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At THz frequencies, indium antimonide (InSb) exhibits a negative permittivity, leading to the excitation of a surface plasmon resonance (SPR) [1]. In this work, we investigate the transmission characteristics of THz filters with the localized SPR excited around InSb square patches using the three-dimensional finite-difference time-domain method. First, we use an FR4 substrate with a thickness of 500...
An inverted LFFL card antenna (InvLFFL) is designed as a quadband antenna, where target frequency bands are 1.7 GHz, 2.45 GHz, 3.5 GHz, and 5.2 GHz bands. The InvLFFL is composed of a modified inverted L element, two inverted F elements, and a parasitic inverted L element. The design is performed based on one-quarter wavelength resonance at each band. The InvLFFL has a 4.6% bandwidth around 1.7 GHz,...
An antenna composed of a fed metaloop and a parasitic metaloop is presented. The antenna characteristics for this double metaloop, including the radiation pattern, axial ratio, gain, and VSWR, are compared with those for a single metaloop where the parasitic metaloop is removed. The double metaloop antenna has a smaller cross-polarized radiation component than the single metaloop, leading to a wider...
This paper presents the radiation characteristics of a low-profile circularly polarized loop antenna that has a left-handed property. The antenna height is set to be small (less than 0.03 wavelength). The gain, axial ratio, radiation efficiency, and VSWR are discussed.
A Kraus grid array antenna (K-GAA) and a rhombic grid array antenna (RGAA) are investigated as frequency beam-scanning antennas. The fundamental radiation characteristics, including the beam direction and gain, are discussed. The resonance for the RGAA is reduced by adding perturbation elements to the hexagonal loops, thereby enhancing the gain bandwidth.
A dual-band counter circularly-polarized (CP) loop antenna is proposed, where the antenna has a single feed point. Analysis is performed to reveal the effects of a lossy antenna structure on the radiation characteristics. The amount of reduction in the maximum gain and radiation efficiency due to the losses is revealed.
A complete set of equations of the LOD-BOR-FDTD has been derived for the analysis of not only fundamental but also higher-order modes with respect to the rotational direction. The number of arithmetic operation is significantly reduced in comparison with the ADI counterpart. Numerical results of a circular cavity resonator show that the resonance frequency is efficiently obtained particularly for...
The unconditionally stable locally 1-D (LOD) scheme is used to develop an efficient implicit body-of-revolution (BOR) finite-difference time-domain (FDTD) method. In the LOD-BOR-FDTD, the number of arithmetic operations of the resultant finite-difference equations is significantly reduced, when compared with the alternating-direction implicit (ADI) BOR-FDTD. Numerical results of circular cavity resonators...
A star patch antenna with four feeding points is proposed for generation of four tilted beam patterns in four different space quadrants. Hence, when these feeding points are excited one by one the whole space in front of antenna can be scanned. For the same physical dimensions in comparison to a star strip antenna, the star patch antenna has a 30 percent lower resonating frequency. The gain and AR...
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