Ku-band Frequency Research Articles

A Waveguide Switch Based on Contactless Gap Waveguide Technology

A novel dual-pole dual-throw (DPDT) waveguide switch is proposed for high-power and low-loss applications. The proposed DPDT was designed based on the contactless properties of the gap waveguide technologies in the Ku frequency band. The DPDT was composed of two concentric contactless cylinders. Standard rectangular waveguide ports (WR 75) and waveguide paths are machined in the middle of these cylinders. The rotational movement of the inner cylinder is realized using two bearings in the top and bottom of the DPDT. The proposed structure is fabricated and the measured results are in good agreement with the simulated ones. The measured insertion loss and return loss for the aligned ports are better than 0.1 and 25 dB in the frequency band ranging from 11 to 13.5 GHz, respectively, and the measured isolation between two adjacent ports is better than 60 dB.

Comparison of the GPM DPR Single- and Double-Frequency Products Over the Mediterranean Area

The NASA/JAXA Global Precipitation Measurement (GPM) Core Observatory (CO) carries, for the first time, a dual-frequency precipitation radar (DPR) designed to provide insights into the 3-D structure of precipitating clouds and rain intensity by using its Ka- and Ku-band frequencies. Single-frequency (SF) (both Ku- and Ka-only) and double-frequency (DF) based products provide particle-size distribution (PSD) parameters, as well as precipitation rates. Background surface type, precipitation type and phase, and vertical extension of the storm are also provided. In this paper, an intercomparison between the SF and DF DPR outputs over the Mediterranean area during rainfall events in the first four years of GPM-CO mission is carried out. The goal is to investigate the reliability of SF-based products by assessing their quality compared to the DF-based ones, treated as a reference. The vertical profiles and the near-surface values of the corrected reflectivity of the PSD parameters (mean mass-weighted diameter and normalized intercept) and of the rainfall rate have been analyzed. The data have been categorized for surface type (land and sea) and precipitation type (stratiform and convective). The results show a more marked difference between the DF and SF Ka-only based products than between DF and SF Ku-only based products. The feature is confirmed by the analysis of vertical profiles of the SF- and DF-based retrieved parameters. The statistical scores do not differ significantly between land and sea while they differ noticeably between stratiform and convective precipitation.

Study of Nusantara Satu Satellite parameter evaluation for broadband application in Indonesia

This study aims to evaluate the performance of Satellite Nusantara Satu which has just been launched. Nusantara Satu Satellite is a broadband satellite that uses High Throughput Satellite (HTS) technology and uses Ku-band transponders to cover all regions in Indonesia. However, the use of Ku-band frequencies in Indonesia, which is located at a tropical region, must be evaluated because of the characteristics of the Ku-band frequency are very vulnerable to rain attenuation. In general, a broadband service requires link availability of 99.9% with a minimum speed of 100 Mbps. Our simulation results show that in the western part of Indonesia, to reach 100 Mbps with 99.9% link availability, the EIRP of the earth station VSAT is minimum at 79 dBW. In the central part of Indonesia, to reach speeds of 100 Mbps with 99.9% link availability, the EIRP of the earth station VSAT is minimum at 83 dBW. And in the eastern part of Indonesia, to reach speeds of 100 Mbps with 99.9% link availability, the EIRP of the earth station VSAT is minimum at 84 dBW.

Analyses of Combined DSRR and EBG Structures Over SIW and HMSIW for Obtaining Band Pass Response

Effect of combination of dual split ring resonator and electromagnetic bandgap structures over substrate integrated waveguide and half-mode substrate integrated waveguide (HMSIW) transmission line sections to obtain band pass property is presented in this paper. Greater control over the insertion loss (IL) within the transmission pass-band as well as the stop band isolation of the BPF is obtained by detailed study on several parameters of the proposed structure. The proposed design is further miniaturized using HMSIW technique keeping other useful parameters unaltered. The BPF structure is designed considering Neltec NH9320 material of thickness 30 mils and dielectric constant of 3.2. The filter achieves very small IL and wider bandwidth covering major part of microwave Ku frequency bands (12–18 GHz) with good stopband isolation. The designs are fabricated and measured results come with close approximation with the simulated outcomes.

An improved method of designing optimum microstrip Rotman lens based on 2D‐FDTD

In this article we propose an efficient method for analysis of microstrip Rotman lens using two-dimensional finite difference time domain (2D-FDTD). Both the dielectric and conductor losses are modeled in this method in order to achieve results which are in good agreement with 3D simulation. Using 2D analysis, the required simulation time is reduced considerably, which in turn, enables us to use the proposed analysis method in an optimization procedure. Based on this optimization procedure, we present an improved design of a microstrip Rotman lens in which both the efficiency and also the gain of isotropic antenna array are increased. In this design, the Rotman lens has 5 beam ports and 16 array ports and operates in Ku frequency band.

Hardened Glass Particle and Carbon Black Using Resin for Potential Electromagnetic Shielding in Biomedical Electronic Equipments

This study aims to investigate the electromagnetic properties of a composite of hardened glass particle and carbon using resin in determining the absorbability of the composite for electromagnetic interference (EMI). The electromagnetic absorption measurement was conducted using T-R method (transmission-reflection) by measuring the dielectric constant, loss factor, real and imaginary part of permeability, reflection coefficient and transmission coefficient. The measurement is taken for X band frequency and Ku band frequency within the frequency range from 8.2GHz to 12.4GHz and 12.4GHz to 18GHz, respectively. Dielectric constant of sample decrease when frequency increases. The high dielectric constant of material implies that the material has high absorbability of field energy, resulting in high attenuation of the applied field.

Development of Self-Healable Organic/Inorganic Hybrid Materials Containing a Biobased Copolymer via Diels-Alder Chemistry and Their Application in Electromagnetic Interference Shielding.

In this study, a novel biobased poly(ethylene brassylate)-poly(furfuryl glycidyl ether) copolymer (PEBF) copolymer was synthesized and applied as a structure-directing template to incorporate graphene and 1,1′-(methylenedi-4,1-phenylene)bismaleimide (BMI) to fabricate a series of self-healing organic/inorganic hybrid materials. This ternary material system provided different types of diene/dienophile pairs from the furan/maleimide, graphene/furan, and graphene/maleimide combinations to build a crosslinked network via multiple Diels–Alder (DA) reactions and synergistically co-assembled graphene sheets into the polymeric matrix with a uniform dispersibility. The PEBF/graphene/BMI hybrid system possessed an efficient self-repairability for healing structural defects and an electromagnetic interference shielding ability in the Ku-band frequency range. We believe that the development of the biobased self-healing hybrid system provides a promising direction for the creation of a new class of materials with the advantages of environmental friendliness as well as durability, and shows potential for use in advanced electromagnetic applications.

Performance Enhancement of Reconfigurable Micro Strip Patch Antennae Using Metamaterials

Micro strip reception apparatuses are broadly utilized in wireless applications as a result of its simple design, compactness and economical. These small scale strip fix receiving antennas are made utilizing materials like FR4, Rogers RT duroid. These common materials are being supplanted with a helpful material named as Meta materials. These materials are unnatural materials having non-indigenous properties which are controlled with basic properties for the acquirement of updated properties. This whole procedure work with heterogeneous kinds of reconfigurable small scale strip fix receiving antenna utilizing Meta materials. Thus the exhibitions of smaller scale strip reception apparatuses are superior to whatever other conventional radio wires which likewise fill in as an inconceivable use for receiving antenna geeks and architects. The dynamic tuning of such receiving antenna parameters is commonly accomplished by changing the switch conditions. A solitary model can be utilized to help various capacities at different recurrence groups. Objective is to plan a reconfigurable micro strip patch antenna which works at four unique frequencies in X-band and Ku band. The reproduced reception apparatus emanates at five unique frequencies of 5.48 GHz, 9.88 GHz, 11.32 GHz, 12.68 GHz and 15.08 GHz and has an arrival loss of - 24.6103 dB, - 15.095dB, - 24.6103 dB, -30.0870 and - 30.8473 dB individually. And afterward it is manufactured utilizing FR4 as substrate and afterward it is observed to be in great match with the reproduced comes about.

Design of a substrate integrated waveguide matrix amplifier

Developments in microwave systems have increased the need for matrix amplifiers, which provide both high gain and wide frequency bands. The aim of this paper is to design a novel 2x4 matrix amplifier with a substrate integrated waveguide (SIW)-based power divider and combiner and a microstrip gain equalizer in the X and low Ku frequency bands. The proposed amplifier can be easily integrated with any microstrip, rectangular waveguide, or SIW-based circuits. The analysis and design of the amplifier is performed using two full wave simulators with different computational techniques (finite element method and finite integration technique) to verify the results. Simulation results show that the amplifier provides 16 dB gain with less than 4 dB ripple and more than 10 dB of input and output return losses in the frequency band of 8--15 GHz. This amplifier can be used as a wide band and high gain block in many microwave applications.

Investigation of the Broadband Microwave Absorption of Citric Acid Coated Fe3O4/PVDF Composite Using Finite Element Method

Magnetite (Fe3O4) have been thoroughly investigated as microwave absorbing material due to its excellent electromagnetic properties (permittivity and permeability) and favorable saturation magnetization. However, large density and impedance mismatch are some of the limiting factors that hinder its microwave absorption performance (MAP). Herein, Fe3O4 nanoparticles prepared by facile co-precipitation method have been coated with citric acid and embedded in a polyvinylidene fluoride (PVDF) matrix. The coated Fe3O4 nanoparticles were characterized by X-ray diffraction spectrometer (XRD), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), and vibrating sample magnetometer (VSM). COMSOL Multiphysics based on the finite element method was used to simulate the rectangular waveguide at X-band and Ku-band frequency range in three-dimensional geometry. The citric acid coated Fe3O4/PVDF composite with 40 wt.% filler loading displayed good microwave absorption ability over the studied frequency range (8.2–18 GHz). A minimum reflection loss of −47.3 dB occurs at 17.9 GHz with 2.5 mm absorber thickness. The composite of citric acid coated Fe3O4 and PVDF was thus verified as a potential absorptive material with improved MAP. These enhanced absorption coefficients can be ascribed to favorable impedance match and moderate attenuation.

Architecting 2D (LaBa2Fe3O8.55)0.3333 nanosheets using the modified sol-gel method and evaluation of their microwave, magnetic, and optical performance

The aim of this study was preparation of 2D (LaBa2Fe3O8.55)0.3333 nanosheets by the modified sol-gel route using the glucose as a novel precursor as well as evaluation of their microwave absorbing characteristics using the silicone rubber as an absorbing medium. The tailored nanoparticles were investigated using x-ray powder diffraction (XRD), field emission scanning electron microscopy (FE-SEM), fourier transform infrared (FT-IR), diffuse reflection spectroscopy (DRS), vibrating sample magnetometer (VSM), vector network analyzer (VNA). As demonstrated by the VNA results, the (LaBa2Fe3O8.55)0.3333/silicone rubber nanocomposite absorbed 50.71 dB at 13.7 GHz with a thickness of 1.5 mm while absorbed >2.66 GHz more than 20 dB and >6.36 GHz more than 10 dB along the x and ku-band with 2.0 mm in thickness. Interestingly, the effective bandwidth (>10 dB) of the (LaBa2Fe3O8.55)0.3333/silicone rubber nanocomposite was >4.71 GHz with 1.25–2.50 mm in thicknesses at the x and ku-band frequency. In this study, a novel, promising, thin, and broadband microwave absorbing nanostructure was designed.

Preparation and Investigation of Structural, Magnetic, and Microwave Absorption Properties of a SrAl1.3Fe10.7O19/Multiwalled Carbon Nanotube Nanocomposite in X and Ku-Band Frequencies

A magnetic composite of SrAl1.3Fe10.7O19 nanoparticles (NPs) and multiwalled carbon nanotubes (MWCNTs) was prepared using a modified Sol-gel method. The MWCNTs were functionalized using a mixture of sulfuric and nitric acids and then coated with SrAl1.3Fe10.7O19 NPs in the presence of poly(methyl methacrylate) (PMMA) in an argon atmosphere furnace. The crystalline structure was studied by X-ray diffraction (XRD) confirming the single phase and hexagonal structure (M-type ferrite) of the SrAl1.3Fe10.7O19 NPs. The magnetic properties of the as-prepared composites investigated by a vibrating sample magnetometer (VSM) revealed that the metallic magnetic NPs have greater magnetization compared to the SrAl1.3Fe10.7O19/MWCNT nanocomposite and exhibit acceptable magnetic behavior at room temperature. The maximum reflection loss of the sample having a coating thickness of 3.10 mm diameter and 30 weight percentage (wt%) of SrAl1.3Fe10.7O19/MWCNT was -44.08 dB at 9.56 GHz, possessing a bandwidth of 2.21 GHz with a microwave absorption up to 10 dB for the X-band. The comparison of the reflection loss in both the X and Ku-band frequencies of the individual components, i.e., silicone rubber, functionalized MWCNT, and SrAl1.3Fe10.7O19/silicone rubber, revealed that the synergistic effect of the components in the nanocomposite originate from a better impedance match. By reducing the thickness to 1.00 mm, the RL was reduced to -14.85 dB at 17.75 GHz possessing a bandwidth of 1.12 GHz (with a microwave absorption up to 10 dB) for the Ku-band. The microwave absorption of the sample was then studied in an anechoic chamber, and a similar result was obtained.

Wideband Ocean Altimetry Using Ku-Band and K-Band Satellite Signals of Opportunity: Proof of Concept

A proof-of-concept experiment has demonstrated that wideband (400 MHz) signals of opportunity (SoOp) transmitted in K- and Ku-bands from geostationary satellites can be used for coastal altimetry. An essential finding from this experiment is that the full broadcast spectrum consisting of multiple digital channels can be processed as a single wideband signal source. An established error model for Global Navigation Satellite System interferometric altimetry was shown to accurately represent the sea surface height (SSH) retrievals when evaluated using the full bandwidth. This experiment was conducted over a 72-h period at Platform Harvest off the Pacific Coast. Colocated tide gauge and LiDAR measurements were used as in situ data. Two anomalies were observed in the experiment: 1) multiple peaks in the cross correlation waveform from one polarization of Ku-band frequency and 2) decrease in signal-to-noise ratio from loss of a data channel. When the instances of multiple peaks were eliminated and the equivalent bandwidth recomputed using only the active channels, SSH error from these cases agreed well with the model prediction. Application of SoOp wideband altimetry will, therefore, require a monitoring capability to identify changes in the transmission spectrum, total power, and waveform shape, for quality control and setting an appropriate observation error covariance. Measurement precision from a satellite receiver is predicted to be between 4 and 6 cm using the error model. SoOp altimetry with these signals may improve coastal measurements and increase the sampling and revisit rate through the use of a constellation of small satellites.

Microwave permittivity of MWCNT, Ca1 − xBaxBi2Nb2O9 (0 ≤ x ≤ 1) and MWCNT/ Ca1 − xBaxBi2Nb2O9 (0 ≤ x ≤ 1) layered composite thick films using microstrip ring resonator overlay method

The microwave dielectric properties of the multiwalled carbon nanotubes (MWCNT) thick film, Ca1 − xBaxBi2Nb2O9 (x = 0, 0.2, 0.4, 0.6, 0.8, and 1) (CBBNO) thick films, and MWCNT/CBBNO layered thick film composites in the 8–18 GHz were determined by the overlay method using the microstrip ring resonator (MSRR). Microwave properties were studied by perturbation of MSRR due to the overlay of thick films of different materials. The MWCNT thick film, CBBNO thick film, and MWCNT/CBBNO layered composite thick films were screen-printed on an alumina substrate. The experimental data was obtained for the material and/or composition dependent peak output and the resonance frequency of the MSRR. In addition, the numerical results were obtained for first harmonic radiated in the X-band region from the MSRR operating in Ku-band (15.45 GHz) frequency region. The comparison was done for the X and Ku-band responses of MSRR due to perturbation of screen-printed MWCNT thick film, CBBNO thick film, and MWCNT/CBBNO layered thick film composites.

Design Procedure for Compact Dual-Circularly Polarized Slotted Substrate Integrated Waveguide Antenna Arrays

In this paper, a complete design procedure of low-profile dual-circularly polarized slotted substrate integrated waveguide antennas is developed at the Ku-band frequencies. The design method includes a recipe for controlling the beam squint angle, determining the optimum slot aperture distribution, and tapering slots coupling and excitation to increase the gain/efficiency and reduce the array sidelobe levels. The structure is designed in such a way to provide dual circular polarization and improve the radiation characteristics including reduced sidelobe levels using optimized symmetric nonuniform coupling factors and tapering the lengths of the slots. The radiation performance of the fabricated 64×12 slot antenna array has been tested using a planar near-field range measurement. The beam tilt angles in elevation, peak gain, cross polarization component, and sidelobe levels have been measured and compared to previously designed 32 × 13 and 16 × 12 slot arrays.

Preparation of flexible microwave interactive fabric for 8.2 to 18.0 GHz frequency: Functional evaluation and validation

In this study, for the first time, coating formulation based on milled carbon fibre has been applied on textile substrate to prepare flexible covering material for microwave protection. Cotton fabric with its inherent high dielectric property and finite length with close network of carbon milled fibre has synergised to generate highly conducting surface (σ = 96.22 S/m). The samples are prepared by coating of milled carbon fibre in various concentrations with polyurethane as binder on cotton fabric. Polyurethane contains hydroxyl and hexamethylene diisocynate groups which are polar under external electric field (dielectric constant 3.2–6.5) and also contribute high dielectric properties in coated fabric. Samples were evaluated for surface resistivity and microwave properties, i.e. permittivity, scattering parameters, reflection, transmission, absorption and reflection loss. Permittivity of high level (ɛ′: 21–31, ɛ″: 60–84) and attenuation of high order (α = 1971–2354 Np/m) are achieved. The sample coated with milled carbon fibre and polyurethane in ratio of 1: 1.67 on weight basis has shown 67–70% reflection, 28–30% absorption, 0.1–0.5% transmission, and EMI shielding of 28–30 dB in X (8.2–12.4 GHz) and Ku (12.4–8 GHz) frequency band. The results were further analysed theoretically and correlated with the scattering parameters and other microwave properties.

A Ku-band dual control path frequency synthesizer using varactorless Q-enhanced LC-type VCO

This study focused on the design principle and implementation of a high-frequency, wide-range frequency synthesizer by using a dual control path phase-lock loop (PLL) and a varactorless oscillator controlled by inductive–capacitive (LC-type) voltage (i.e., a voltage-controlled oscillator, VCO). Without a varactor in the LC tank, the tuned-transducer oscillator with Q-enhanced functionality can easily arrive at the requirements of high-frequency wide-range low-noise operations. We utilized a difference tuned varactorless VCO to create two different KVCOs and applied it to a dual control path PLL architecture to obtain wide tuning range and more favorable phase noise. In addition, a high-speed current-mode logic divider was employed given its high speed (because of the use of a transformer inductor), extremely high operation frequency, and wide-range. The proposed PLL was assembled using the standard 0.13-μm CMOS technology on a 0.95 × 1.05 mm2 chip. The PLL dissipated 40 mW at a 1.2 V supply. The measurement of phase noise at 17.64 GHz was − 98.12 dBc/Hz at a 1 MHz offset.

Simulation study for ground-based Ku-band microwave observations of ozone and hydroxyl in the polar middle atmosphere

Abstract. The Ku-band microwave frequencies (10.70–14.25 GHz) overlap emissions from ozone (O3) at 11.072 GHz and hydroxyl radical (OH) at 13.441 GHz. These important chemical species in the polar middle atmosphere respond strongly to high-latitude geomagnetic activity associated with space weather. Atmospheric model calculations predict that energetic electron precipitation (EEP) driven by magnetospheric substorms produces large changes in polar mesospheric O3 and OH. The EEP typically peaks at geomagnetic latitudes of ∼65∘ and evolves rapidly with time longitudinally and over the geomagnetic latitude range 60–80∘. Previous atmospheric modelling studies have shown that during substorms OH abundance can increase by more than an order of magnitude at 64–84 km and mesospheric O3 losses can exceed 50 %. In this work, an atmospheric simulation and retrieval study has been performed to determine the requirements for passive microwave radiometers capable of measuring diurnal variations in O3 and OH profiles from high-latitude Northern Hemisphere and Antarctic locations to verify model predictions. We show that, for a 11.072 GHz radiometer making 6 h spectral measurements with 10 kHz frequency resolution and root-mean-square baseline noise of 1 mK, O3 could be profiled over 8×10-4–0.22 hPa (∼98–58 km) with 10–17 km height resolution and ∼1 ppmv uncertainty. For the equivalent 13.441 GHz measurements with vertical sensor polarisation, OH could be profiled over 3×10-3–0.29 hPa (∼90–56 km) with 10–17 km height resolution and ∼3 ppbv uncertainty. The proposed observations would be highly applicable to studies of EEP, atmospheric dynamics, planetary-scale circulation, chemical transport, and the representation of these processes in polar and global climate models. Such observations would provide a relatively low-cost alternative to increasingly sparse satellite measurements of the polar middle atmosphere, extending long-term data records and also providing “ground truth” calibration data.

A Perspective on the Performance of the CFOSAT Rotating Fan-Beam Scatterometer

The China-France Oceanography Satellite (CFOSAT) to be launched in October 2018 will carry two innovative payloads, i.e., the surface wave investigation and monitoring instrument and the rotating fan-beam scatterometer [CFOSAT scatterometer (CFOSCAT)]. Both instruments, operated in Ku-band microwave frequency, are dedicated to the measurement of sea surface wave spectra and wind vectors, respectively. This paper provides an overview of the system definition and characteristics of the CFOSCAT instrument. A prelaunch analysis is carried out to estimate the scatterometer backscatter and wind quality based on the developed CFOSCAT simulator prototype. The overall simulation includes two parts: first, a forward model is developed to simulate the ocean backscatter signals, accounting for both instrument and geophysical noise. Second, a wind inversion processor is used to retrieve wind vectors from the outputs of the forward model. The benefits and challenges of the novel observing geometries are addressed in terms of the CFOSCAT wind retrieval. The simulations show that the backscatter accuracy and the retrieved wind quality of CFOSCAT are quite promising and meet the CFOSAT mission requirements.

Validation and Impact of SCATSAT-1 Scatterometer Winds

Scatterometer winds are useful in weather forecasting and cyclone monitoring related activities. The Indian Space Research Organization has launched SCATSAT-1, which is a follow-up mission of the Oceansat-2 scatterometer in September 2016. It operates in the Ku-band frequency and provides wind vector data over oceanic region from sun synchronous polar orbit. SCATSAT-1 wind vector data are validated against buoy observations, other scatterometer observations and numerical weather prediction (NWP) analysis. It is found that SCATSAT observations are of good quality in comparison with other similar types of measurements. Impact of assimilation of these observations in NWP forecasts is investigated using the National Centre for Medium Range Weather Forecasting Global Forecast System (NGFS). The NGFS model employs a three-dimensional variational-ensemble Kalman filter (3D Var-EnKF) hybrid assimilation system with a deterministic model of T-1534 resolution and 80 member ensembles of T-574 resolution. Impact of assimilation of SCATSAT-1 observations in prediction of the Kyant, Nada and Varadha cyclones formed in the Bay of Bengal region and impact on operational forecasts are discussed. Assimilation of SCATSAT observations produced marginal improvement in general NWP forecast statistics and improvement is observed in cyclone track forecasts if observations are available near the cyclone position at analysis time.