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This paper proposes small CRPA arrays with high-dielectric ceramic superstrates for dual-band operation. Each array element consists of inner and outer microstrip rings printed on a high-dielectric substrate, and a hybrid chip coupler is used for quadrature excitation to achieve circular polarization. The superstrates with high relative permittivity are designed to have a cylindrical shape and are...
This paper proposes a small CRPA array with frequency-insensitive properties. The array consists of seven elements, and each element is composed of upper and lower circular loops that are designed to resonate at 1.575 GHz and 1.227 GHz, respectively. The lower loop is fed by the hybrid chip coupler, and the upper loop is electromagnetically coupled for a frequency-insensitive feeding mechanism. Due...
We provide the transmittances through periodic slits for perfect and real conductors as functions of the thickness of plates. In the case of a real metal, resonant transmission effects are observed. At low terahertz frequencies, the electromagnetic transmission properties are very similar to the cases of the perfect conductor, while the properties of high terahertz frequencies are changed compared...
The distribution of the roots in point and discretized continuous spectra is investigated as functions of terahertz frequencies in a metal-insulator-metal waveguide. The shape of the roots distribution affects the various electromagnetic wave transmission through the metal slit. The lossy transmittances in metals are found compared to no loss with a perfect conductor.
The behavior of power transmission of a normally incidence plane wave with TM polarization through subwavelength slits on Ag and Au plates from 1.2 THz to 200 THz is investigated for various plate thicknesses. The transmission patterns versus plate thickness by using mode matching technique are contrasted to those of a slit on perfectly conducting plate. The transmission physics at low frequency is...
This paper proposes the design of antipodal Vivaldi antennas using the kernel regression method. The kernel regression is applied for training a cost function model to predict the next sample with improved cost values, and the information of the predicted sample is employed to re-train the model. This process is repeated until the cost value converges to our design goal. The shapes of the tapered...
This paper proposes a periodic structure to improve isolation using ferrite materials for small controlled reception pattern antenna arrays. The periodic structure is composed of metal and ferrite plates with high permeability, and the ferrite material is used as a replacement of the perfect magnetic conductor in the soft surface to reduce the size of the corrugated geometry. This structure improves...
The behavior of power transmission of a normally incidence plane wave with transverse magnetic polarization through subwavelength slits on silver and gold plates at 30 terahertz is investigated for various slit widths and plate thicknesses. The analysis is performed based on a rigorous mode matching technique which is appropriate to this geometry. The transmission patterns versus plate thickness in...
This paper proposes the design of microstrip patch antennas to minimize the polarization mismatch. The proposed antenna consists of a circular radiating patch and multiple parasitic elements. The number, length, and angular positions of the parasitic elements are adjusted to vary the antenna polarization as well as the orientation of the main axis. To demonstrate the feasibility, we design two sample...
This paper proposed the test setup for performance evaluation of an FMCW radar. The test setup includes multiple targets with different velocities, which represents the boundary of a certain detection region. The surrounding environments, such as the position and direction of the antenna arrays and ground conditions are also included in the test setup. The metric for evaluation of the detection performance...
This paper proposes the design of an arc-shaped patch antenna for GPS arrays that is composed of an arc-shaped patch with two parasitic elements. The antenna is then arranged in a three-element circular array with an inter-element spacing of about a quarter wavelength, and the isolation characteristics are further improved by inserting a slot to the ground plate. Detailed design parameters are optimized...
This paper proposes the optimum array configuration that improves the null steering performance for controlled reception pattern antenna (CRPA) systems. The proposed array is composed of a center reference element and six auxiliary elements, and its array pattern is adaptively steered to mitigate the interference effect in conjunction with a constraint least-mean-square (LMS) algorithm. Then, the...
This paper proposes a deterministic method of array configurations using an objective function for accurate DOA estimation in a wide frequency range. The objective function is defined to describe appropriate baseline distributions of an 8-elemnt circular array for the max-min frequency ratio of 6:1 and used to finds the most similar distributions among a number of random array configurations. The...
A dual-band printed dipole antenna with wide-beamwidth radiation patterns is introduced for 2.4/5 GHz bands wireless local area network access points. A printed dipole is designed at the center of circular ground plane and fed by a novel integrated balun consisting of a curved microstrip-line and a circular slot to allow broadband operation. An angled dipole and two vertical copper plates on the ground...
In this paper, a high gain printed quasi-Yagi antenna is introduced for 60 GHz wireless applications. The antenna is fed by a novel microstrip-slotline transition consisting of a curved microstripline and circular slot in order to allow wideband characteristics. A corrugated ground plane is employed as a reflector for improving gain and small gain variation. The proposed antenna has an impedance bandwidth...
This paper describes a wideband double dipole quasi-Yagi antenna fed by a microstrip-to-slotline transition. The transition feed consists of a microstrip radial stub and a slot radial stub, each with the same angle of 90°, but with different radii to achieve wideband impedance matching. Double dipoles with different lengths are utilized as primary radiation elements to enhance bandwidth and achieve...
In 1959, Wheeler published the theory of the radiansphere, which is the boundary between the far and near field with a distance of λ/2π from an antenna. The inside field of the radiansphere is mainly involved in the loss power and stored energy, while the outside field is concerned with the radiation power. Wheeler's theory is that the radiation power can be removed from the antenna without disturbing...
This paper proposes a double-faced glass-integrated antenna for military FM radio communication on aircraft. The proposed antenna, consisting of a feed, a parallel strip, and a radiator, uses both sides of the window. The feed strip and the parallel strip are directly printed on the inner surface, while the radiator is printed on a thin transparent film to be placed on the outer surface. This allows...
In this paper, we propose a simple U-shaped radio-frequency identification (RFID) tag antenna with an isotropic radiation characteristic for stable operation of an RFID system. The antenna is composed of a U-shaped half-wavelength dipole and a rectangular-shaped feed. The feed is connected at the bottom of the dipole for conjugate impedance matching with a commercial tag chip. The gain deviation of...
The effects of a cavity structure on the characteristics of a half E-shaped patch antenna printed on a low-permittivity substrate with an air gap were investigated. The addition of the cavity structure increased the impedance bandwidth, improved the gain, and reduced the backward radiation of the antenna.
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