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In this paper, three Vivaldi antenna are introduced to compare their performance. As base for our study an ordinary Vivaldi antenna is designed. Then defected ground structures (DGS) are employed to extend the low-end bandwidth limitation and improve the radiation characteristics at lower frequencies. A prototypes with 4 pairs of DGS placed in the antennas is fabricated and experimentally compared...
In this paper, a wide-band circularly polarized (CP) crossed dipole antenna is proposed. The CP crossed dipole antenna is backed by a cavity reflector to achieve wide-band CP radiation with enhanced gain and uni-directional pattern accompanied by high front to back lobe ratio. A comprehensive study on the effect of the vertical walls of the cavity reflector on the CP radiation performance has been...
This paper introduces a new antenna model designed to be applied to V2V communications. This antenna can be integrated easily into the automobiles infrastructure and was designed for VANET networks [1] based on LTE technology and IEEE 802.11p standard [2]. The design of this model is based on operating frequencies of these two technologies. In the design process, it was prioritized that each operating...
In this paper, we present a measurement campaign of indoor massive MIMO channels by using a wideband channel sounder and a rectangular large-scale array with 256 elements. The measurements are conducted at 11 GHz, with a bandwidth of 200 MHz, and the light-of-sight (LOS) scenario is considered. Some basic channel parameters, including shadow fading, delay spread and coherence bandwidth, are extracted...
This paper presents an analysis of four impedance matching techniques to apply in tapered microstrip patch antenna fed by microstrip-line. The techniques used are inset-feed, quarter-wave transformer, displaced-line, and hybrid-line, which is a combination of the other three techniques. The antennas were designed to an operation frequency of 5 GHz. Antenna analysis and measurement were done using...
Although non-Foster broadband metamaterials have been demonstrated both theoretically and experimentally, this concept is still challenging due to inherent stability problems. On the other hand, there is a recent idea of using the unstable non-Foster elements in a broadband tunable radiating system. Here, we propose a concept of a self-oscillating tunable Fabry-Pérot antenna, and verify it by measurements...
A new Ultra-Wideband Antenna with notched band performance for WiMAX is proposed. The antenna has an extended impedance bandwidth from 3 up to 12GHz (120%). The band-notched can be controlled by adjusting the length of the rectangle slot. In order to obtain Omni-directional wide bandwidth antenna with uniform radiation pattern, rounded corners ground plane with two L-shaped slots are utilized to the...
This paper aims to present the influence of a metasurface, a special type of metamaterials, in the performance of a microstrip antenna. We design and manufacture a microstrip antenna with and without the use of a metasurface. Simulations were done with ANSYS software and measurements were realized with a E5071C ENA Network Analyzer. A comparative analysis, showing how the metasurface changes the performance...
This paper presents the analysis of microstrip monopoles for applications in ultra wideband systems (UWB). Antenna structures using circular and semi annular ring patches are considered. The antennas are printed on a FR4 dielectric substrate and present truncated ground planes with a small cut beneath the microstrip line feeder to improve the antenna impedance matching. Results for return loss, resonant...
High-accuracy indoor radio positioning can be achieved by using high signal bandwidths to increase the time resolution. Multiple fixed anchor nodes are needed to compute the position or alternatively, reflected multipath components can be exploited with a single anchor. In this work, we propose a method that explores the time and angular domains with a single anchor. This is enabled by switching between...
Nowadays, many emerging technologies, such as Augmented and Virtual reality, require extremely high-rate data transmissions. This imposes an increasing demand on the network throughput, which currently surpasses the capabilities of commercially available wireless communication systems. To address this constraint, some companies are considering the implementation of high-throughput wired technologies,...
The demand on higher data rate in modern communication systems leads to the use of multiband applications. A multiband double layered microstrip antenna is designed for this purpose. The patches are shaped through variation of the widths and lengths of tri-slots to achieve reflection minima at 3.1 GHz, 5.8 GHz, 7.4 GHz and 9.8 GHz, which cover many applications such as WiMAX, Wi-Fi or other wireless...
A compact strip-loaded slot antenna fed by microstrip line with double feeding strip and double blended stub is present. With the use of proposed feeding, the rectangular slot antenna achieves a very wide impedance bandwidth of 167%, which can operate in frequencies lower than 960 MHz for ground penetrating radar (GPR) applications. In addition, the two curved strips are used for changing the behavior...
The cellular data traffic has been dramatically increased, a typical approach is considering the operation of the Long Term Evolution (LTE) system in the unlicensed spectrum. Although there are a large number of theoretical researches on LTE-U, field trial results are still lacking. In this paper, we build a real time field trial in 5.8GHz unlicensed bands. The typical indoor scenario is deployed...
Ray tracing is a useful tool to model the spatial and temporal propagation parameters of electromagnetic radiation. The model can normally improve by the channel sounding. However, discrepancies may arise between the channel sounding and ray-tracing model due to it needs a wide bandwidth to differentiate the incoming signals, also the antenna radiation pattern may change dramatically over this wide...
Millimeter wave (mmWave) communication has been a key technology for the fifth generation (5G) wireless communications. There have been various mmWave channel measurements. However, many measurements in the literature are conducted with different configurations, which may have large impacts on the propagation channel characteristics, and make the comparison of propagation channel characteristics for...
Results concerning joint Spectrum Availability (SA) monitoring in the 5–10 MHz range of the High Frequency (HF) band (3–30 MHz), for a 24-hour period, in two locations situated in the central and western part of Romania are reported. Measurements have been realized simultaneously in the two locations, with similar USRP SDR-based equipment, for 24 hours on February 27, 2017. Results indicate that SO...
A design concept for a wearable device is proposed. The coplanar waveguide is ground-connected to short the bottom ground. The proposed antenna was fabricated on 0.4-mm-thick 20 mm × 15 mm FR4 substrate, and exhibited a bandwidth of 300 MHz (2.33–2.63 GHz). The antenna is sufficient for covering the 2.4-GHz Bluetooth/WiFi band.
An ultra-wideband Vivaldi antenna with dual-polarization capability is presented. A two-section quarter-wave balun feedline is developed to feed the tapered slot antenna, which improves the impedance matching performance especially in the low frequency regions. The dual-polarization is realized by orthogonally combining two identical Vivaldi antennas without a galvanic contact. Measured results have...
This paper introduces a 16 element, 1GHz IF input, digital beamformer (DBF) that generates 4 independent simultaneous beams, with 100MHz bandwidth. Although DBF has several advantages over analog beamforming, including higher accuracy and multiple beam generation, application of on-chip DBF has been limited due to high power consumption and large die area. The proposed architecture addresses these...
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