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From the Shannon-Hartley theorem, the channel capacity depends on the received S/N (signal to noise ratio) and the data streams in communication system. The S/N and data streams depend on the performance of antenna. In order to improve the channel capacity in digital data communication, reconfigurable antennas play an important role for the communication system.
In this research, we investigated the surface-wave dispersion characteristics in a grounded dielectric slab. Due to the phase match between the plane wave in a high dielectric constant medium and the surface wave supported in the grounded dielectric slab, the plane wave couples into the surface wave and is absorbed by the lossy substrate accordingly. By progressively changing the incident angle and...
In this paper, a low-profile dipole array antenna for on-body communications in wireless body area network (WBAN) is proposed. The proposed antenna consists of eight planar dipole antenna elements. To obtain the monopole-like radiation pattern, eight dipole elements are placed symmetrically around z-axis. The simulated 10-dB return loss bandwidth of the antenna is wide enough to cover the 2.45 GHz...
This paper proposes new reflectarray elements for dual-polarization wideband use. These elements provide low cross polarization property and almost linear phase property for the frequency, thereby achieving the desirable reflection phase over the wide frequency range. To verify effectiveness of the proposed elements, a reflectarray with offset feed is constructed by them, and also is wideband frequency...
This paper presents design of a microstrip antenna array fed by transverse slots on a broad wall of the rectangular waveguide with standing wave excitation for linear polarization parallel to the axis. A series-fed two-element microstrip antenna array on a dielectric substrate excited by a transverses slot of the waveguide is used as an element of the proposed array. In this paper, radiation power...
This paper presents a new analytical approach for multimode horn antennas with coaxial grooves arbitrarily loaded along the antenna axis on the taper wall. Discontinuities between such coaxial grooves are analyzed by the mode-matching method, and then the scattering matrix of a whole antenna is derived from cascade connections of the matrixes expressing the discontinuities. The scattering matrix obtained...
This paper presents a low-profile, horizontally polarized and compact printed antenna radiating parallel to the ground plane. The proposed antenna consists of a small inner feeding loop, a coupled split ring element and a ground plane. The dimension of the proposed antenna is 45 mm × 50.5 mm × 11.6 mm (0.138λ0 × 0.155λ0 × 0.036λ0). From the results, the −10-dB |S11| of the antenna covers the 920-MHz...
A novel band-reconfigurable antenna with stable unidirectional radiation patterns is presented for cognitive radio applications. One wideband mode based on a magneto-electric (ME) dipole and four narrowband modes based on a length-reconfigurable thin dipole are achieved for operation between 0.83 to 2.16 GHz. PIN diodes are used as switches for choosing different operating modes. The ME dipole technology...
Characteristic modes analysis of a 4G cellular antenna which operates in LTE, GSM, DCS, PCS and 2.4GHz WLAN standards for an eyewear wireless devices is presented. In previous work, the antenna was designed as capacitive coupling element feeding type, using a printed circuit board (PCB) of FR4 substrate. The antenna operates at 700–960 MHz and 1.7–2.7 GHz frequency bands and complies with all the...
This paper presents a simple multi-band improvement technique for a linear inverted-F antenna designed for mobile devices using only one shorting strip to obtain good impedance matching at many different frequencies. Our results show that the proposed technique is very straightforward, and can be simply applied to multi-band design of inverted-F antennas, so that it is possible to both control easily...
In this paper, we propose the use of the modified nodal analysis (MNA) method to rederive cavity-mode equation of PCB power-bus structures with discrete capacitors. In some frequency, it shows impedance inaccuracies in the traditional double summation to calculate the transfer impedances for the studied PCB power-bus structures with discrete capacitors. Using our proposed method, we not only achieve...
For the first time, a 3-dimentional (3-D) transmission line dual-mode resonator is proposed by using the low temperature co-fired ceramic (LTCC) technology. The proposed dual-mode resonator is reasonably folded in both vertical and horizontal directions for constructing a miniaturized bandpass filter (BPF), which overcomes the vital shortcoming of large circuit size of the LTCC distributed-element...
This paper presents an automatic impedance-matching algorithm that can sequentially realize a simultaneous conjugate-matching state for all the elements in an N-element array antenna. The analytical results show that the converged solution obtained from the proposed algorithm agrees well with the solution calculated by the analytical deterministic equation, confirming the validity of the proposed...
This paper presents a Substrate Integrated Waveguide (SIW) directional coupler with required phase-difference at the output ports. In order to verify the feasibility of this design method, a 45° and a 90° SIW coupler are designed, simulated and optimized. The results of simulations have shown the great performances over a broad operational bandwidth.
It is conceivable that changing the propagation characteristics of the environment actively in some ways enables us to improve transmission performance of wireless communication channel. We call such method “Active propagation control” (APC). In this paper we analyze the channel capacity of multiple-input multiple-output (MIMO) transmission system in order to show the fundamental effectiveness of...
MIMO radar and Khatri-Rao (KR) product virtual array are the methods for increasing angular resolution of the array radar. The KR product is not suited to radar because KR product needs data property of uncorrelated wave incidence. However, when we extract responses of moving targets having different Doppler frequencies by Doppler filtering, the KR product array works almost properly because their...
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