Cavity perturbation technique is widely used in the measurements of complex dielectric permittivity of materials due to its accuracy and ease of configuration. This paper presents the theoretical formulas for the evaluation of complex permittivity of materials using cavity perturbation technique with substrate integrated cavity resonators. With the proposed formulas, the use of various planar cavities is possible by taking into account the dielectric characteristics of the substrate in which the cavity is implemented. Simulations and measurements are performed on various dielectric samples to validate the proposed theory. The maximum deviation in the measured dielectric permittivity values is below 6% compared to the literature values. The implemented substrate integrated cavity is then analyzed in terms of sensitivity, showing a good performance.

A novel ultra‐wideband antenna solution to operate in the 4GLTE communications standard is proposed. The antenna has been built on flexible and very thin Kapton material, suitable for limited space wrist worn applications. The proposed antenna concept and construction is very simple, which is highly desirable in consumer goods with high production quantities. The antenna size is 127 × 25 × 0.13 mm and operates in the LTE bands 698–960, 1710–2170, and 2500–2700 MHz, having a 78% of usable bandwidth below −6 dB of return loss when mounted on human hand. The antenna exhibited great agreement between electromagnetic simulations in CST and measurements performed into 3D anechoic chamber with anthropomorphic forearm‐hand. The antenna is suitable to be manufactured using hybrid PCB technology with electronic circuits mounted on the top rigid section, and the asymmetrical tapered antenna design in the flexible sections. © 2017 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:777–783, 2017

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A wireless sensing system for the evaluation of the complex dielectric permittivity of solvent liquids is presented. Two sensing tags are proposed for testing of the samples. The first tag is based on a cavity resonator and the second makes use of the epsilon-near-zero effect. Both circuits are designed over the planar substrate-integrated-waveguide (SIW) technology, and operate at 4 GHz. A quartz capillary tube is used for the liquid measurements where only a small amount of sample volume is required. With the addition of planar antennas at the input and output of the sensors, the complete system is implemented for wireless sensing of the materials following the RF identification scheme. The cavity perturbation technique for SIW structures is applied for the dielectric liquid characterization. The proposed sensing tags and system have high potentials for low-cost wireless measurements and real-time monitoring applications.

In this article, a novel structure of a planar monopole antenna for Super Wide-band applications is proposed. The structure is based on the complementary Sierpinski triangle surrounded by two semi-circular sectors. The ground plane of the antenna has been modified including some slots to improve the operating bandwidth and coupling. The simulated and experimental results show that the antenna achieves a ratio impedance bandwidth >15:1 (from 1.68 to 26 GHz) for S 11 210dB.