Query: vivaldi

title: Compact UWB MIMO Vivaldi Antenna With Dual Band Notched Characteristics
abstract: A novel ultra wideband (UWB) multiple input multiple output (MIMO) Vivaldi antenna with dual band notched characteristics is presented and fabricated. The antenna is comprised of an improved ground plane and two microstrip feeding lines with a compact size of $26\times 26$ mm2. The evolutionary process of the antenna is given. By etching the T shaped slot on the ground plane, the port isolation between individual antenna elements can be greatly increased. Meanwhile, by adding two split ring resonator (SRR) of different sizes next to the microstrip feed lines, dual notches can be achieved to filter the interfere of WLAN and X band communication satellites. The notched mechanism is analyzed from the surface current distributions. The experimental results show that the impedance bandwidth of the designed MIMO antenna is from 2.9 to 11.6 GHz, along with two notched bands covering 5.3 5.8 GHz and 7.85 8.55 GHz, and the mutual coupling is less than 16 dB in the whole working bandwidth. The MIMO antenna has good radiation characteristics, stable gain, and very low envelop correlation coefficient (ECC <0.02) which is suitable for UWB MIMO system applications. The idea in this paper also has a certain guiding significance for the study of band notched MIMO Vivaldi antenna.

title: A New Method for Achieving Miniaturization and Gain Enhancement of Vivaldi Antenna Array Based on Anisotropic Metasurface
abstract: A low profile printed planar antipodal Vivaldi antenna (AVA) array with good performance for future fifth generation (5G) millimeter wave (mmWave) communication applications is presented. The proposed structure is an <inline formula> <tex math notation="LaTeX"$8\times1$ /tex math>/inline formula> array with eight elements in E plane, which is fed by a 1 to 8 power divider network. A novel feature called anisotropic metasurface (MS) is located at the aperture, resulting in low cutoff frequency reduced from 24.55 to 24.1 GHz for miniaturization. In addition, the phase distribution located at the aperture of AVA array can be corrected by adding MS. Thus, the gain of AVA array can be improved from 8.5 11.2 to 9.35 12 dB in the frequency band of 5G mmWave communication. Finally, to verify the designed methods, the proposed AVA with MS (AVA MS) array was successfully fabricated and measured, which occupies an area of <inline formula> <tex math notation="LaTeX"$6.11\lambda _{\mathrm {g} \times 2.93\lambda _{\mathrm {g} \times 0.08\lambda _{\mathrm {g} /tex math>/inline formula> The numerical and experimental results coincide well with each other, which certify the new method for achieving miniaturization and gain enhancement of our proposed AVA MS array.

title: A Compact Gain Enhanced Vivaldi Antenna Array With Suppressed Mutual Coupling for 5G mmWave Application
abstract: In this letter, a novel method of reducing mutual coupling is proposed, and it used on a modified compact broadband antipodal Vivaldi antenna (AVA) array for future 5G millimeter wave (mmWave) communication application. The proposed structure consists of eight antenna elements that are fed by a 1 to 8 power divider. In order to reduce the mutual coupling between AVA array elements, multiple notch structures are added on the ground plane. Thus, the isolation between the antenna elements can achieve a maximal additional 37.3 dB enhancement, impedance bandwidth is extended slightly from 24.65 28.5 GHz to 24.55 28.5 GHz, and the gain is improved simultaneously. To verify the designed method, the proposed AVA arrays were fabricated and measured. They show an overall size of 28.823 mm x 60 mm x 0.787 mm. The measured gain of the modified AVA array is 6.96 11.32 dB in the frequency band of future 5G mmWave communication, which is higher than the initial AVA array, whose gain is 5.34 8.5 dB.

title: Compact Antipodal Vivaldi Antennas for Body Area Communication
abstract: In this paper, compact on body antipodal Vivaldi antennas (AVAs) are proposed for body area network (BAN) which work at the lower ultra wide band (UWB) The antennas are modified by employing the tapered slot edge (TSE) to lower the resonance frequency and improve the radiation characteristics. In order to increase the gain of antenna further so that improve the transimission efficiency from in body to on body, two compact on body AVA arrays are designed operating at the lower UWB. The polarization of the two antenna arrays are linear and mutually perpendicular with each other. In addition, each of antenna arrays are composed of four single elements which are fed by optimized 1x4 Wilkinson power divider. The performance of S11 and far field patterns show that the operating band of the antenna arrays covers the lower UWB band, which signifies that the benefits of introducing TSE to lower the resonance frequency is obvious. Furthermore, the influence of the human body on antenna array is discussed and the results satisfies the requirement of in body to on body communication.

title: An Ultrawide Band Antipodal Vivaldi Antenna for Airborne GPR Application
abstract: An ultrawide band (UWB) antipodal Vivaldi antenna is designed for airborne ground penetrating radar (GPR) system. With exponential tapered slots and slot edges, the presented antenna demonstrates a wide operating band from 300 MHz to more than 2 GHz. The fabricated prototype of this antenna with a compact size of 450 mm <inline formula> <tex math notation="LaTeX"\times 600$ /tex math>/inline formula> mm <inline formula> <tex math notation="LaTeX"\times 1.5$ /tex math>/inline formula> mm has been measured in anechoic chamber. Both simulation and experimental results show that good radiation patterns with gain 4.4 11.5 dBi in the endfire direction could be achieved in the whole working band, which indicates that the proposed antenna is suitable for airborne GPR application.

title: Quarter Wave Balun Fed Vivaldi Antenna Pair for V2X Communication Measurement
abstract: A dual polarized Vivaldi antenna pair has been designed for use in a vehicle to anything (V2X) measurement facility. The operating bandwidth is from 560 MHz to 7.7 GHz (173% fractional bandwidth) covering all the existing V2X communication frequencies. The ultrawideband (UWB) property was achieved by integrating quarter wave baluns at the feeding point of two orthogonally crossed Vivaldi antennas. The measured port isolation between the two antennas is better than 28 dB. The cross polarization discrimination of better than 17.2 dB and antenna gain of up to 9.2 dB have also been realized across the whole bandwidth. Three of the designed antennas were mounted on a vehicle testing facility and were used to measure the radiation patterns of a roof top shark antenna under four different V2X scenarios. That is, vehicle to pedestrian, vehicle to vehicle, and vehicle to infrastructure and vehicle to network. The results have also been presented in this communication.

title: High Gain Antipodal Vivaldi Antenna With Pseudoelement and Notched Tapered Slot Operating at (2.5 to 57) GHz
abstract: Novel methods of improving directivity and decreasing sidelobe radiation via the addition of an elliptical pseudoelement and irregularly spaced notches in the tapered slot antenna are presented in this paper. This antenna has been shown to be functional over the C, X, <inline formula> <tex math notation="LaTeX"\text{K}_{\mathrm {u} /tex math>/inline formula> K, <inline formula> <tex math notation="LaTeX"\text{K}_{\mathrm {a} /tex math>/inline formula> and portions of the <inline formula> <tex math notation="LaTeX"$S$ /tex math>/inline formula> and <inline formula> <tex math notation="LaTeX"$V$ /tex math>/inline formula> bands covering (2.5 to 57) GHz (22.8:1 bandwidth, defined where VSWR 3) Minimum and maximum realized gains of 4 and 16 dB were achieved at 2.7 GHz and 29.8 GHz, respectively. The antenna offers directive radiation patterns with a half power beamwidth under 40deg for frequencies above 6 GHz and under 30deg for frequencies above 32 GHz. As compared with other Vivaldi antennas reported in the past, the proposed design offers a larger bandwidth while providing higher peak gain and average gain. Good agreement was observed between simulation and measurements.

title: Vivaldi Antenna With Pattern Diversity for 0.7 to 2.7 GHz Cellular Band Applications
abstract: This letter describes a planar ultrawideband Vivaldi antenna for base station pattern diversity applications. It is designed to cover most of the cellular and LTE bands, a very wide frequency range from 0.7 to 2.7 GHz. It is formed by two adjacent Vivaldi tapered slots with a rotated angle of 29deg between them. The antenna is miniaturized by sharing some common structure and cutting the noncritical board area. It is designed step by step from a single Vivaldi element with a microstrip line feeding to a dual slot pattern diversity radiator with uniform radiation patterns. It is fabricated and tested inside a near field chamber. The radiation performance, including both in phase and 180deg out of phase differential feeding cases, is verified by simulation as well as experiment. The measured results show good agreement with the simulation. It could be useful for base station and other smart array systems.

title: Is there a specific Vivaldi effect on verbal memory functions? Evidence from listening to music in younger and older adults
abstract: Brief exposure to music has been reported to lead to transient improvement of cognitive functions in no music domains. Regarding the possible roles of working memory, processing of acoustic regularities, arousal and emotions in mediating the effects of music on subsequent cognition, the present study explored if brief listening to music might produce a subsequent transient change of verbal functions. A large sample (n 448) of younger (mean 28 years) and older (mean 72 years) individuals were studied to represent different background abilities. Verbal working memory (WM) and phonologically cued semantic retrieval were assessed using the forward digit span test (F DST) and word fluency test (WFT) To account for arousing, emotional and previous expertise effects, F DST and WFT scores were measured only in non musicians after listening to novel (unknown) excerpts of three different composers (Mozart, Vivaldi and Glass) and after silence, with individual preference for each condition subjectively rated. It was found that brief exposure to music had no beneficial effect on verbal WM, with even a transient impairment emerging after Vivaldi. In contrast, Vivaldi's excerpt induced a marked enhancement of word fluency, but only in young adults, whereas listening to Mozart's composition was followed by decreased WFT scores in the two age groups. These results show that depending on composer or excerpt specific music features, listening to music can selectively facilitate or inhibit ongoing verbal functions. It is suggested that these effects are mediated by pro active priming or interference of residual activations induced by music in working memory loops.

title: UWB radar cross section reduction in a compact antipodal Vivaldi antenna
abstract: This paper presents the design of a compact antipodal Vivaldi antenna (AVA) with reduced radar cross section (RCS) for directional UWB communications. The impedance characteristics of a conventional AVA are improved by introducing a BALUN taper in the ground plane and circular slots of different diameters in the wings of the AVA. The slots on the wings improve the RCS performance of the antenna by rejecting the orthogonal radiations from the AVA. Furthermore, drills of suitable diameter are introduced to further enhance the monostatic RCS performance. The proposed AVA offers 74% size reduction compared to the existing AVAs reported in literature with its bandwidth extending from 3 GHz to over 12 GHz. The prototype AVA is fabricated and the simulation results are verified using experimental measurements. The prototype antenna offers at least 11 dB reduction in RCS throughout the operating bandwidth with a peak reduction of 16 dB at 7 GHz and 11 GHz.