A review paper concerning wide-band and ultra-wideband (UWB) antennas used for wireless communication purposes in terms of the materials as well as a numerical analysis is presented. These antennas which are taken into account are listed as wide-band microstrip antenna, wide-band monopole antenna over a plate, wide-slot UWB antenna, stacked patch UWB antenna, taper slot (TSA) UWB antenna, metamaterial (MTM) structure UWB antennas, elliptical printed monopole UWB antenna, and flexible wearable UWB antenna. The antennas’ performance is compared based on their size and how they can be applicable for portable communication device applications. This review paper furnishes a proper direction to select varieties of figures in terms of impedance bandwidth, gain, directivity, dimensions, time domain characteristics, and materials affecting these antenna’s characteristics.

This article presents the design of a droplet shape ultra-wide band antenna for imaging of wood. The proposed antenna is designed on PTFE substrate with a dielectric constant of 2.55, loss tangent of 0.001- and 2.4-mm thickness. The antenna is loaded by a stub to resonate at lower band frequency, strip loading at the back, and a chamfered ground to increase the bandwidth. Despite having miniaturized dimensions of 15 mm × 15 mm, it shows better results compared to recent studies. The simulation results depict a good ultra-wide bandwidth from 3.26 GHz to 20 GHz, and 21.5–25 GHz; Besides, the proposed antenna has two bands at 1.25–1.35 GHz and 1.7–1.81 GHz. In addition to that, the antenna achieved a maximum gain of 5.69 dB and directivity of 7.3 dBi. The measurement results of S-parameters transmitted and received signals performed in air, plywood, and high-density wood show a good agreement with the simulated results. In addition, the measured results illustrate a good isolation and uniform illumination among arrays as well as the received signals’ shapes do not change in different environments, but only the amplitude. Hence, the proposed antenna seems to be adequate for microwave imaging of wood.

The assessment of moisture loss from meat during the aging period is a critical issue for the meat industry. In this article, a non-invasive microwave ring-resonator sensor is presented to evaluate the moisture content, or more precisely water holding capacity (WHC) of broiler meat over a four-week period. The developed sensor has shown significant changes in its resonance frequency and return loss due to reduction in WHC in the studied duration. The obtained results are also confirmed by physical measurements. Further, these results are evaluated using the Fricke model, which provides a good fit for electric circuit components in biological tissue. Significant changes were observed in membrane integrity, where the corresponding capacitance decreases 30% in the early aging (0D-7D) period. Similarly, the losses associated with intracellular and extracellular fluids exhibit changed up to 42% and 53%, respectively. Ultimately, empirical polynomial models are developed to predict the electrical component values for a better understanding of aging effects. The measured and calculated values are found to be in good agreement.

This paper presents the design of an elliptical shape ultra-wide band antenna for imaging of wood. The antenna is constructed comprising an elliptical shape of patch loaded by a stub to resonate at lower bands, strip loading at the back, and chamfered ground. Despite having miniaturized dimensions of 20 mm × 20 mm, the proposed antenna shows better results compared to recent studies. The simulation results depict a good ultra-wide bandwidth from 2.68 to 16 GHz, and 18.2–20 GHz. Besides, the proposed antenna has two low-frequency bands at 0.89–0.92 and 1.52–1.62 GHz, maximum gain of 5.48 dB, and maximum directivity of 6.9 dBi. The measurement outcomes are performed in air, plywood, and high-density wood and show a good agreement with the simulated results done using electromagnetic simulator CST. In addition to that, the measurement results of S-parameters, transmitted and received signals show a good agreement with the simulated results. Besides, the measured results illustrate a good isolation and uniform illumination among arrays as well as the received signals' shapes do not change in different environments, but only the amplitude. Hence, the proposed antenna seems to be adequate for microwave imaging of wood.

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shown in Figure 7 with the simulation data at the same time. The performance summary is shown in Table 1.Core structures of the dual-band SIW filter are the CSRRs and CSRs. Relatively speaking, the influences of other geometrical parameters are not obvious. So that the filter has a potential to be much smaller. As shown in the photograph from Figure 8, length of the SIW is greatly reduced, and the taper microstrips are removed. After adjustment and optimization, its geometrical parameters are: l SIW 5 9 mm, w SIW 5 12 mm, r via 5 1 mm, w via 5 2 mm, w 2 5 1.2 mm, l 1 5 3 mm, l 3 5 1.9 mm, a 1 5 0.28 mm, b 5 5.2 mm, d 5 0.82 mm, g R3 5 0.3 mm u 1 5 0.22 mm, u 2 5 0.095 mm, h 5 7.5p, t 5 3.149 mm. The geometrical size of the simplified filter is 0.118k 0 3 0.184k 0 , where k 0 is the free space wavelength at the center frequency of lower passband. Furthermore, the performance of the filter does not decline with structure simplification, as shown in Figure 8, and Table 1.Due to processing inaccuracy, there are slight differences between the results of measurement and simulation. But overall, most of them are consistent, proving that the theoretical analysis of the design is correct. CONCLUSIONA new approach to design the dual-band SIW filter is proposed in this article. By modifying the CSRRs and loading them into the SIW with the CSRs together, the compact dual-band filters perform well. The interaction between the CSRRs and CSRs is discussed, indicating the potential on the combination of those two right/left-hand structures. After simulation and optimization, the proposed dual-band SIW filters are fabricated using normal PCB process. From the results of measurement, it can be seen that the proposed filters have good frequency selectivity, and excellent band rejection, which are consistent with the simulation results.ABSTRACT: This letter describes a size-independent effective permittivity of biological tissues, using microstrip ring resonator (MRR), to evaluate the moisture content more effectively. As permittivity is depends on material density, the optimum sample size where further size variations will not change the effective permittivity are identified. Using simulation and experimental results it is found that, a sample having thickness more than 9% of substrate height (t sub ) and width greater than 18.3% of guided wavelength (k g) shows size-independent effective permittivity. Both simulation and experimental results are in good agreement (within 3%). These findings allow more effective characterization of muscles according to their moisture content. V C 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:4-9, 2016; View this article online at wileyonlinelibrary.com.

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