X-band applications

In this paper, a high gain narrow band array of rectangular microstrip patch antennae is proposed. Every array element is rectangular in shape. FR-4 and Rogers-3006 material with dielectric constant 4.4 and 6.51, loss tangent of 0.002 and height 1mm have been used as substrates. Microstrip lines are used as feed lines to substrate. The proposed design of 8x1 patch array antenna using ROGERS-3006, gives better results in comparison with FR-4 in microwave application. The operating frequency is considered as 10 GHz. The patch array has been targeted for the application as sensor, where high gain, narrow bandwidth and higher directivity is needed, which are simulated and compared in the proposed research.

Microstrip antennas are the most common antennas widely implemented in different communication systems due their small size, low profile and conformity to planar, and non-planar surfaces. In this research work, the design and simulation of an innovative single element inset-fed Rectangular Microstrip Patch Antenna (RMPA) for X-band application is presented. The proposed design used an operating frequency of 10 GHz, a Rogers RO4350 substrate with dielectric constant of 3.66, and a substrate height of 31 mil. The antenna performance characteristics such as return loss, bandwidth, VSWR, gain, directivity, beamwidth, and radiation efficiency were obtained in the simulation. The simulation results showed that the designed antenna resonated at 10 GHz, with a return loss of -19.61 dB, bandwidth of 226.2MHz, VSWR of 1.82, gain of 6.58 dBi, directivity of 6.83 dBi, a wider beamwidth of 115.2°, and an antenna efficiency of 94.2%. The novel antenna can be embedded in wireless devices for commercial WLAN and WiMAX applications and onboarding on radar and satellite wireless communication systems for various surveillance and communication purposes.

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Gallium substituted Z-type hexagonal ferrites with chemical composition Sr3Co2-xGaxFe24O41 (x = 0.0,0.4, 0.8, 1.2, 1.6, and 2.0) were successfully synthesised in air at 1200 °C for 5 h using the sol-gel auto-combustion technique, in order to investigate the effect of gallium substitution on structural, magnetic and dielectric properties. X-ray Diffraction (XRD) analysis of all samples reveals the formation of mixed hexaferrite phases, with Z ferrite as the major phase (72–90%).The average crystallite size of heated powders was found to be in the range of 21–40 nm. The saturation magnetisation decreases after gallium substitution, with the lowest values of 64 Am2 kg−1 for composition x = 1.6, which also has the highest value of coercivity (28.3 kA m−1). Nevertheless, all were soft ferrites, with Hc between 3.4 and 28.3 kA m−1.The Mr/MS ratio of all samples was found to be less than 0.5, suggesting that all the compositions possess multi-domain microstructures. Mössbauer spectroscopic analysis confirmed that the Fe ions were found in the 3 + high spin state for compositions below x ≤ 0.4, whereas ∼1.5% of the Fe ions were converted into Fe2+ high spin state beyond x ≥ 0.8 compositions, as Ga3+ began to substitute for Fe3+, forming Fe2+ in the cobalt positions. The average hyperfine magnetic field (<Hhf>) was found to be decreased with Ga-substitution. Dielectric parameters such as dielectric constant and loss factor were studied as a function of frequency, and their results show normal behaviour for ferrimagnetic materials. In complex measurements at microwave frequencies (8 GHz–12.5 GHz, the X-band), all samples had a real permittivity of around 8–14. For sample x = 2.0, a dielectric resonance peak was observed around 12.15 GHz. All showed a real permeability of around 1.0–1.4 over the frequency of 8 GHz–12.5 GHz range, and ferromagnetic resonance (FMR) was observed in x = 0.0 and 2.0 samples, at around 11 and 12 GHz, respectively. This suggests that the prepared samples can be used as microwave absorbers/EMI shielding at specific microwave frequencies. The co-existence of FMR and dielectric resonance at the same frequency of 12.15 GHz for x = 2.0 could lead to the coupling of these resonances and the development of potential metamaterials.

This article proposes a low profile planar monopole antenna on flexible substrate. The antenna is designed with an elliptical slot inserted in a rectangular patch by utilizing the coplanar waveguide (CPW) feeding technique on a polyimide substrate. The proposed antenna operates within 7-14 GHz (S 11 < À 10 dB) with a minimum return loss is observed as low as-58 dB by simulation, whereas the entire X-band is covered by the-20 dB bandwidth while maintaining an excellent VSWR of almost 1. Also, the antenna exhibits an average gain of 4 dBi while the average radiation efficiency is 92%. The maximum SAR of the proposed antenna for 1 g mass is below 1.0 W/Kg throughout the entire bandwidth. To observe flexibility, four different bending conditions of the antenna have been analyzed. For experimentation, the antenna has been realized as a prototype by using a low-cost fabrication process. The measurement reveals that the prototype has a À10 dB bandwidth of 5.4 GHz. During In-Vivo test, over the variation of 0 $ 3 mm distance between the antenna-prototype and the human chest/chicken breast tissue, the best performance is obtained at 3 mm in terms of the return loss. One of the significant features of the proposed design is its measured average and peak gain of 4.4 dBi and of 6.33 dBi respectively with a measured average efficiency of 65%. The proposed antenna has a compact size of 13  13 mm 2 (0:35k g  0:35k g), and its performance remains nominally constant even under different bending conditions which makes the antenna suitable for biomedical imaging applications. A new figure-of-merit has been introduced to evaluate the overall performance based on different antenna key parameters. The fabricated antenna would contribute to the future biomedical research by utilizing X-band frequencies.

In this study, an electromagnetic wave 8-12 GHz X band microwave was utilized to detect various types of damage in a woven fabric composite structure. Damages, such as cracks, delamination, bubbles, and voids, were synthesized artificially in accordance to ASTM D2734. Variable thicknesses of composite structure were also analyzed, and the influence of defect on the transmitted signal was investigated. Network analyzer (ENA5701C) in Xband was utilized for this investigation. Detection was based on the changes in the electromagnetic properties, such as permittivity and permeability, and the reflection and transmission to microwaves were based on standard samples. These were implemented for each case of defect selected for this study. Experimental tests revealed that damage in the transparent glass/epoxy composite can be recognized clearly. Particularly, sample thickness was detected when the microwave was applied. This testing method can be considered an inline operation and non-destructive testing for such composites, especially during fabrication.