In a majority of currently deployed wireless communication systems, the objective is to sell a product.We describe standard cellular antennas, smart antennas using fixed beams, and adaptive. Wireless communication systems are limited in performance. SIGNALS AND SYSTEMS.The adoption of smart adaptive antenna techniques in future wireless systems is. The main impediments to high-performance wirel...

In this paper, we apply two different types of space-time block codes (STBC) in the downlink of a broadband mobile radio air interface based on MCCDMA, which is a promising candidate for a 4 generation mobile radio system. The first type are ”STBCs from orthogonal designs”. For 2 TX-antennas, this is the wellknown ”Alamouti”-scheme. These STBCs are compared to a different type, called cyclic de...

We further describe an implementation of this system that uses an array of 32 antennas to communicate with 32 single-antenna clients simultaneously on the same frequencies between 512-608 and 614-698 MHz. At close range, all 32 links achieve the full PHY data rate, both uplink and downlink, with less than 1% Block Error Rate on each link. The total system rate is 3.8 Gb/s. The system spectral e...

But first concerning controversies there is also a controversy concerning the use or non-use of baluns, and which balun to use. Since many antenna types are balanced, and present day HFTPA’s are unbalanced, and, since the preferred method of feeding antennas is to use coaxial cable, rather than 2-conductor balanced transmission line, a balun should, often must be used in the overall antenna sys...

Ultra wide band systems are used in wide variety of applications due to its resistance to severe multipath and jamming, low complexity and low cost. UWB finds extensive application in mobile handsets. Microstrip antennas are used in ultra wide band applications because of its low profile, high efficiency and economical fabrication features. In this paper, a comparative study of various antennas...

Electronically Switched Directional (ESD) antennas allow software-based control of the direction of maximum antenna gain. ESD antennas are feasible for wireless sensor network. Existing studies with these antennas focus only on controllable directional transmissions. These studies demonstrate reduced contention and increased range of communication with no energy penalty. Unlike existing literat...

Some useful features of microstrip patch antennas are low profile, low weight and easy fabrication. However this type of antenna suffers from having a low gain, caused by propagation surface waves. In this paper, a new near zero refractive index metamaterial (MTM) unit cell is designed and fabricated as a superstrate over a Rectangular Microstrip Patch Antennas (RMPA). In order to obtain a maxi...

In this research work, a multibeam antenna which is a combination of a beamformer network (BFN) and a linear array antenna, has been designed. A Rotman lens has been chosen as beamformer network and Vivaldi antennas have been selected for constructing array antenna. The Substrate Integrated Waveguide (SIW) was used for implementing Rotman lens. After explanation the structure of Substrate integ...

Abstract— This work investigates the improvement of the active reflection coefficient of waveguide-fed phased-array antenna using liquid crystal layers. The anisotropy properties of liquid crystal layer can be employed to eliminate blind scan angle and improve the wide angle impedance matching of the waveguide-fed phased array antennas. The authors have expressed the modal analysis of the waveg...

This paper presents a data focusing method (DFM) to image extended targets using the multiple signal classification (MUSIC) algorithm. The restriction on the number of transmitter-receiver antennas in a microwave imaging system deteriorates profiling an extended target that comprises many point scatterers. Under such situation, the subspace-based linear inverse scattering methods, like the MUSI...