In the millimeter-wave bands, the series-fed array antenna is facing a problem of large transmission loss and narrow bandwidth by using a high permittivity and large-loss tangent material. In this report, an air-layer is inserted in a LTCC waveguide of εr=6.6 and tanδ=0.013 to reduce the transmission loss. The reduction of the equivalent dielectric constant by the air insertion structure enhanc...

An investigation for the enhancement strategy of bandwidth performance and analysis of different types of losses associated with reflectarray antennas is presented in this paper. Studies are carried out using different commercially available dielectric materials with dielectric permittivity ( r) values ranging from 2.08 to 13 and loss tangent (tan ) ranging from 0.0003 to 0.025. The performance...

A new kind of double short strip and single-side micro strip type antenna architecture to develop a frequency reconfigurable annular slot antenna. The design and characterization of this "reconfigurable antenna (RA) annular slot" which was built on a microwave laminate TMM10i Rogers (permittivity=9. 8, loss tangent=0. 002), are presented in this paper. By increasing and decreasing the...

The increasing use of computer-based software packages for designing RF/microwave circuits requires very accurate data about dielectric properties of materials used in the design. This paper presents results of precise measurements of relative permittivity and loss tangent of alumina substrates and Fodel dielectric 6050 used in thick-film photoimageable technology for fabricating microwave doub...

An accompanying numerical simulation for obtaining field patterns, resonant frequencies, and the Q factor is proposed to evaluate the experimental conditions of complex permittivity reconstruction by the perturbation method and thereby improve its accuracy and flexibility. This approach is illustrated by analyzing the measurement of dielectric constant and the loss tangent of wet movie film in ...

The rectangular dielectric waveguide (RDWG) technique has been developed for the determination of the dielectric constant of materials from effective refractive index measurements in the Q and W bands. This paper describes the use of an optimization method in conjunction with the RDWG technique for the determination of both the dielectric constant and loss tangent of materials at Ka-Band. The e...

This paper presents a novel coplanar waveguide (CPW) dual pass band and triple pass band filter using the split-modes of the loaded stub square loop resonators. With the CPW feeding line, two micro strip stub resonators built on the rear sides are used to suppress resonance. We have designed our filter on the FR4 substrate (permittivity = 4. 4 and loss tangent=0. 02) with 20x50mm square and thi...

The variation of the monomeric friction coefficient of styrene butadiene copolymer (SBR) and natural rubber (NR) with various degrees of cure was analyzed. Samples with different levels of cure were prepared. Loss tangent measurements of the samples were performed by means of a damped torsion pendulum between 173 K and 373 K. Data were analyzed in the frame of the Kloczkowsky, Mark and Frisch m...

Magnetic resonance imaging (MRI) is a versatile tool widely used for diagnosing disease. It provides high resolution anatomical information of the human with excellent soft tissue contrast, obtained in a non-invasive manner, and can be used to guide treatments and surgeries through monitoring of temperature and visualization of tumors (1-5). More recent applications related to hyperthermic ther...

Taking advantage of the continuously improving, web-based learning systems plays an important role for self-learning, especially in the case of working people. Nevertheless, learning systems do not generally adapt to learners’ profiles. Learners have to spend a lot of time before reaching the learning goal that is compatible with their knowledge background. To overcome such difficulties, an e-l...