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This paper proposes a 1-bit linearly polarized reconfigurable transmitarray element with double-layer square slots. The theory for the cascaded 2-layer transmitarray element is presented first, and a dielectric thickness corresponding to a 30° phase delay is suggested as the layer separation in order to get a 180° phase difference with less than 1-dB magnitude loss. The double-layer square slot element...
This paper presents a novel inverse scattering method for biomedical application using microwaves. The method is established based on an evolutionary algorithm-particle swarm optimization method which can achieve accurate results for high dimensional problems. The use of time domain data allows multiple frequency selectivity. 2D FDTD simulations have shown that the method attains super-resolution...
A reflectarray antenna using flexible dielectric substrate is presented as a potential solution for high-gain THz antenna applications. The element phase compensation is achieved by appropriately tuning the flexible dielectric slab height. An equivalent circuit model is built to calculate the element reflection coefficient. A 30mm × 30mm square aperture dielectric reflectarray is then designed and...
A microwave imaging system for breast cancers using a miniaturized bowtie patch antenna array is presented in this paper. The antenna element was designed with resonant frequency of 2.57 GHz and return loss less than −15 dB. Thirty-six antennas were installed on the walls of the chamber. The back propagation method is used as the imaging algorithm. We demonstrate the capability of the proposed antenna...
A reflectarray antenna combines the advantages of reflectors and phased-arrays. Due to its low profile, low loss, and versatile radiation properties, it has emerged as a new generation of high-gain antennas. Meanwhile, terahertz (THz) technology, which locates between microwave and infrared, is a frontier of the state-of-the-art electromagnetic research. Recently, the concept of reflectarray has been...
In this paper four different reflectarrays, namely, metal-only block reflectarray, waveguide reflectarray, dielectric reflectarray, and traditional microstrip patch reflectarray, are designed as potential solutions for high-gain Terahertz antennas. For the purpose of comparison, all these cases are simulated using full-wave commercial software CST Microwave Studio with the same system configuration...
Dielectric reflectarray antennas are proposed as a promising low-loss and low-cost solution for high gain terahertz (THz) antennas. Variable height dielectric elements are used in the reflectarray designs, which allow for the use of low dielectric-constant materials. Polymer-jetting 3-D printing technology is utilized to fabricate the antenna, which makes it possible to achieve rapid prototyping at...
Dielectric reflectarray antennas are proposed as a possible low-loss solution for high gain THz antennas. A 3-D printing technology is utilized to fabricate the antenna, and numerical and experimental results are presented for a prototype operating at 100 GHz. This study shows that the proposed design approach is well suited for high gain THz antennas.
Microwave cavity with complicated structure and rubidium gas is studied by mode matching method. By calculating resonant frequencies of TE011 mode, main factors that influence resonant frequency is studied. In addition, the resonant frequency of TE011 mode is compared with commercial software (CST) results. The computed results show good agreement with CST simulations. It can be seen that this method...
Dielectric reflectarray antennas are studied in this paper as a possible low-loss and low-cost solution for high gain THz antennas. Variable height dielectric slabs are proposed for the reflectarray elements which allow for the use of low dielectric-constant materials for the design. A 3-D printing technology is utilized to fabricate the antenna, and both numerical and experimental results are presented...
The research on influence of geometry to dielectric frequency responses of oil-paper insulation was carried out in order to apply dielectric frequency response to diagnose the equipment more accurate thereof. According to the dielectric frequency response principle, the test system was established. The model of geometry structure of oil-paper was built by the dielectric theory. The dielectric frequency...
We investigate the Complex Natural Resonances (CNRs) of the malignant breast tissues with complex peripheries. The tissues are modeled as lossy dielectric objects with complex geometries which are expected to have different CNRs compared to those with smooth surfaces. Since the breast tissues are embedded inside inhomogeneous lossy breast medium, it is very important to ensure that a particular extracted...
In radar based confocal microwave imaging for breast cancer detection, recorded data are synthetically focused to a confocal point within the breast. This is the basis for both data-independent and data adaptive methods to form the breast image and can be enhanced by multistatic approach. This approach inherently assumes that the propagation velocity depends only on the average dielectric property...
This paper proposes a method that combines a data-independent beamformer with Matrix Pencil (MP) method to take into consideration the morphological properties of the malignant tissue. The simulated results have shown the resonant frequency and damping factor of complex natural resonance (CNR) are capable of differentiating the malignant tissue from other significant interferers such as benign lesions...
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