dBic with an axial ratio of 0.4 dB at 5.67 GHz. The proposed antenna can be a candidate for a new beam-control method for array antennas.

Design of a pattern reconfigurable antenna for wide‐angle scanning phased array applications

AbstractIn this article, a pattern reconfigurable antenna is proposed for wide beam scanning phased array applications. Different from the wide beamwidth unit design, the large beam scanning range of the proposed antenna array is realized by the reconfigurable radiation patterns with the different tilted angles of the antenna unit. The tilted beams can enhance the total beam coverage range of the antenna unit with high directivity, thus increasing the beam scanning range of the antenna array. The tilted beams are realized by the combination of the concentric circular and annular patch antennas. A PIN diode‐loaded reconfigurable feeding network is designed to feed the patches with reconfigurable phase differences. The feeding network can achieve a good impedance matching effect and guarantee the symmetry of the tilted beams. To verify the beam scanning performance of the proposed antenna, a 1 × 4 linear array is fabricated and measured. The results prove that the antenna can achieve ±61° beam scanning range with ±78° 3 dB beam coverage range and the maximum sidelobe level (SLL) of −8.0 dB. The characteristics include low‐profile, high efficiency, low SLL, and wide beam scanning range making it a very attractive choice for phased array antenna applications.

3D printed lattice structure for lightweight Ka‐band phased array antenna

Here a lightweight antenna array is designed and fabricated for a Ka-band phased array antenna. From the perspective of advanced space-borne engineering practice, a Kagome lattice structure is proposed for the lightweight antenna array applications and the representative configurations of the proposed lattice structure is fabricated via selective laser melting (SLM). Experiment is performed to estimate the electrical performance with the featured structure. Compared with the conventional antenna array, the proposed one has 69% less weight, identical measured radiation patterns, and good electrical performance. The results demonstrate the great potentials for other readily customized lightweight phased array antenna applications.

Design and implementation of an adaptive beamformer for phased array antenna applications

AbstractA modular beamformer, fully scalable in amplitude and phase, to be used with transmitting antenna arrays operating in the Digital Cellular System (DCS)/Personal Communications Service (PCS) frequency band, is designed and fabricated in this paper. The implementation of the structure is simple and very low cost; its performance is evaluated by measuring the frequency response, as well as the radiation patterns produced by an antenna array connected to the output of the beamformer. The latter exhibits low return losses and average amplitude imbalance less than ±0.8 dB, whereas the phase deviations do not exceed ±6° on average, over its 300 MHz bandwidth.

Advanced RF and microwave functions based on an integrated optical frequency comb source.

We demonstrate advanced transversal radio frequency (RF) and microwave functions based on a Kerr optical comb source generated by an integrated micro-ring resonator. We achieve extremely high performance for an optical true time delay aimed at tunable phased array antenna applications, as well as reconfigurable microwave photonic filters. Our results agree well with theory. We show that our true time delay would yield a phased array antenna with features that include high angular resolution and a wide range of beam steering angles, while the microwave photonic filters feature high Q factors, wideband tunability, and highly reconfigurable filtering shapes. These results show that our approach is a competitive solution to implementing reconfigurable, high performance and potentially low cost RF and microwave signal processing functions for applications including radar and communication systems.

Application of Active Phased Array Antenna for Millimeter-wave Transfer to Beamed Energy Launch Vehicles

Application of Active Phased Array Antenna for Millimeter-wave Transfer to Beamed Energy Launch Vehicles

Beamforming system based on paralleled variable chirped microwave signal generators

Optically controlled beamforming technology has attracted a lot of research interest for its unique advantages and application in phased array antennas (PAAs). In this paper, a novel scheme of an optically controlled beamforming system based on an array of chirped microwave signal generators is proposed. In the proposed system, an array of photonic microwave delay line filters (PMDLFs) with quadratic phase response is configured, and chirped microwave signals, which are then applied to the antennas, are generated by processing a chirped-free Gaussian pulse by those filters, and the relative delay among those chirped microwave signals can be controlled by tuning the optical carriers’ wavelength in each path. Therefore, the system can realize optically controlled beamforming by successfully combining photonic generation of a chirped microwave signal with optical true time delay (OTTD). As the PMDLFs’ frequency response can be flexibly varied, the generated microwave signal waveforms can be adjustable to suit the needs of different applications. A theoretical analysis of the proposed beamforming system is carried out and its feasibility is verified by numerical simulations.

A true-time-delay networks design technique

This paper proposes a technique to design wide band switched-line (SL) true-time-delay (TTD) networks, commonly used for phased array antenna (PAA) applications. This study investigates the constant-delay behavior of switched-line phase shifters based on single-pole double-throw (SPDT) switches. Circuit sizing starts by considering the effective S-parameters of the switches, to use their non-idealities as an integral part of the phase shift linearly dependent to the frequency and by considering, from the beginning, the possible spatial positioning of elements that allows the circuit feasibility as a design target. The aim of this study is to provide a technique suitable for the design of well-matched TTD networks with a flat delay in wide bandwidth. In this paper, we propose new design formulas for which we show a single-frequency implementation. A computational strategy is used to obtain numerical solutions of the derived equations with this study. Finally, a monolithic X-band TTD circuit example is shown.

Waveguide‐integrated MEMS‐based phase shifter for phased array antenna

This study investigates a new concept of waveguide-based W-band phase shifters for applications in phased array antennas. The phase shifters are based on a tuneable bilateral finline bandpass filter with 22 microelectromechanical system (MEMS) switching elements, integrated into a custom-made WR-12 waveguide with a replaceable section, whose performance is also investigated in this study. The individual phase states are selected by changing the configuration of the switches bridging the finline slot in specific positions; this leads to four discrete phase states with an insertion loss predicted by simulations better than 1 dB, and a phase shift span of about 270°. MEMS chips have been fabricated in fixed positions, on a pair of bonded 300 µm high-resistivity silicon substrates, to prove the principle, that is, they are not fully functional, but contain all actuation and biasing-line elements. The measured phase states are 0, 56, 189 and 256°, resulting in an effective bit resolution of 1.78 bits of this nominal 2 bit phase shifter at 77 GHz. The measured insertion loss was significantly higher than the simulated value, which is assumed to be attributed to narrow-band design of the devices as the influences of fabrication and assembly tolerances are shown to be negligible from the measurement results.

Integrated Ultra-Low-Loss 4-Bit Tunable Delay for Broadband Phased Array Antenna Applications

We demonstrate the design, fabrication, and characterization of a 4-bit tunable delay in an ultra-low-loss ${\rm Si}_{3}{\rm N}_{4}$ planar platform. Temporal delays up to 12.35 ns with resolution of 0.85 ns are measured, for a total of 2.407 meters of propagation length. The TE waveguide propagation loss is measured to be $(1.01\pm 0.06)~{\rm dB}/{\rm m}$ at a wavelength of 1550 nm with the lowest loss of $(0.57\pm 0.08)~{\rm dB}/{\rm m}$ at 1591 nm.

Extremely High Tunability and Low Loss in Nanoscaffold Ferroelectric Films

There are numerous radio frequency and microwave device applications which require materials with high electrical tunability and low dielectric loss. For phased array antenna applications there is also a need for materials which can operate above room temperature and which have a low temperature coefficient of capacitance. We have created a nanoscaffold composite ferroelectric material containing Ba(0.6)Sr(0.4)TiO(3) and Sm(2)O(3) which has a very high tunability which scales inversely with loss. This behavior is opposite to what has been demonstrated in any previous report. Furthermore, the materials operate from room temperature to above 150 °C, while maintaining high tunability and low temperature coefficient of tunability. This new paradigm in dielectric property control comes about because of a vertical strain control mechanism which leads to high tetragonality (c/a ratio of 1.0126) in the BSTO. Tunability values of 75% (200 kV/cm field) were achieved at room temperature in micrometer thick films, the value remaining to >50% at 160 °C. Low dielectric loss values of <0.01 were also achieved, significantly lower than reference pure films.

High Integrated Microwave Architecture Using LTCC-SIP Technology in Active Phased Array Antenna Applications

AbstractA kind of three dimensional Low Temperature Co-fired Ceramic (LTCC)-System in Package (SIP) transition was proposed in this paper. The basic design of SIP with LTCC technology was done by vertical transitions which transmit the microwave signal from the bottom to the surface of the substrate. The measured insertion loss did not exceed 1.5 dB, which contains the insertion loss of the test board about 0.6 dB at 18 GHz and the return loss was better than

Compact photonic delay line constructed by holographic optical elements

To fully support phased-array antenna and other applications, a 3-range (long time, moderate time, and short time) delay line structures with holographic optical elements is proposed. Flexibility, light-weight, on-axis coupling, easy alignment, easy fabrication, and compactness are their advantages. When use holographic optical elements to build the photonic delay line system, all of the delay and non-delay paths in these three photonic delay lines are setting in a compact structure. They do not need any extra components, such as mirrors and optical paths in free space, and can bear stronger vibration. Therefore, the holographic optical elements are more suitable to design the photonic delay lines. In these three structures, their losses and crosstalk s are balanced. All of delay and non-delay cases in these three delay line structures, their crosstalk, signal-to-noise ratio, and loss are 1/81,000, 59.1 dB, and 3.2 dB, respectively. Finally, to support complete applications, a polarization independent photonic delay line system with holographic optical elements is proposed, too.

Fiber Bragg grating-based band edge delay line for radio frequency (RF) photonics applications

A fiber Bragg grating (FBG)-based delay line (or phase shifter) has been developed for microwave over fiber and phased array antenna (PAA) applications. The scheme uses band edge time delay of tunable fiber gratings to provide a continuously controllable microwave time delay or phase shift. Following the formulation and analysis of the device behavior, simulations of amplitude and phase responses are conducted. The results confirm the validity of theoretical predictions.

Novel Dual Circularly Polarized Radiating Element for Spherical Phased-Array Application

In this letter, the design of a novel dual circularly polarized (CP) radiating element suited for frequency reuse system is presented. Along with very good circular symmetric radiation pattern, this element has axial ratio better than 0.7 dB over 6% bandwidth and isolation between the LCP and RCP ports, better than 20 dB over 13% band width at X-band. With end-launch configuration, this element is very compact and well suited for spherical phased-array antenna (SPAA) application.

Study of dielectric characteristics of graded Ba1−xCaxZr0.05Ti0.95O3 thin films grown by a sol-gel process

The compositionally graded Ba1−xCaxZr0.05Ti0.95O3 (x = 0, 0.05, 0.10) (BCZT) thin films with compositional gradient from BaZr0.05Ti0.95O3 to Ba0.90Ca0.10Zr0.05Ti0.95O3 were deposited on Pt/Ti/SiO2/Si substrates by sol-gel processing. The crystal structure of the thin films was determined by X-ray diffraction. Field emission scanning electron microscopy (FESEM) was used to examine crystallite size and morphology of compositionally graded thin films. The dielectric properties of compositionally graded thin films were characterized by measuring the dielectric constant and dielectric loss as a function of temperature, applied electric field and frequency. As a result, compositionally graded thin films with weak temperature dependence were realized. Dielectric constant peaks, common to a ferroelectric transition, were not observed in the temperature range from 298 to 413 K. The compositionally graded BCZT thin films with weak temperature dependence of tunability could be attractive materials for frequency and phase agile tunable microwave components such as tunable filters, tunable oscillators, and phase shifters for application in phased array antennas.

Curve Fitting of Dielectric Constant and Loss Factor of ZrO2-Doped Barium Strontium Titanate for Application in Phased Array Antennas

DC electric field effects on the real part of the relative dielectric constant and the loss factor of barium strontium titanate for application in phased array antennas have been studied. The real part of the relative dielectric constant of the specimens decreases with increasing applied DC field. The loss factor under bias DC electric field is slighter than the real part of the relative dielectric constant under bias DC electric field does. The tunability is about 50% for barium strontium titanate doped with 0.5 wt % ZrO2 content. Variation of field coefficient A and tunability with ZrO2 contents have the same trend as that of the grain size. The real part of the relative dielectric constant of ZrO2-doped barium strontium titanate decreases rapidly before 1.0 kV/cm and slowly after 1 kV/cm compared within the data obtained by the curve fitting with Johnson's model. Compared with the fittings with the Johnson's model, the fittings with the Heywang model exhibit a small deviation between the testing and fitting data at a high applied voltage level. There is a conduction loss mechanism other than the intrinsic dielectric loss for the dielectric loss under bias electric field.

Effect of DC biasing field on dielectric properties of ZrO2-doped barium strontium titanate

Effect of DC biasing field on dielectric properties of (Ba0.6Sr0.4)TiO3 and ZrO2-doped (Ba0.6Sr0.4)TiO3 for application in phased array antennas have been characterized. The grain size is maximum for (Ba0.6Sr0.4)TiO3 doped with 0.5 wt% ZrO2 content. The real part of the relative dielectric constant of the specimens decrease with increasing applied DC biasing field. The tangent loss of the specimens is influenced much less by the DC biasing field than the real part of the relative dielectric constant. The tunability of the real part of the relative dielectric constant is about 45% for (Ba0.6Sr0.4)TiO3 doped with 0.5 wt% ZrO2 content.

Active integrated photonic true time delay device

A photonic true time delay cell with two waveguide couplers and five semiconductor optical amplifiers is demonstrated. The five semiconductor optical amplifiers provide gain in the 1550-nm region and port selection to determine the time delay. With the amplifiers off the signal are blocked with extinction ratios of more than 10 dB. In the experiments reported here, the delay of 20 ns was provided by an optical fiber. Because of the potential for nanosecond switching times, the device has application in very agile phased array antenna applications, in optical switching and routing, and in optical filtering.