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This paper presents a Compact Dual-Circularly Polarized Corrugated Horn with Integrated Septum Polarizer in the X-band. Usually such a complicated structure would be fabricated in parts and assembled together. However, exploiting the versatility afforded by Metal 3D-printing, a complete prototype is fabricated as a single part, enabling a compact design. Any variation due to mating tolerance of separate...
This paper proposes a new rectangular horn for orthogonal polarized elliptical beams. This consists of two sectoral horns, of which sidewalls have grooves its design is performed by optimization based on the mode-matching method. As a design example, we present a horn with −10 dB beam widths of 33° × 100° at 10 GHz. Effectiveness of the designed horn is verified numerically and experimentally.
This paper proposes an inter-symbol interference (ISI) suppression scheme employing periodic signals for network MIMO-OFDM systems. Network MIMO-OFDM suffers from the ISI due to long time difference of arrival (TDOA) among the users especially in large cells. In the proposed scheme, the periodic signals generated by only the even-numbered sub-carriers is adopted for suppressing the ISI and the appropriate...
This paper proposes a collision detection scheme in asynchronous multiuser-multiple input multiple-output (MU-MIMO) transmission and self-interference cancellation. We assume that asynchronous MU-MIMO which realizes the efficient transmission and other antennas can receive preamble signals while the transmission is employed with antennas which are used in asynchronous MU-MIMO. The self-interference...
This paper investigates the performance of wireless communications using orbital angular momentum multiplexing in terms of modulation/demodulation, multiplexing/demultiplexing, and power control. This work enabled us to clarify the effect of mode-dependent power attenuation and provides insight regarding the potential and limitations of OAM-based wireless communications.
MIMO-OFDM is the generally accepted standard in all WLAN systems. However, this method increases training signals required to estimate the propagation matrix of multi-antenna system. In this study, we investigate methods of shortening VHT-LTF training signal in WLAN systems. Simulation results have shown that 1/2 and 3/4 reduction in VHT-LTF training signal is possible while maintaining a considerable...
Packet relay-assisted scheme using sectorized receiving at relay station has been proved as an effective solution to mitigate hidden terminal problem, and then improve performance of ITS V2V communication. In addition, it is also shown that performance of the relay-assisted scheme relies on separation of the sector antenna unit which is basically expressed as front-to-back (F/B) and front-to-side...
In this paper, a non-Foster circuit for achieving a negative small capacitance based on Linvill floating-type Negative Impedance Convertor (NIC) is realized. The effect of the parasitic elements and the transmission lines on the circuit performance is discussed. The experimental results show that the circuit presents a negative capacitor of 0.87pF in the UHF band. The circuit linearity test reveals...
A metal-frame inverted-F antenna for the metal-casing smartphone is presented. The antenna is formed by two inverted-F Antenna (IFA) structures to cover 824–960 MHz (low band), 1710–2690 MHz (middle band), and 3400–3600 MHz (high band). The antenna for the metal-casing smartphone has a narrow metal clearance of 2 mm. The feeding and shorting strips with matching networks for the two IFAs are disposed...
This paper investigates the effectiveness of the edge folded frequency selective reflector (FSR) structure in reducing mutual influence between low and high band radiation patterns of a dual band reflector backed dipole antenna (RBDA), which employs FSR in the high band RBDA. As the results of the moment method analysis related to the half-power-beamwidth (HPBW) and the front-to-back ratio (FB) characteristics...
A slim vertically polarized omni-directional feed circuit integrated loop slot antenna for mobile base station is proposed in this paper. Picocell antenna requires a compact and slim structure, because its construction space is limited in urban areas. The proposed antenna consists of loop slots and patches to improve omni-directional pattern and bandwidth. In order to enhance the directivity gain,...
The one-body 2-D Beam-switching Butler Matrix and the 2-D Beam-switching Rotman Lens are compared. Those are designed to have sixteen 2-D arranged beams. Comparing the proposed Butler matrix with the Rotman lens, it has the low transmission loss, the high uniformity of distributed beams, and the small size. However when the number of 2-D arranged beams is increased, the size of the Butler matrix is...
Near-field far-field transformation (NFFFT) is one of the solution methods for reducing the long-range requirement of RCS measurement. We proposed a NFFFT technique that utilizes the two-dimensional (2-D) plane-wave expansion. Comparing to the other techniques, this has advantage of near-field (NF) measurement flexibility. However, the applicability to variously shaped targets has not necessarily...
This paper presents a wideband and high efficiency corporate-fed horn array antenna in the E-band. A horn antenna is used as the unit cell of the array. The radiation pattern and grating lobe levels of the unit cell are improved by splitting the horn's aperture with a septum in the E-plane. A ridge gap waveguide corporate distribution network feeds the horns with the same amplitude and phase via coupling...
In this paper, a probe-positioning error estimation of phase retrieval method in planar near-field measurements in millimeter frequency band is presented. Not only is the accuracy of the estimation but also the tolerance of probe-positioning error necessary in high frequency measurements because of its short wavelength. Using phase retrieval method, the accuracy of the estimation is shown in simulation...
In this paper, we demonstrate an E-band plate-laminated 16 × 16-element slotted waveguide monopulse array antenna with corporate-feed using the diffusion bonding technology. The proposed antenna architecture combines radiating elements, a corporate-feed circuit and a comparator, which are vertically interconnected to achieve a compact size and a reduced loss. The design, characterization, and experimental...
We presents characteristics of a free access transmission line consisting of a paper substrate and foam instead of dielectric substrate for easy installation in body area network applications. In this paper, we simulated the coupling characteristics between two dipole antennas above the proposed transmission line to show its basic performance. The average of coupling characteristics above the transmission...
SAR Tomography processing by using multiple SAR images can create a 3-D image including the height distribution of scatterers. The height estimation can be realized assuming that the multi-baseline observation data as an array data in the DOA (direction of arrival) estimation methods. Orbit error in observation might cause DOA/height errors in imaging results; therefore, calibration of orbits or equivalent...
In western Japan, the terrestrial digital TV waves have possibilities of influences by co-channel overreach interferences from not only Japan but also Korea. We have been observing the interferences based on our original measurement method using FM waves for identifying the interference of TV wave. In this study, we evaluated seasonal characteristics of overreach interferences from Japan and Korea...
Imaging of the human body using ultrawideband (UWB) radar for security applications has numerous advantages over other approaches. Recently, low-cost radar systems have been intensively studied for this purpose, employing Doppler interferometry technology to image a single human target. The technique, however, has limitations when there is more than one target person in the scene. To resolve this...
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