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This paper presents a concept for a satellite-based solution for assured communications for mobile public safety groups, law enforcement vehicles and other first responders. System connectivity is assured under normal operating conditions through a combination of wireless base stations and, in areas with minimal or no existing terrestrial communications infrastructure or following a disaster, satellite...
A near-field direct antenna modulation (NFDAM) transmitter at 2.4GHz is demonstrated on a microstrip setting. The transmitter is capable of transmitting information in a direction-dependent fashion by sending the correct signal constellation only in the desired direction while leaving the signal constellation points scrambled in undesired directions. This direction-dependent constellation scrambling...
In this paper, the time modulation technique is extended to circular antenna arrays. The TMSA is adopted to synthesize a flat-topped pattern and scanning sum beams with lower amplitude excitation dynamic-range ratios or even uniform amplitude excitations, as compared to those of the CSA. The studies show that TMCA is a promising approach in synthesizing flat-topped pattern or scanning sum patterns...
Reconfigurable antennas have received much attention in the past years playing an important role in the design of smart and adaptive systems. They have been benefited from recent improvements in the performance of the existing switching technologies. In particular, integrating active devices such as MEMS switches or solid state switches in antennas and microwave circuits have been proved to be useful...
In this paper, a novel technique for electronic beam scanning in TM linear array is proposed. This technique is realized at the first positive sideband. By controlling the duration of "on" times of each element the desired pattern can be synthesized and by adjusting the switch-on time instant of each element, the electronic beam scanning can be realized. Differential evolution strategy (DES)...
The results obtained using WIPL-D for simulation of a seven element helicopter-mounted switched-beam antenna have been discussed. We have discussed the magnitude of the distortions caused in the antenna amplitude pattern for different rotor blade positions. We compared the results from these simulations to patterns when the main rotor and rotor hub are removed from the helicopter. This allows us to...
A small frequency reconfigurable antenna consisting of a PIFA and a monopole have been presented for mobile phone applications. The PIFA, with the use of a switch, can cover LTE, GPS, GSM900, and DCS 1800, and the monopole can cover PCS 1900. The switch will be included in the future work.
In this paper, the potentialities of time-modulation are further investigated in the framework of compromise array synthesis as an alternative solution to standard compromise methods. More in detail, starting from a set of static excitations aimed at synthesizing a user-defined sum pattern at the carrier frequency, a compromise difference beam is generated through a suitable sub-arraying pattern matching...
In this paper, the linear polarization switchable patch array antenna is proposed and the characteristics of the proposed antenna are investigated experimentally. The proposed antenna consists of a fed patch element and four parasitic patch elements. The fed element has a cross slot at the center of the patch and four switching diodes are embedded in a star form across the slot. The parasitic elements...
The idea of this paper is to use simple symmetrical structures offering the possibility of pattern diversity or beam switching by using various feed points. Therefore, this paper focuses on a Sierpinski shaped patch antenna, offering the possibility to adjust the main beam of the antenna in three directions by using three different feed points in one structure. In contrast to the investigations in...
Multiple-input multiple-output (MIMO) technology is a technique which can increase capacity by exploiting multiple antennas in transceivers without the need for extra spectrum or transmit power. This technique is expected to be employed in handheld devices as high bit rate intensive applications become more popular, such as internet access, high definition signal transmission or on-line gaming. However,...
An 8-10 GHz imaging radar system has been presented, demonstrating excellent experimental results when implementing STW applications on drywall material. As an extension, a reconfigurable ultra-wide band STW radar system is proposed to be employed in conjunction with various types of building materials. The reconfigurable system can be reconfigured using four SPDT switches to operate at either a 1-3...
A novel compact planar inverted-F antenna (PIFA) with reconfigurable feedings for GSM/PCS/DCS applications is proposed in this paper. The U-shaped PIFA with only one branch is folded into 3 planes is designed to reduce the dimensions. The antenna occupies a relatively small volume of 50*7*7 mm3. Two feeds can be switched to achieve two different matching states, and GSM/PCS/DCS bands can be covered...
Rapid developments in computer techniques and high performance networks have led to the widespread use of the parallel FDTD method for solving large EM problems. It is well known that the FDTD method is an embarrassingly parallel algorithm, which can make an efficient use of a computer cluster to reduce the computation time almost linearly as the number of nodes is increased, provided that the code...
This paper aims to design a switching scanning beam antenna operating at 2.45 GHz based on the principles of cylindrical reflector antennas integrated with the feature of FSS in the second part of its spectral response (Habib et al., 2008). An active cylindrical frequency selective surface (ACFSS) is proposed to benefit the interesting feature of FSS textures as an EM shutter to control the electromagnetic...
A circular loop antenna with feed points on the loop is proposed. This antenna is envisaged to be useful for some beam steering applications. An example of this antenna with 8 feed points is analyzed. The eight feed points are placed symmetrically on the loop, which when excited one at a time steer the beam in eight different directions at steps of 45deg. Apart from the direction of the beam, the...
The improvement of mobile reception performance for satellite digital audio radio services is investigated, combining a novel scan/phase antenna diversity system with a new diversity antenna set which can be mounted easily underneath one radome on the roof of a car. In combination with the scan/phase antenna diversity system the new diversity antenna set yields an improvement in reception quality...
This paper presents a design concept to aid in the detection and tracking of objects in a cluttered environment. The goal is to uniquely identify large, relatively cylindrical metallic objects in a warehouse setting. In addition to the challenge of determining the object's precise location, it is also desirable to uniquely identify each cylinder. The application is similar to RFID but differs in that...
This paper presents a new approach for the design of a multi-band reconfigurable antenna. Different rotating slot configurations of the antenna are considered during the design in order to achieve a reconfigurable antenna without the use of active switches. The designed structures are based on cellular automata rules. Prototype antennas were fabricated and tested to prove the proposed method.
Direction of arrival (DOA) estimation is a very important technology for smart antennas, which have been widely used in many applications such as radar, communication and sonar etc. Various techniques for DOA estimation have been proposed. The commonly used techniques for DOA estimation are subspace based methods, such as multiple signal classification (MUSIC) and its variations. However, these methods...
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