In this paper, a multiple input multiple output antenna which operates at 5.8 GHz for wireless local area network applications is proposed. The proposed antenna is composed of two sets of four elements antenna array (2 × 2) on the top and a novel metamaterial structure on the ground plane. Here, the ground plane, which includes a lattice of 2 × 5 unit cells of metamaterial structure, is utilized in order to improve parameters of the antenna. Thanks to the proposed metamaterial structure, not only gain and bandwidth of antenna are enhanced, but also mutual coupling is reduced. The final design, with an overall size of 137 × 77 × 3.048 mm3, resulted in a |S11| <−10 dB bandwidth of 1.78 GHz and a peak gain of 9.2 dBi. In addition, the isolation is higher than 18 dB although the close separation from edge to edge of the two antennas is only 2 mm and radiation efficiency of 73% at the operating frequency band. All is simulated based on CST Studio software and the simulated S-parameter results of the antenna are in good agreement with measurement results.

The measurement results of detection-of-arrival (DoA) of coherent signals using five-port reflectometers and quasi Yagi antennas are presented. The receiver operating at 2.4 GHz consists of eight five-port reflectometers and a uniform linear array (ULA) of eight 2.4 GHz quasi-Yagi antennas. The DoA is estimated by measuring the phase difference of signals pitched by the antenna array and by using the MUSIC algorithm associated with Spatial Smoothing Pre-processing (SSP). The phase difference is determined using the five-port technique. The measurement results show that the DoA of coherent signals are well estimated with a maximum error of 2 . In addition, we also show that it is capable of estimating the time delay and direction of arrival simultaneously using the five-port technique.

This paper presents the measurement results of by a digital signal processor (DSP). Digital receivers will be Direction-Of-Arrival (DOA) in azimuth plan using a uniform applied in various systems such as in wireless, in cellular, in linear array (ULA) and an all digital receiver array in which the radar, in localization systems, in intelligent transport system Radio Frequency signal is directly digitized by the Analog-toand so on. In these applications, localisation information is Digital Converters (ADC). Our further goal is the real-time measurement of DOA devoted to an inter-vehicle in the highly demanded. The localisation may be based on TOA intelligent transport systems. The DOA of RF signal is estimated (Time Of Arrival), on TDOA (Time Difference Of Arrival) or using the high resolution method named MUSIC (Multiple Signal on DOA (Direction Of Arrival). A practical solution for Classification). The measurement setup composed of a 4 quasiwireless communications in the future as multiple antennaYagi element ULA and of 4 parallel all digital receivers based on systems or adaptive antenna systems holds considerable a digital oscilloscope is realized. The simulation results using promise in the future. The development of a positioning ADS (Advanced Design System) and the measurement results system by means of DOA using a digital receiver array will be show that the DOA is accurately determined with this all digital important. In section II, the system architecture and signal receiver solution.processing are presented. The measurement system is Index Terms: Digital receiver, Localisation system, Direction described in section III followed by the simulation and of arrival, MUSIC. measurement results in section IV. A brief conclusion is given in section V.

Two new designs of the L-shaped Planar Inverted–F Antenna (PIFA) antennas with single and dual polarization operating at the frequency band for IEEE 802.11b/g standard with satisfactory radiation characteristics are presented. We further propose a genetic algorithm (GA) embedded in CST Microwave Studio for optimizing these antenna parameters. The agreement of simulation and measurement results shows the performance of our joint model. Also, they show that our dual-polarization antenna is suitable for indoor Multiple Input Multiple Output (MIMO) wireless environment applications.

The main advantage of an optoelectronic oscillator (OEO) is the ability to synthesize directly very high spectral purity frequency in microwave domain. Beside applications in radar, telecommunication and satellite systems, OEO can also be used in sensor applications such as refractive index or distance measurements. However, the long-term stability of the OEO is easily affected by ambient environment variations. The optical fiber loop effective refractive index varies corresponding to its surrounding temperature changes. Consequently, it makes the optical transmission path inside the fiber loop differ from the initial state, leading to oscillation frequency changes. To stabilize the single loop OEO, it is essential to keep its high Q elements in a well-controlled thermal box as much as possible. Unfortunately, in the real implementation condition, this requirement is difficult to be satisfied. In this paper, we present a new technique to estimate the oscillation frequency variation under the room temperature by using a vector network analyzer (VNA). Experimental results show a good correlation between OEO oscillation frequency drift and the phase measured by the VNA. This technique can be implemented to apply corrections when using the OEO as a distance variation or a refractive index measurement tool. We also tracked the temperature of the fiber loop at the same time with the VNAbased experiment to compare two correlations of temperature and phase with OEO oscillation frequency.