We introduce a wideband and dual polarization antenna for mechanically-driven planar arrays. We previously proposed an antenna element based on open-ended waveguide. This paper designs a distribution network to connect four of these antenna elements by a strip line. The strip line network simplifies the waveguide manifold needed for constructing large scale planar arrays. Even though the wiring is asymmetrical, numerical simulations confirm its almost ideal transmission characteristics. We also fabricate a four-element subarray and demonstrate its performance. Total reflection including the antenna elements, strip lines, and waveguide transformer was −11 dB or less across 30% bandwidth.
In this paper, a distributed algorithm for dynamic frequency reuse scheme in OFDMA downlink cellular networks is proposed. Each cell is divided into two regions, namely, inner and outer regions. The proposed distributed algorithm is based on minimizing the total interference at all users in each region. Unlike other fractional frequency reuse (FFR) schemes, the main advantage of the proposed algorithm is that it adapts to the network channel conditions. Simulation results show that the proposed algorithm provides better performance than that of FFR, in terms of both total system throughput and average user bit-rate.
This paper presents experimental studies on the improvement of RF-DC conversion efficiency of the rectenna using a high Q λ/4-coaxial dielectric resonator and distributed capacitors at 850 MHz. In order to achieve an ultimate efficiency, we have constructed a rectenna using both a coaxial dielectric resonator and a film capacitor. The measured results show that the developed rectenna has an RF-DC conversion efficiency of 76.2% and 44.1% at a low input power of 1 mW and 0.1 mW that achieves the 20%-efficiency improvement compared with the rectenna with an LC resonator.
In this paper, we aim at solving the co-channel interference (CCI) between cells in heterogeneous networks (HetNets), employing an interference-aware channel segregation based dynamic channel assignment (IACS-DCA). To improve the energy efficiency in HetNet, a distributed ON/OFF switching algorithm for BSs is proposed in which each BS selects ON/OFF strategy using game-theory. We combine these two algorithms by using the beacon signal. The beacon signal contains the traffic load information to be used for user equipment (UE) association when BS ON/OFF algorithm is employed and it is used for measuring the instantaneous beacon signal in IACS-DCA. We show by computer simulation that by combining IACS-DCA and distributed ON/OFF switching algorithms for BSs, high transmission quality is achieved.
This paper presents a method to achieve the maximum MIMO channel capacity using a weighted-polarization MIMO antenna. Particular emphasis is placed on the way to adjust the phase shift value between the antenna elements to an optimum value in accordance with the variation of cross polarization power ratio (XPR) and the antenna inclination angle. Both the measurement and analytical results show that using the optimum phase shift value, the MIMO channel capacity is increased in comparison with a conventional fixed-phase shift antenna in various conditions.
In this paper, we propose multi-input multi-output (MIMO) transmission using human bodies. The proposed scheme is experimentally evaluated using test subjects, whose bodies are located at different positions. A high channel capacity was achieved by using MIMO transmission. The channel capacity obtained for 2 × 2 MIMO in body-to-body communication is approximately 1.6 times higher than that obtained when using single-input single-output transmission. The experimental results indicate the success of the proposed method in increasing channel capacity using MIMO. The presented research is relatively unique, and the results would therefore be a valuable contribution to this field of research.
In this letter, we propose the designs of new frequency selective surfaces (FSS) for ultra-wideband (UWB) applications. The proposed switchable FSS is a 3D band-pass FSS constituted with a periodic array of two layers, of crossed metallic tapered dipoles, separated by a single-layer band-stop FSS and related by twin wire transmission lines. With this configuration, two propagating paths are formed. One path through the transmission lines with a corresponding band-pass response and the second path allows the propagation through the interlayer with an associated band-stop response. By inserting an on/off switch, between the crossed tapered dipoles, a switchable UWB band-pass/stop response can be achieved.
In previous works forward wave analysis (FWA) was proposed for the EMC design of printed circuit board (PCB) power supply planes. In particular, FWA focuses on the radiation from PCB edges due to simultaneous switching noise on the power supply planes above 1 GHz and helps selecting the stitching ground via location by fast estimating their effect on the radiation. In the present work FWA is confirmed by experimental results up to 10 GHz based on the assumption that the maximum radiated field is approximately proportional to the mean edge voltage between top and bottom planes of the PCB.
This paper describes a variable-reflection-angle meta-surface that can control a scattering pattern by sliding one layer of a double-layered frequency selective surface. A reflection angle within a range of approximately 2° to 35° is obtained in the proposed structure according to the unit cell analysis of the meta-surface. A scattering pattern is calculated by FDTD analysis, and the peaks are in good agreement with the range.