An antenna is a device that is used to transfer guided electromagnetic waves (signals) to radiating waves in an unbounded medium, usually free space, and vice versa (i.e., in either the transmitting or receiving mode of operation). Antennas are frequency-dependent devices. Each antenna is designed for a certain frequency band. Beyond the operating band, the antenna rejects the signal. Therefore...

Directional antennas shape transmission patterns to provide greater coverage distance and reduced coverage angle. Use of adaptive directional antenna arrays can minimize interference while also being more energy efficient. When used in an ad-hoc network, this reduces interference among transmitting nodes and thereby increases throughput. Such “smart antennas” use digital beamforming based on si...

Beam-space MIMO has recently been proposed as a promising solution to enable transmitting multiple data streams using a single RF chain and a single pattern-reconfigurable antenna. Since in a beam-space MIMO system radiation pattern of the transmit antenna is exploited as extra dimension for encoding information, near-field interaction of the transmit antenna with its surrounding objects affect...

A linear inversion scheme for microwave imaging of buried objects is presented in which arbitrary antennas are accounted for through their plane-wave transmitting and receiving spectra. INTRODUCTION Ground penetrating radar (GPR) is an efficient tool for microwave imaging of buried objects. Within the concept of diffraction tomography, as proposed by Devaney [1], several linear inversion scheme...

This paper proposes orthogonal Discrete Frequency Coding Space Time Waveforms (DFCSTW) for Multiple Input and Multiple Output (MIMO) radar detection in compound Gaussian clutter. The proposed orthogonal waveforms are designed considering the position and angle of the transmitting antenna when viewed from origin. These orthogonally optimized show good resolution in spikier clutter with Generaliz...

This work presents an application of convex optimization and algebraic geometry in devising secure, powerefficient, beam-steerable, and on-chip transmission systems for wireless networks. First, we introduce a passively controllable smart (PCS) antenna system that can be programmed to generate different radiation patterns in far field by adjusting its variable passive controller at every signal...

Frequency-swept input-impedance measurements to determine Q factors and field strengths for an electrically small tuned transmitting loop antenna in its operating environment have recently been made. These observational results are compared with numerical modeling by the computational electromagnetic code NEC-4D, since the validity of this code to simulate the performance of electrically small ...

A dielectric array transmitting structure, formed into a partial circle, demonstrated the propagation of electromagnetic fields that decayed with distance by 1/R rather than 1/R. The array had an electromagnetic field wavefront with an angular rate which will present signal detection and identification problems to conventional antenna-receiver-signal processing systems. A properly structured cy...

This paper proposes orthogonal Discrete Frequency Coding Space Time Waveforms (DFCSTW) for Multiple Input and Multiple Output (MIMO) radar detection in compound Gaussian clutter. The proposed orthogonal waveforms are designed considering the position and angle of the transmitting antenna when viewed from origin. These orthogonally optimized show good resolution in spikier clutter with Generaliz...

This Paper aims at evaluating the performance of 3GPP Long Term Evolution (LTE) Downlink system under Urban Microcell Scenario for different MIMO transmission schemes. The performance parameters such as, Bit Error Rate (BER) and the Data Throughput are reported in terms of Signal to Noise Ratio (SNR) for different types of transmitting antenna and Modulation scheme. Transmit diversity scheme kn...