Ku-band Range Research Articles

Circularly polarized cup shaped patch antenna for Ku band application

A simple and compact antenna with dual band along with dual circular polarization is designed. The proposed antenna resembles a cup like shape which is actually a semicircle attached to the microstrip feed line in the patch part. From the dual notch frequency band, the first notch is from 12.2 – 13.5 GHz, second notch is from 14.8 – 16.4 GHz.Both the first and second notch bandwidth falls under the Ku band which ranges from 12 – 18 GHz. The proposed antenna also satisfies the circular polarization whose axial ratio bandwidth comes under the range of impedance bandwidth with a frequency range of 12.3 – 13.2 GHz and 15.3 – 16.3 GHz which satisfies the frequency range of Ku band (12-18 GHz). The simulation process is carried out by using the software Ansoft commercial high frequency structure simulator (HFSS ver. 21).

Effect of copper sulfide nanosphere shell on microstructure and microwave absorption properties of cobalt ferrite/carbon nanotube composites

Copper sulfide/cobalt ferrite/multi-walled carbon nanotube (CuS/CoFe2O4/MWCNT) microwave absorbing composites were prepared using a one-step hydrothermal method. The MWCNTs serve as skeletons with small CoFe2O4 spheres and CuS nanoparticles attached to the surface, developing a tube-sphere microstructure. We observed that CoFe2O4 connects MWCNTs and CuS by forming the C-O and S-O covalent bonds, respectively. CuS plays an important role in the adjustment of electromagnetic parameters, i.e., increasing the electromagnetic wave attenuation capacity and decreasing the characteristic impedance. The optimized composite exhibits good microwave absorption properties with a maximum microwave absorption bandwidth of 5.26 GHz at the matching thickness of 1.77 mm. In particular, the minimum reflection loss of the composite can reach − 58.74 dB at 17.52 GHz with the matching thickness of 4.64 mm, showing a great application prospect in the field of high-frequency electromagnetic wave absorption, e.g., in the Ku band range. The theoretical calculations demonstrate that the electronic structure of the material has changed in the presence of CuS. The energy barrier for electron transfer is reduced, promoting the formation of a specific charge transfer channel, which strengthens the microwave absorption properties of the composites.

Dual circularly polarized semi‐cylindrical hybrid dielectric resonator antenna for X and Ku ‐band applications

A hybrid dielectric resonator antenna (HDRA) with a single-probe generating circular polarization (CP) simultaneously at X and Ku-bands is presented in this article. A novel hybrid structure of semi-circular patch and semi-cylindrical dielectric resonator (DR) of equal radius are combined with a single-point probe feed to achieve dual-functional wide CP bands. The asymmetric nature of the semi-circle and semi-cylinder produces two orthogonal modes in their respective bands for CP radiation. The measured impedance bandwidth obtained by the proposed structure is 36.49% (3750 MHz) at X-band and 14.23% (2100 MHz) at the Ku-band range of frequencies. Axial ratio (AR) bandwidth of 30.39% (3100 MHz) is obtained at X-band and 13.24% (1950 MHz) at Ku-band. The measured gains are 9.54 dBic at 9.6 GHz and 6.55 dBic at 15 GHz. An excellent agreement between the computed and measured results validates the design of the dual functional circularly polarized HDRA.

A novel approach to prepare polyaniline/Polypyrrole@Cu-BTC/NH2-MIL-101(Fe) MOFs for electromagnetic wave absorption

In this study, the Cu-BTC and NH2-MIL 101 (Fe)@polypyrrole and polyaniline core–shell particles were prepared by in situ polymerization of pyrrole and aniline monomers on the surface of Cu-BTC and NH2-MIL 101 (Fe) for electromagnetic wave absorption applications. Firstly, the Cu-BTC (1,3,5 benzenetricarboxylic acid, BTC) and NH2-chromium (III) terephthalate (MIL-101) were synthesized by solvothermal method. Secondly, the surface of Cu-BTC and NH2-MIL 101 (Fe) mixtures were coated with polypyrrole (PPy) and polyaniline (PANI) by a polymerization of aniline (An) and pyrrole (Py) monomers and denoted as PP@Fe/Cu. For comparative studies, the aniline (An) and pyrrole (Py) monomers were polymerized in the same condition on the surface of NH2-MIL-101 (Fe) powder without the presence of Cu-BTC and the final powder was denoted as PP@Fe. The morphologies, phase structures and magnetic properties of products were characterized by scanning electron microscope (SEM), X-ray diffractometer (XRD), and vibrating sample magnetometer (VSM) machines. The complex permeability and permittivity values of PP@Fe and PP@Cu/Fe were determined in the range of Ku band (12.4–18 GHz). The electromagnetic wave absorption performances were evaluated using obtained permittivity and permeability values. It was observed that PP@Fe and PP@Cu/Fe composites displayed excellent microwave absorption performances. The existence of Cu-BTC into NH2-MIL 101 (Fe) further enhanced the minimum reflection loss from −60 dB to −80 dB.

An off‐center‐fed compact wideband antenna with truncated corners and parasitic patches for circular polarization

A novel single-fed circularly polarized wideband, compact and lightweight microstrip patch antenna (MPA) is proposed. The antenna is designed in a simple two-phase procedure to achieve wideband and circular polarization. In the first phase, an off-centered L-shaped feeding arrangement is employed to obtain wideband (|S11| < −10 dB) over 10.6 GHz to 14.7 GHz with an improved peak gain of 5.25 dBi. In the second phase, the radiating patch is symmetrically truncated and two modified-parasitic patches are added to ensure <3 dB axial ratio over 11.4 GHz to 12.8 GHz. A prototype has been fabricated and the measured results show close agreement with the simulation. The proposed antenna is suitable for fixed satellite and broadcast satellite communication in Ku-band range.

Design of Efficient Microwave Absorbers Based on Cobalt-Based MOF/SrFe10CoTiO19/Carbon Nanofibers Nanocomposite

In this study, nanocomposites with microwave absorption capability were synthesized based on cobalt-based MOF/SrFe10CoTiO19/carbon nanofibers. The microstructural, morphological, and magnetic characteristics were examined via X-ray diffraction, field emission scanning electron microscopy, and vibrating sample magnetometer, respectively. The microwave absorption properties of single-layer microwave absorbers were examined in the ku-band frequency range of 12.5–18 GHz. For the single-layer absorbers, the absorption characteristic of nanocomposite of all components is more efficient than that of sample containing just only cobalt-based MOF or doped strontium hexaferrite nanoparticles. The composite containing 70 wt.% cobalt-based MOF, 29 wt.% doped strontium hexaferrite, and 1 wt.% carbon nanofibers nanocomposite reached − 19 dB with 3.9 GHz bandwidth in the range of ku-band with the thicknesses of only 2.5 mm. The addition of carbon nanofibers (CNFs) has increased the interfacial polarization, while dipole polarization enhanced due to interactions between CNFs and Co/C. Capacitor-like structures will be formed due to the dielectric difference between components and so on generates great space-charge polarization. Enhanced in these parameters may be linked to increase in the magnetic and dielectric losses and increase the microwave absorption characteristic. Cobalt-based MOF/SrFe10CoTiO19/carbon nanofiber nanocomposite can be used as a potential candidate for microwave absorbers with strong absorption capability.

High dielectric ring resonators for designing passive filter

In this paper, the utilization of high dielectric constant resonator as a passive element for design of filter in the range of Ku band is investigated. The design is based on a new kind of dielectric resonator fabricated with a commercial high dielectric constant EPOXY paste. The design is based on a microstrip line periodically loaded with a new kind of dielectric resonator fabricated with a commercial high dielectric constant Epoxy paste compatible with serigraphy and screen printing technology.

Development of software for Ku-Band signal availability due to rain attenuation

&lt;span&gt;Ku-Band signal is often used for satellite communication mainly for direct to home (DTH) broadcasting. One of the major issues using this band is that the signal will be affected by raindrops. Raindrops absorb and scatter signal that operates at a frequency of more than 10 GHz. However, studies have been done to predict and measure the rainfall rate and rain attenuation. The rain attenuation in Ku-Band range and the rain rate were measured at satellite receiving dish, pointed towards the orbital slot 91.5 E over a one-year period in 2013. The cumulative distribution of rain rate obtained as well as a cumulative distribution of rain attenuation obtained are presented and compared with the rain prediction models. The aim is to get the best model to be used for the purpose of software development. It was found out that the DAH prediction model is fairly equitable when compared to direct satellite dish receiving measurements in Malaysia. The model provided a suitable baseline in developing a user interface software for weather prediction.&lt;/span&gt;

Structural, Magnetic and Microwave Absorption Properties of Ba0.5Sr0.5Ni2−x (MgZn) x/2Fe16O27 Hexaferrite Nanoparticles Prepared by the Sol-Gel Combustion Method

In this study, Sr–Ba hexaferrite nanoparticles ( ${\text {Ba}}_{\mathrm {0.5}}{\text {Sr}}_{\mathrm {0.5}}{\text {Ni}}_{\mathrm {2-}x}\left (\text {MgZn} \right )_{\frac {x}{\mathrm {2}}} {\text {Fe}}_{\mathrm {16}}\mathrm {O}_{\mathrm {27}}$ , x = –0.6, in the step of 0.2) was synthesized by the sol-gel method. The influence of Mg–Zn substitution on the structure and microwave absorption properties of Ni–W-type hexaferrite were investigated by technical methods such as x-ray diffraction, vector network analyzer, transmission electron micrograph and vibrating sample magnetometer. TEM images illustrated almost spherical particles with an average size of 35–52 nm. The M–H loops for all samples were measured at room temperature by vibrating sample magnetometer. Saturation magnetization (Ms) and coercivity (Hc) were derived from the hysteresis loops. The maximum field used in this measurement was 9 kilo-Oersted (kOe) Finally, the microwave absorption properties of these samples were investigated in Ku band range. The thickness of the composites was 2 mm in microwave absorption measurements. The results showed that the synthesized samples have a great potential in many fields of industry.

Study on Dielectric and Magnetic Properties of MWCNTs/Polyester Composites

This paper is to study the dielectric properties, magnetic properties, and dielectric conductivity of Multi-walled carbon nanotubes (MWCNTs) and polyester (PE) composites. The composites with different amount of MWCNTs (5-15%) have been studied in the Ku-Band range (12.4-18 GHz). The rectangular waveguide (WR-62) was used to measure the dielectric properties and magnetic properties of the samples. The results show the dielectric properties and conductivity of MWCNTs/PE composites is increasing with the MWCNTs filler increases. The real part of dielectric properties values increase from 5.5 to 26.6 with increasing the MWCNTs loading from 5 % to 15 %. The increasing of MWCNTs filler in the MWCNTs/PE composites does not effects on magnetic properties, the real part and imaginary part of magnetic properties are approximate to 1 and 0. The highest conductivity of 15 % MWCNTs loading is reach to 11.02 (S/m) at 18 GHz. Keywords: composites, dielectric properties, magnetic properties, conductivity

Electromagnetic properties of BaZn2Fe16O27/antimony-doped tin oxide composite absorbing materials by co-precipitation method

W-type barium ferrite (BaZn2Fe16O27)/antimony-doped tin oxide (ATO) composite absorbing materials were synthesized by co-precipitation method, using BaZn2Fe16O27 prepared by traditional solid method and SnCl4·5H2O, SbCl3 as main raw materials. The structure and morphology of the composites were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM). The result shows that BaZn2Fe16O27/ATO composites were obtained by co-precipitation method, and ATO nano-particles were coated on the surface of BaZn2Fe16O27 ferrite. The complex permittivity and complex permeability of BaZn2Fe16O27/ATO composite absorbing materials at the frequency range from 2 to 18 GHz were analyzed by vector network analyzer. It is indicated that ATO has strong dielectric property and ferrite shows superior magnetic performance. The result shows that the complex permittivity and dielectric loss of the BaZn2Fe16O27/ATO composite absorbing materials are higher than the pure ferrite, and the complex permeability and magnetic loss are higher than the pure ferrite and the pure ATO. When the mole ratio of BaZn2Fe16O27/ATO is 1:2, the minimum reflection loss is about −31.14 dB at 12.4 GHz, moreover, the absorption bandwidth reaches 9.6 GHz when RL is −10 dB in the measured frequency range of Ku-band.

Assessment of the Jason-2 Extension to the TOPEX/Poseidon, Jason-1 Sea-Surface Height Time Series for Global Mean Sea Level Monitoring

The Jason-2 (OSTM) follow-on mission to Jason-1 provides for the continuation of global and regional mean sea level estimates along the ground-track of the initial phase of the TOPEX/Poseidon mission. During the first several months, Jason-1 and Jason-2 flew in formation separated by only 55 seconds, enabling the isolation of inter-mission instrument biases through direct collinear differencing of near simultaneous observations. The Jason-2 Ku-band range bias with respect to Jason-1 is estimated to be −84 ± 9 mm, based on the orbit altitudes provided on the Geophysical Data Records. Modest improved agreement is achieved with the GSFC replacement orbits, which further enables the isolation of subtle (<1 cm) instrument-dependent range correction biases. Inter-mission bias estimates are confirmed with an independent assessment from comparisons to a 64-station tide-gauge network, also providing an estimate of the stability of the 17-year time series to be less than 0.1 mm/yr ± 0.4 mm/yr. The global mean sea level derived from the multi-mission altimeter sea-surface height record from January 1993 through September 2009 is 3.3 ± 0.4 mm/yr. Recent trends over the period from 2004 through 2008 are smaller and estimated to be 2.0 ± 0.4 mm/yr.

A new microwave absorber based on antimony-doped tin oxide and ferrite composite with excellent electromagnetic match

Antimony-doped tin oxide (Sn 0.9Sb 0.1O 2, ATO) and W-type barium ferrite (Ba 0.9Gd 0.1(Zn 0.3Co 0.7) 2Fe 16O 27) were synthesized by coprecipitation method and polymer adsorbent combustion method, respectively. The microstructures were studied using powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed that the pure ATO with spherical morphology and the pure W-type barium ferrite with hexagonal flake shape were prepared. The complex permittivity and complex permeability of ATO, ferrite and ATO/ferrite composites were analyzed by Agilent 8722ET. It was indicated that ATO had strong dielectric property and ferrite showed superior magnetic performance. An appropriate electromagnetic match was established when the composite microwave absorber contained 50 wt% ATO and 50 wt% ferrite. For the optimized microwave absorber, the maximum reflection loss (RL) was about −19.4 dB at 14.8 GHz. Moreover, the absorption bandwidth reached 3.6 GHz when RL was −10 dB in the measured frequency range of Ku-band.

The effect of multi-wall carbon nanotubes on electromagnetic interference shielding ofceramic composites

Multi-wall carbon nanotubes (MWCNTs)–3 mol% yttria-stabilized zirconia (3Y-TZP)(MWCNTs-3Y-TZP) composite was prepared by spark plasma sintering. The complexpermittivities of the composite have been measured in the Ku-band range (12.4–18 GHz)and it is found that both the real and imaginary permittivities of the composite increasewith the increasing content of MWCNTs. The effect of the content of MWCNTs on theelectromagnetic interference (EMI) shielding effectiveness (SE) of the composite has beenevaluated, and it is found that the EMI SE of the composite increases with the increasingcontent of MWCNTs. An EMI SE value as high as 25–30 dB has been achieved in theKu-band range for the composite with 9 wt% content of MWCNTs, indicatingthat the MWCNTs-3Y-TZP composite can be used as an effective EMI shieldingmaterial.

Comparison of the Ku-Band Range Noise Level and the Relative Sea-State Bias of the Jason-1, TOPEX, and Poseidon-1 Radar AltimetersSpecial Issue: Jason-1 Calibration/Validation

TOPEX/Poseidon is a well known success, with the operational altimeter (TOPEX) and the experimental one (Poseidon-1), providing data of unprecedented quality. However, there are two major differences between the TOPEX and Poseidon-1 radar altimeters on board TOPEX/Poseidon. The first is related to the estimated range noise; the second is linked to the sea-state bias (SSB) model estimates. Since the recent launch of the Jason-1 radar altimeter (also called Poseidon-2), we have been cross-comparing these three systems to better characterize each of them. Analyzing standard user products, we have found that Jason-1 is behaving like Poseidon-1 and thus shows the same observed differences when compared with TOPEX. A comparative analysis of their features was performed, starting from the on-board acquisition of the ocean return and ending with the ground generation of the high level accuracy oceanographic product. The results lead us to believe that the sources for these differences lie in both the waveform tracking processing and the presence or abscence of a retracking procedure whether on-board or on ground. Because Poseidon-1 and Jason-1 waveforms are retracked while TOPEX waveforms are not in the products distributed to the users, we have applied the same ground retracking algorithm to the waveforms of the three radar altimeters to get consistent data sets. The analysis of the outputs has shown that: (a) the noise level for the three radar altimeters is definitively the same, and (b) the source of the relative SSB between Jason-1 and TOPEX lies in the different behavior of the on-board tracking softwares.