Reflectors are a very important tools in counteracting the space borne or airborne SAR imaging systems. Because they can be used in the form of decoy and camouflage protection designs due to their high level RCS. The remarkable thing on this mission is that the SAR radar is capable of sending the wave to earth in any direction, with any incident angle and in any frequency band, and capturing sensitive areas. The design of such an all-directional, multi-band reflector, and wide angles reflector is very complicated because the reflex function depends on various parameters such as the dimensions, shape and material of the reflector, the frequency, the incident angle, and the polarization of the radiated wave. Existing refractors generally have a high RCS in a particular direction at a specific frequency and at a narrow viewing angle. In this paper, we will attempt to design a refractor of all directions, multiple bands and wide angles using shape structures.

In this paper, a four-band microstrip antenna using metamaterial structure is presented. The antenna proposed in this article, has an asymmetric structure and it is made up of two identical radiation elements and ground plane at the back. In this design, each radiation element consists of a reciprocating capacitor, which is attached to a slotted triangular acetate at the end. The proposed antenna has a miniature dimension of 10×15 mm2. Also the proposed antenna has four resonances in frequencies of 3. 19 GHz (1. 25%), 6. 22 GHz (10. 74%), 7. 18 GHz (5. 19%) and 9. 12 GHz (4. 52%). Pattern and gain of the antenna are acceptable at resonant frequencies and the good consistency between the test result and the simulation confirm the accuracy of the antenna design. The proposed antenna is made and tested in the antenna laboratory. The results of the measurements are presented in the paper. Good consistency between test and simulation results confirms the accuracy and efficiency of the proposed multirole microstrip antenna design.

This paper presents a new approach for the design of a Multiband uniplanar CPW-fed monopole antenna. The antenna consists of a fork like monopole strip to which is added an inverted U-shaped strip. The three branch fork like strip can create three resonant bands within the WLAN range while the placement of the inverted U-shaped strip provides a better impedance matching for the lowest resonant frequency band. Loading slot on the top of the U-shaped strip with asymmetric arms can add two further resonant frequency bands. This antenna can cover the frequencies of PCS, WiMAX and WLAN applications along with the major part of the C band. A prototype of the antenna is fabricated and tested. A good agreement is found between simulated and measured results.

Adaptive algorithms play an important role in order to improve performance of diffusion distributed network. In comparison of diffusion Normalized least mean square algorithm, family of diffusion subband algorithms have faster convergence rate when the input signal is highly correlated. This paper solves the problem of distributed estimation in the diffusion networks based on improved Multiband-structured subband adaptive filter (IMSAF) and diffusion improved Multiband structured subband adaptive filter (DIMSAF) is established. In proposed algorithm, convergence behavior improved due to using several input projections instead of single vector of input data. In addition, when the projection order is increased, the convergence rate of the proposed algorithm improves. The validity of the DIMSAF in comparison of DLMS, DAPA, VSS-DAPA and DRLS algorithms is demonstrated by several computer simulations. The results show fastest convergence rate.

As an important control element in steam heating piping systems, the safety and stability of inverted bucket steam valves determine the reliable operation of the system. Therefore, it is necessary to investigate the acoustic mechanism of inverted bucket steam valves. Aiming at the difficulty of numerical simulation in accurately predicting the aerodynamic noise of inverted bucket steam valves, this paper proposes a new method for simulating the aerodynamic noise of inverted bucket steam valves based on Multiband analysis (LES). The flow field of the inverted bucket steam valve is numerically simulated using the LES method to obtain wall pressure pulsation information and fluid velocity pulsation information, which are used as excitation sources for acoustic simulation. The characteristics of dipole and quadrupole sound sources were obtained by applying the FW-H method and experimentally verified. The results show that a new multifrequency band analysis method for inverted bucket steam valves is effective by comparing the numerical simulation results, in which the dipole source dominates in the low-frequency band, in the medium frequency range, the quadrupole source outperforms the dipole source, but in the high frequency range, the quadrupole source is dominant. The experimental results are in good agreement with the simulation results, and the correctness of the numerical simulation is confirmed by the fact that there is less than a 3% difference between the findings of the numerical simulation and the experimental data.

In this paper, a novel planar hybrid Multiband antenna formed by a loop-type antenna, a monopole slot antenna, and a coupled planar monopole antenna for the mobile phone is proposed. The loop-type antenna comprises a driven monopole and a coupled strip that printed on the other side of the substrate and short-circuited to the ground. The 0.5l and 1.0l mode of the loop-type antenna are excited. Therefore, the 0.5l mode of the loop-type antenna forms a wide bandwidth of 326 MHz to cover the GSM850/900 operation and the 0.25l mode of the monopole slot antenna, the 1.0l mode of the loop-type antenna, and the 0.25l mode of the coupled monopole antenna provide a wide bandwidth of 1181 MHz to cover the GPS/DCS/PCS/UMTS/WLAN2.4/WiMAX operation. Finally, the 0.5l mode of the coupled monopole antenna forms a wide bandwidth to cover the WLAN5.2 operation. Moreover, the hybrid antenna occupies a compact area of 16.5´45 mm2 and it has good radiation characteristics over the operating bands.

Nearly simultaneous Multiband monitoring of blazars is very limited and most studies reported in literature are conflicting, too. Although optical variability on intra-night timescales is now a well-established phenomenon for blazars, its relationship to long-term variability remains unclear. Possible clues could come from monitoring the optical spectrum for correlation with brightness. The presence or absence of bluer color in blazar color index, when its luminosity is increased on intra-night and inter-night timescales, can provide interesting clues to the origin of blazar variability from hourly to much longer timescales. Luminosity of blazars varies at all wavelengths over a variety of timescales. Various models have been proposed to explain blazar variability. However, the mechanism responsible for variability is not conclusively understood. One factor which can discriminate the various variability models is that of color (spectral index) variations of blazars. This factor may help to better understand the mechanism of blazar variability. Therefore, it was initially proposed, by the second author of this paper to the OHP observatory, to carry out quasi-simultaneous Multiband monitoring of one of the brightest blazer, Mrk180. Fortunately, it was accepted by the scientific team of the observatory and the 1.20m telescope time was allocated to the project from 23 to 28 April 2009. Because of the weather conditions, we could only monitor this blazar for three nights. Raw data processing and data reduction were performed using the standard system of Europe Southerner Observatory, ESO-MIDAS. We considered two reference stars and measured the magnitudes of the reference stars and the blazar Mrk 180 and then plotted the light curves and the color index diagrams. The light curves showed the optical variations of the blazar. The maximum amplitude value of its variations was 0.185 mag for the V filter. Investigating the blazar color index shows its variations on intra-night and inter-night timescales.

In this manuscript, replacing traditional antennas with biodegradable PLA substrates aims to reduce e-waste in today's technologically advanced age. This work achieves its objectives by designing the miniaturized (56 x 56 x 1.6) mm3 hexagonal patch antenna with partial ground (18.2 x 52) mm2 and incorporating complementary split ring resonators (CSRRs) in the HFSS (High-Frequency Structure Simulator). This innovative approach combines unconventional antenna design with metamaterial technology to enhance antenna performance, making it flexible, lightweight, and suitable for multi-band applications. An evaluation of PLA compared to other substrates revealed that PLA is more suitable for its eco-friendliness, and the simulation result is also satisfactory for bandwidth, return loss, VSWR, directivity, efficiency, and other parameters. Additionally, the integration of taffeta fabric as a conductive patch material provided elasticity and enhanced wearability. Using this unique method, the proposed antenna resonates at Multiband frequencies of 2.6 GHz, 8.6 GHz, 10.5 GHz, 12.4 GHz, and 15.3 GHz, which gives return losses of -26.84 dB, -22.16 dB, -29.87 dB, -39.43 dB, and -26.35 dB, respectively. In addition to its biocompatibility and achievement of the SAR threshold, the antenna serves as a long-term solution for multi-band wireless applications. This further advances the realm of environmentally friendly wearable technology.