This paper proposes a multi-stacked mushroom structure to suppress the mutual coupling between monopole antennas, whose height is taller than that of a conventional mushroom structure. Based on moment method analysis results, it is clarified that the multi-stacked mushroom structure can suppress the mutual coupling more than a conventional 2D arranged structure. Furthermore, the validity of the results is clarified by experiments.
This study proposes a heterodyne Costas optical phase-locked loop (HC-OPLL) circuit for frequency nondegenerate optical parametric phase-sensitive amplification (ND-PSA) of phase-conjugated twin waves (PCTWs), and experimentally demonstrates stabilization of phase-sensitive gain in the ND-PSA by the HC-OPLL for the first time. First, theoretical derivation shows the proposed HC-OPLL circuit can correct phase error between PCTWs and a pump. Then, stabilization of phase-sensitive gain in ND-PSA of PCTWs with 42.3-GHz frequency spacing is experimentally demonstrated using the HC-OPLL circuit. The proof-of-principle experiment shows that gain fluctuations are reduced successfully through the use of HC-OPLL circuit.
Recently, the S-parameter method, which is the measurement method of the input impedance of the balanced antenna, has been proposed. In this paper, to show the possibility of the S-parameter method using jig fabricated microstrip line, the input impedance of a bow-tie antenna is examined. As a result, it is observed that the results of the S-parameter method are shown to agree with the other results at frequencies less than 3 GHz. In addition, it is thought that the main cause of the measurement error of the S-parameter method using the MSL type jig is due to the electromagnetic coupling between the antenna element and MSL.
To improve the performance of sparse representation based space-time adaptive processing methods, the multiple measurement vectors joint sparse representation (MMV-JSR) model of MIMO radar received signal of testing range cell is established. Then, MMV FOCal Underdetermined System Solver is applied to estimate clutter-target space-time spectrum. At last, clutter plus noise covariance matrix and the weight vector of STAP processor are calculated based on the clutter distribution obtained by using the rough priori knowledge of target. Numerical results demonstrate that our method has great performance of clutter suppression and target detection.
This paper presents an efficient node pair selection scheme in multiuser MIMO communication network with plural transmitters and receivers based on concept of stable marriage problem. The first step is determination of the order of preference in both of transmitter and receiver sides, and for this aim, five types of metrics derived from channel matrices are considered. The second step is node pair selection using Gale-Shapley algorithm based on the preference order. Computer simulations show that the node pairs obtained by the proposed method can achieve higher performance with quite low additional computations.
The ability of a printed single-layer monopole antenna, which is composed of diamond-fed slotted top-loading, asymmetric co-planar waveguide (ACPW) and stepped-feeding structure, to operate at three wide frequency bands (698∼960 MHz, 1710∼2690 MHz and 3400∼3800 MHz) to cover WLAN and LTE operation has been demonstrated in this article. A prototype of the proposed antenna with 106 mm in length, 0.8 mm in thickness and 15 mm in width is fabricated and experimentally investigated. The experimental results indicate that the VSWR 2.5:1 bandwidths achieved were 71.43%, 48.16% and 13.89% at 700 MHz, 2450 MHz and 3600 MHz, respectively. There is good agreement between the simulated and measured results.
In this letter, we propose a simple method for analyzing the statistical properties of signal propagation in a line-of-sight (LOS) multipath fading environment, such as in inter-vehicle communications which use a Multiple-Input-Multiple-Output (MIMO), Multiple-Input-Single-Output (MISO) or Single-Input-Multiple-Output (SIMO) system. Specifically, in our method, ray tracing is only used to calculate the spatial correlation characteristics between a pair of transmitting and receiving antenna points that are used as a reference in an outdoor model, and these characteristics are then applied to the Kronecker model to estimate the statistical properties of the surrounding areas. Compared with the results calculated by ray tracing alone or the simplified method that we proposed previously, it is found that the channel characteristics can be estimated to a high degree of accuracy with a very short computation time using the proposed method.
This paper presents a weighted-polarization antenna applied to BAN (Body Area Network) on-body communication systems. A primal objective is to achieve the radio link enhancement in both downlink and uplink on-body channels. The proposed antenna obtains an optimum signal level using a weight function considering the BP-XPR (Body Proximity Cross-Polarization Power Ratio) and antenna tilt angle. The results show that the proposed antenna achieved more than a 3-dB improvement of received signal compared with the other types of antennas, such as vertical dipole, horizontal dipole and equal weight combined antennas, regardless of the arm-swing motion and antenna placement, which verifies the effectiveness of the proposed method to enhance BAN on-body radio links.