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Electromagnetic analysis for microstrip antenna and packaging structures is formulated by volume-surface integral equations (VSIEs). The conducting microstrip and ground are described with SIEs, while the dielectric substrate is governed by volume integral equations (VIEs), and they are coupled to each other to form VSIEs. Using VIEs instead of SIEs for dielectric substrate can improve the conditioning of system matrix related to the multiscale property of antenna and packaging structures. The VSIEs are usually solved by the method of moments (MoM) with well-designed basis functions defined over conforming meshes, resulting in much inconvenience of implementation. We propose a mixed approach to solve the VSIEs by combining the traditional MoM for the conducting part and a point-matching scheme for the dielectric part together. The approach uses cuboids to discretize the dielectric substrate and does not require conforming meshes between the conducting and dielectric parts. Also, the approach considers the thickness of metallic microstrip and ground, which is usually neglected. Typical numerical examples are presented to demonstrate the proposed approach, and its effectiveness has been verified.

In this paper, the well-known high frequency structure simulator (HFSS)is used to design an ultra-high-frequency (UHF)radio-frequency-identification (RFID)tag antenna with a paper substrate. With the continuous development of RFID technology, various factors of designing RFID tags have been investigated such as the substrate material, tag shape, working frequency band, and impedance matching. In the design of passive tag antenna, the impedance matching, broadband, and miniaturization are the main difficulties. We use a special structure to improve the performance of passive tag antenna and an UHF RFID tag antenna with a paper substrate is proposed for near-field applications. The tag antenna uses a matching network to achieve the impedance matching and employs a first-order Hilbert fractal structure to reduce the size. The overall size of the antenna is 63.6mm⨯25mm and the operation band is from 881.9 MHz to 962.2 MHz which can cover the UHF RFID bands of many countries. Its good performance is verified by HFSS simulation and measurement.

In this paper, we investigate the resonant frequency of the antenna with the mechanical deformation and a wireless rectangular patch antenna is presented and optimized. The simulation result indicates a good linearity between the resonant frequency shift and mechanical deformation in three directions, which are longitudinal, transverse and oblique directions, respectively. In addition, in order to make it more accurately in many applications, approximate relationship among these three directions has been given in this work.