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For the non-uniform circular antenna array, the algorithm based on multiple signal classification (MUSIC) is a high-resolution estimation algorithm on direction-of-arrival (DOA). This paper analyzes that the direction finding precision of multiple signal classification (MUSIC) algorithm is under the different background signal-to-noise ratio (SNR), multi-path or mirror reflection, and different number...
A wideband semi-periodic circular high impedance surface for loop antenna applications is designed. The surface is illuminated with a plane wavw whose electric field is of phi component. A loop antenna is placed above the surface afterwards to find the operational bandwidth of the structure.
We propose the development of a printed logoperiodic antenna, by combining the operating principles of the conventional logoperiodic with the construction technique of printed microstrip. Hence we obtain a compact design and small size antenna whose frequency response is within the expected bandwidth. This antenna will be used in conjunction with a detector device for true RMS values of RF signals...
Thales Alenia Space (TAS) has started the “COMPACT-SAR” internal programme to develop a SAR satellite characterized by low cost and reduced mass while providing, at the same time, high image quality in terms of resolution, swath size, and radiometric performance. COMPACT-SAR is a satellite embarking an X-band SAR based on a new technology for the Antenna Subsystem. It consists of an innovative deployable...
This paper presents a circularly polarized antenna on thin and flexible Denim substrate for Industrial, Scientific and Medical (ISM) band and Wireless Body Area Network (WBAN) applications at 2.45 GHz. Copper tape is used as the conductive material on 1 mm thick Denim substrate. Circular polarization is achieved by introducing rectangular slot along diagonal axes at the center of the circular patch...
In this paper, a low-cost dual-band printed antenna that employs Sierpinski fractal geometry is proposed for possible integration to IEEE 802.11n WLAN standards access points. The designed antenna covers two wireless spectrum bandwidth, they are the ISM 2.4 GHz and the U-NII 5 GHZ. The antenna geometry is confined within a compact size of 75 × 75 × 1.8 mm3. The antenna is mounted on partial ground...
An effective technique to compensate known positioning errors in a nonredundant near field - far field (NF-FF) transformation with plane-polar scan, using an oblate ellipsoid to model the antenna under test, has been experimentally validated at the UNISA Antenna Characterization Lab. It employs the singular value decomposition method to retrieve the probe voltage samples at the points fixed by the...
This paper investigates how typical frequency domain concepts such as circular polarization and axial ratio can be given a useful meaning in the time domain. The relationship between the linear polarizations of a circularly polarized time dependent signal is shown to be the Hilbert transform, and the instantaneous axial ratio can be computed from envelope functions, obtained from corresponding analytical...
The safety of on-duty firefighters in indoor environments could be increased by ensuring reliable, high-data rate communication in potentially life-threatening situations. This increases their situational awareness, strengthens their decision making and decreases response time by ensuring efficient indoor communication of sensor data, biometric data, pictures or videos. Therefore, a real-life rescue...
Main objective of this contribution is to introduce a novel collision avoidance protocol for the chipless Radio Frequency Identification (RFID) systems. The chipless RFID tags are dummy, memoryless, with limited number of bits, very low backscattered power and short reading range. Therefore, the existing RFID standards and protocols designed for the chipped RFID systems are not applicable for the...
The evolution of modern mobile terminals has been driven by the user interface and broadband connectivity. While rapidly rising peak data rates have been achieved, real world baseline performance has fallen substantially over the years. The key factor driving this degradation has been reduced antenna volume driven by the race for thinner and display-dominated platforms. To maintain acceptable efficiency,...
In this paper, the conception of a multiband antenna dedicated to the UMTS/PCS/WLAN/BLUETOOTH/LTE standards, is presented. A design methodology in order to obtain an efficient antenna is also proposed in this work. The antenna is composed of five elements: a main radiating element and four parasitic elements. The parasitic element technique is the single method used here to enhance the antenna's bandwidth...
In this paper, a new strategy for the design of active matched antennas with non-Foster elements is presented. The aim of this work is to complement the design process through considerations of sensitivity to circuitry location, Non-Foster elements stability, radiation efficiency and current distributions in order to enhance the antenna performance. A design example using an electrically small antenna...
This paper proposes a new architecture for mobile phone front-ends that dramatically reduces the complexity of multi-band smart phones. Traditional smart phone front-ends consist of many parallel transmit (Tx) and receive (Rx) chains each dedicated to a single band. The proposed architecture simplifies this by making few fully frequency tunable Tx and Rx chains that each cover multiple bands.
A tunable reflectarray phase-shifting cell, designed for a resonance frequency of 5.5 GHz, is presented. The cell is based on a triple-slot topology and loaded by a ferroelectric thin film capacitor with 60% tunability under 400 kV/cm bias electric field. The use of three slots allows reducing the losses and increasing the bandwidth of the cell. The cell provides 270 degrees of phase range with a...
X-band reconfigurable reflectarray (RRA) cells having two, three, and four discrete reflection phase states are presented in this paper. The cell topology enables independent dynamic reflection phase control of each linear component of a dual-polarized wave. The reflection phase step deviation is smaller than the quantization error in 12.5% bandwidth for the two and three states designs and in 6.5%...
The adoption of metamaterials in the development of terahertz (THz) antennas has led to tremendous progresses in the THz field. In this paper, a reconfigurable THz patch antenna based on graphene is presented, whose resonance frequency can be changed depending on the applied voltage. By using an array of split ring resonators (SRR) also made of graphene, both bandwidth and radiation properties are...
The accuracy of the reverberation chamber has been investigated when mode stirring is performed with a plate placed on a rotatable platform, i.e., plate-on-platform stirring. The accuracy and scanning volume of the platform plate are then compared to the original mode stirring plates that are moving alongside two walls. The results are also compared to physical theoretical models. The mode stirring...
The lowest frequency in the bandwidth of a spiral antennas is limited by the size of the antenna. Horizontal connections between spiral arms of opposite polarization have been devised in linear arrays in order to reduce the lowest frequency in the bandwidth. This paper shows the reflection coefficient (|S11|) and axial ratio (AR) are greatly enhanced at the low end of the frequency bandwidth by connecting...
In this paper, the on-body performance of three quasi-static channels was evaluated, when the human body undergoes certain typical movements. The main contribution of this work is the analysis of the impact of body movements on the performance of the on-body system in a mine environment. The quasi-static channels parameters were determined and compared to those of a corresponding static channel.
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