X-band Antenna Research Articles

An X-Band 5 Bit Phase Shifter With Low Insertion Loss in 0.18 $\mu{\rm m}$ SOI Technology

This letter presents a 5 b phase shifter using a commercial 0.18 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\mu{\rm m}$</tex></formula> SOI process for X-band phased array antenna. The phase coverage of 360 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$^{\circ}$</tex></formula> with the LSB of 11.25 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$^{\circ}$</tex> </formula> is achieved at 8–12 GHz. The RMS phase error and amplitude variation are less than 6.5 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$^{\circ}$</tex> </formula> and 0.5 dB, respectively. The measured insertion loss is less than 10.8 dB, and the input and output return losses are over 12 dB at 8–12 GHz. The current consumption is nearly zero with 1.8 V supply. The chip size is <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$1.14\times 0.78\ {\rm mm}^{2}$</tex></formula> excluding pads. To the authors' knowledge, this is the first demonstration of X-band phase shifter using a commercial SOI technology.

X-band composite right/left-handed leaky wave antenna with large beam scanning-range/bandwidth ratio

A novel composite right/left-handed (CRLH) transmission line cell (TLC) based on a substrate integrated waveguide is proposed, which can be used for a leaky wave antenna for achieving large beam scanning-range/bandwidth ratio. Compared with previous CRLH TLCs, the proposed one has a narrower fast wave region where the propagation constant beta changes from -k(0) to +k(0). An X-band leaky wave antenna (LWA) has been designed and fabricated and measurements are presented. Both simulated and experimental results show that the developed LWA has a narrow fractional bandwidth of 26% (from 8.3 to 10.8 GHz) while having a continuous wide beam scanning range of -65 degrees to +54 degrees.

A Half Maxwell Fish-Eye Lens Antenna Based on Gradient-Index Metamaterials

An X-band half Maxwell fish-eye lens antenna is designed based on the effective medium theory and metamaterials technology. The non-resonant I-shaped metamaterials have been chosen to realize the lens antenna due to the broadband and low-loss features. The laboratory prototype has been fabricated and measured using a two-dimensional near-field microwave scanning apparatus, where the experimental results agree with full-wave numerical simulations.

Transmit–Receive Isolation Improvement of Antenna Arrays by Using EBG Structures

The mushroom-like electromagnetic band-gap (EBG) structure combined with a choke structure is applied to improve the transmit-receive (T/R) isolation of two X-band large antenna arrays. The basic idea presented is to suppress the surface wave propagation between the T/R arrays by utilizing EBG walls formed through a vertical configuration of the EBG cells, so as to improve the T/R isolation. The isolation level of the arrays with the EBG walls and a metal choke is measured and compared to other isolation methods applied. The experimental results show that by using this combined structure, the isolation level can be improved by at least 30 dB in the radar's operation band, which shows its high efficiency.

基于漏波波导的X波段高功率微波天线

基于漏波波导的X波段高功率微波天线

基于漏波波导X波段高功率微波天线的实验

基于漏波波导X波段高功率微波天线的实验

A Lightweight Organic X-Band Active Receiving Phased Array With Integrated SiGe Amplifiers and Phase Shifters

This paper presents for the first time an X-band antenna array with integrated silicon germanium low noise amplifiers (LNA) and 3-bit phase shifters (PS). LNAs and PSs were successfully integrated onto an 8 × 2 lightweight antenna utilizing a multilayer liquid crystal polymer (LCP) feed substrate laminated with a duroid antenna layer. A baseline passive 8×2 antenna is measured along with a SiGe integrated 8×2 receive antenna for comparison of results. The active antenna array weighs only 3.5 ounces and consumes 53 mW of dc power. Successful comparisons of the measured and simulated results verify a working phased array with a return loss better than 10 dB across the frequency band of 9.25 GHz-9.75 GHz. A comparison of radiation patterns for the 8×2 baseline antenna and the 8×2 SiGe integrated antenna show a 25 dB increase in gain (ΔG). The SiGe integrated antenna demonstrated a predictable beam steering capability of ±41°. Combined antenna and receiver performance yielded a merit G/T of -9.1 dB/K and noise figure of 5.6 dB.

Study of LDPE/TiO2 and PS/TiO2 Composites as Potential Substrates for Microstrip Patch Antennas

Low-density polyethylene (LDPE)/titania (TiO2) and polystyrene (PS)/titania (TiO2) composite systems have been developed as alternative substrates for microstrip patch antennas (MPA) for handheld devices. Morphological, thermal, and microwave characterizations of these composites have been conducted for different volume fractions of TiO2 in the polymer matrix. The size of the titania particles was found to be of the order of 0.5 μm, and their distribution in the composite was quite uniform. Composite materials showed an improvement in thermal and microwave properties over the parent polymer. Verification of these composites as potential substrates for MPA was carried out by fabricating simple rectangular patch X-band antennas. Materials with optimized substrate properties were chosen to design the MPA. The patches were designed with 4% volume fraction TiO2 in the LDPE composite system and 6% volume fraction TiO2 in the PS composite system. Return loss of ∼18 dB was observed for both systems.

Computer-Automated Evolution of an X-Band Antenna for NASA's Space Technology 5 Mission

Whereas the current practice of designing antennas by hand is severely limited because it is both time and labor intensive and requires a significant amount of domain knowledge, evolutionary algorithms can be used to search the design space and automatically find novel antenna designs that are more effective than would otherwise be developed. Here we present our work in using evolutionary algorithms to automatically design an X-band antenna for NASA's Space Technology 5 (ST5) spacecraft. Two evolutionary algorithms were used: the first uses a vector of real-valued parameters and the second uses a tree-structured generative representation for constructing the antenna. The highest-performance antennas from both algorithms were fabricated and tested and both outperformed a hand-designed antenna produced by the antenna contractor for the mission. Subsequent changes to the spacecraft orbit resulted in a change in requirements for the spacecraft antenna. By adjusting our fitness function we were able to rapidly evolve a new set of antennas for this mission in less than a month. One of these new antenna designs was built, tested, and approved for deployment on the three ST5 spacecraft, which were successfully launched into space on March 22, 2006. This evolved antenna design is the first computer-evolved antenna to be deployed for any application and is the first computer-evolved hardware in space.

Aperture Antenna Modeling by a Finite Number of Elemental Dipoles From Spherical Field Measurements

A method to determine a distribution of a finite number of elementary dipoles that reproduce the radiation behavior of the antenna under test (AUT) from truncated spherical field measurements is proposed. It is based on the substitution of the actual antenna by a finite number of equivalent infinitesimal dipoles (electric and magnetic), distributed over the antenna aperture. This equivalent set of elementary dipoles is optimized using the transmission coefficient involving the spherical wave expansion of the measured field and using an appropriate matching method. Once the current excitation of each dipole is known, the radiated field of the antenna at different distances can be rapidly determined. Moreover, using an iterative simplification procedure, the number of equivalent dipoles is reduced, which eases the implementation of the antenna equivalent model in any existing electromagnetic code. The feasibility, the reliability and the accuracy of the method are shown using experimental data issued from the measurement of an X-band horn antenna, in two different measurement setups.

TerraSAR-X Instrument Calibration Results and Extension for TanDEM-X

Spaceborne remote sensing with synthetic aperture radar (SAR) has become an essential source of high-resolution and continuous Earth observation. Modern satellites like the German TerraSAR-X system provide state-of-the-art radar images with respect to operating flexibility and imaging quality. The outstanding performance of TerraSAR-X image products is achieved by an innovative calibration approach that minimizes systematic antenna and instrument characteristics. The active phased array X-band antenna is fed by 384 transmit/receive modules for electronic beam steering and shaping in the azimuth and elevation direction. The flexible radar instrument hosts an internal calibration system which guarantees the high radiometric stability of all SAR products. New techniques for antenna performance control have been successfully implemented, setting a high standard for next-generation SAR missions. This paper summarizes all essential calibration results of TerraSAR-X that cover internal instrument behavior. Furthermore, we give an outlook on the required bistatic calibration techniques for the future TanDEM-X mission that faces additional performance challenges when calibrating two TerraSAR-X satellites flying in close formation.

E -plane sectoral horn power divider

E-plane sectoral horn power divider design method for high-power antenna array applications is presented. In this method, power division is proportional to the cross section areas of the waveguide channels at the aperture of an E-plane sectoral horn antenna. Two different power dividers are designed and produced to be used with an X-band antenna array having 30 dB Taylor distribution. The first one employs a simple E-plane sectoral horn antenna. This straightforward application of the method might be limited with production tolerances. The second one incorporates a corrugated E-plane sectoral horn antenna, whose design is relatively complex but less sensitive to production tolerances. The produced dividers are compared based on simulations and measurements and good agreement with the theoretical expectations is observed for both types.

절전센서용 X-밴드 대역 패치 어레이 안테나 설계

This paper introduces an X-band microstrip patch array antenna that can be suitable for an energy saving system. The presented patch antenna comprises with 2-element linear array. The antenna is simulated using CST MWS and manufactured using FR-4(h

An Efficient Method for Performance Monitoring of Active Phased Array Antennas

Modern synthetic aperture radars (SARs) are equipped with active phased array antennas to electronically generate various antenna beams. The TerraSAR-X satellite is a high resolution SAR system launched in June 2007. Its active phased array X-band antenna hosts 384 transmit/receive modules (TRMs) for controlling the electronic beam steering in azimuth and elevation direction. The precise modeling of the antenna performance is only possible if the actual characteristics of each individual TRM are monitored. TerraSAR-X has been equipped with an innovative characterization mode based on a coding technique, which is the so-called pseudonoise gating method. The individual and simultaneous characterization of all TRMs is realized under most realistic conditions with power supply loads like in nominal radar operation. For the first time, this novel technique has been applied on a spaceborne SAR system.

Radar Cross Section Measurements and Simulations of a Model Airplane in the X-band

The objective of this study was to illustrate how difierent methods of obtaining the Radar Cross Section (RCS) of an object may produce difierent results. RCS diagrams of a metallic airplane model (length, 0.64m) were obtained in an anechoic chamber, with a Lab- Volt RCS system, and simulated with a simulation software. The measurements and simulations were carried out at the radar frequency of 9.4GHz. The resulting RCS diagrams show that although there was a good correspondence between the main features in the RCS diagrams, some difierences can still be observed, highlighting the need for difierent techniques to fully represent the RCS of an object. Radar cross section (RCS) diagrams are usually di-cult to interpret due to the fact that they are two-dimensional representations of three-dimensional objects. Moreover, the di-culty in interpret- ing RCS diagrams is dependent upon the geometry of the object and, sometimes, on the techniques used to measure or calculate the RCS. Measurements are also afiected by many external factors, such as instrumental errors, spurious re∞ections and interferences, which can degrade the quality of the experimental data. In this study, we measured the RCS of an airplane model with a conduct- ing surface using two difierent experimental set-ups, and also simulated its RCS using commercial electromagnetic simulation software. The comparison of the data obtained shows that difierences will arise regardless of the care taken while performing an experiment or carrying out simulations and that these difierences should be taken into consideration when interpreting the data. 2. EXPERIMENTAL MEASUREMENTS The experimental data were collected using two difierent experimental setups: One inside an ane- choic chamber and another in a laboratory room using the Lab-Volt Radar Training System. The anechoic chamber, is located in the Instituto de Fomento Industrial (IFI/CTA, Brazil). Figure 1 shows the radar antennas used in the measurements. These X-band horn antennas were manufactured by M2SAT (Brazil); each antenna has a gain of 10dBi, and symmetric radiation patterns with low level of secondary lobes. The radar operated at 9.4GHz, in a quasi-monostatic conflguration and vertical polarization. A HP8360B (HP, USA) synthesized CW generator was use to generate the microwave radiation and the re∞ected signal was analyzed by a HP8593E (HP, USA) spectrum analyzer. It is estimated that the deviation of the RCS measurements was within 0.7dB. The model used in the measurements is also shown in Figure 1; it is a scale model of a Boeing 777 with total length of 0.64m (» 20‚). The body of the model is composed of an epoxy resin and its surface is coated with aluminum (the thickness of the coating is about 10 times larger than the skin depth of the aluminum at this frequency). The distance between the radar antennas and the model was about 6m. Electronic Warfare Laboratory (LGE/CTA, Brazil), consisting of interconnected subsystems that allow detailed studies of RCS in a laboratory environment. Measurements were carried out with inverse synthetic aperture radar, operating also at 9.4GHz at short range, in the presence of noise and clutter. The efiects of noise and clutter were removed using time-gating and subtraction techniques during the measurements. For the measurements, the distance between antenna and model was the same one used for the measurements in the anechoic chamber. Figure 2 shows the arrangement of the radar antenna and the model in the laboratory. The model was placed on a Styrofoam pedestal, invisible to radar waves.

Photonic dual RF beam reception of an X band phased array antenna using a photonic crystal fiber-based true-time-delay beamformer

We report dual RF beam reception of an X band phased array antenna using a photonic crystal fiber (PCF)-based delay network. Each incoming RF signal can be independently received, and the angle of arrival can be determined based on the delay time-dependent wavelength. Two RF signals with frequencies 8.4 and 12 GHz impinge upon an X-band antenna array from -7.4 degrees and -21.2 degrees . These signals are detected, and the angle of arrival is determined with a very good degree of accuracy using PCF-based true-time delay. The total number of RF beams that can be simultaneously detected is limited by the hardware availability and the bandwidth of the wavelength differentiation capability of the system.

Electro-optic probing of microwave fields using a wavelength-tunable modulation depth

A design for an electro-optic microwave-field-mapping system that eliminates the need for the polarizer, analyzer and quarter-wave retarder in its optical-probe-beam path, while also exhibiting less laser-induced noise and an enhanced signal-to-noise ratio as compared to conventional single- or double-pass electro-optic intensity modulators, is conceived and demonstrated. The measurement approach utilizes a high-reflection, resonant-microcavity probe, an entirely fiber-enclosed optical-beam path and a photonic heterodyne-mixing technique. A model for the reflective resonant probe is proposed and then employed to calculate electro-optic phase retardation and a modulation–efficiency slope, the latter of which is found to indicate that system sensitivity can be optimized via tuning of the input laser wavelength. This concept is experimentally verified using thin lithium tantalate electro-optic probe crystals configured as balanced resonators, and then an entirely fiber-coupled measurement is demonstrated in a variety of near-field, spatial scans over an X-band patch antenna.

Photonic Crystal Fiber-Based True-Time-Delay Beamformer for Multiple RF Beam Transmission and Reception of an X-Band Phased-Array Antenna

We report multiple beam transmission and reception of an X-band phased antenna array utilizing highly dispersive photonic crystal fiber (PCF), which has a dispersion value of - 600 ps/nm/km at 1550 nm, as true-time-delay (TTD) elements. In the transmission mode, two RF signals with frequencies 8.4 and 12 GHz are simultaneously steered at angles 7.4 and 21.2 degrees, respectively. In the receiving mode experiment, two RF signals with frequencies 8.4 and 12 GHz impinging upon an X-band antenna array from angles -7.4 and -21.2 degrees, respectively, are detected and the angles of arrival are determined accurately. Many RF beams can be simultaneously transmitted or received. The demonstration is only limited by the hardware availability and the bandwidth of the wavelength differentiation capability of the system.

X-band coaxial monopole antenna with an additional metal screen

The novel coaxial monopole antenna design with an additional metal screen is presented. The radiation char- acteristics of this antenna are investigated depending on a dis- tance between the ground plane and additional metal screens, as well as on a size of the latter. Measured and calculated ra- diation patterns are compared within limits of the operative frequency band and their revealed distinctions are discussed. The antennas characteristics allow pronounce that it can be considered as a promising candidate for various practical ap- plications both a single radiator and a composite element of antenna arrays.

Delay-time-enhanced photonic crystal fiber array for wireless communications using two-dimensional X-band phased-array antennas

Continuously tunable optical true time-delay (TTD) modules based on dispersion-enhanced photonic crystal fibers (DEPCFs) are demonstrated to provide continuous microwave squint-free beam scanning for an X-band (8 to 12 GHz) phased-array antenna (PAA) system. The dispersion of the fabricated photonic crystal fibers (PCFs) is as high as –600 ps/nm km at 1550 nm. By employing PCFs to increase the dispersion, the TTD module size can be proportionally reduced. The time delay is continuously tunable from –31 ps to 31 ps between adjacent delay lines by tuning the laser wavelength continuously from 1528 to 1560 nm. The far-field radiation patterns of a 1×4 subarray were measured from –45 to 45 deg scanning angles. Squint-free operation is experimentally confirmed. Wavelength conversion is also demonstrated to confirm that time-delay information can be successfully transferred from one wavelength to the other without being changed, which is suitable to be implemented in 2-D phased-array antenna systems. The TTD formation idea presented is suitable for not only the X band, but also the other higher microwave frequencies, such as the K band.