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Radio direction finding
Published in Laurie Tetley, David Calcutt, Electronic Navigation Systems, 2007
Other antennae are carefully designed to be highly directional. A simple example of this is a Yagi antenna, which is commonly used to receive television pictures and sound. In fact it is possible to use a Yagi antenna and its maximum strength signal indication, to determine the bearing of the transmitting station. Maritime RDF systems, however, use the properties of a simple loop antenna or an Adcock array, and produce a relative bearing indication from a zero or null signal strength.
Radio Frequency Utilization
Published in Gilbert Held, Wireless Mesh Networks, 2005
A yagi antenna commonly has one reflector and one or more directors, with the overall rating of the antenna being a function of its total number of elements. A yagi antenna can be considered to represent a directional form of a dipole antenna.
A Planar Printed Four-Element Pattern Diversity MIMO Antenna Based on Novel Quasi-Yagi Elements
Published in IETE Journal of Research, 2021
Quasi-Yagi antenna (QYA) is among the best candidates for directional radiation pattern because of its simple design, high gain, and wide impedance BW. Nevertheless, the QYAs developed so far, found very limited use in MIMO antenna system. The QYAs presented in [25,26] have used dipole as driven elements with complex BALUN structures, with a total size of 0.41λ02 and 3.01λ02, respectively. In [25], the antenna has achieved high isolation of 22 dB, but both the designs have narrow operational BWs. To avoid BALUN implementation complexity, the balanced feed is directly applied at dipole inputs in [27]. Proposed four-element MIMO antenna has achieved wide BW of 23.9% with isolation of 17 dB, however, the total size was 0.43λ02. In [28,29], the shape of the driven element is modified to a loop. Based on this three and four-element MIMO antennas are proposed. Yet, both antennas have large sizes and narrow BWs, which limits their use with size-constraints. Therefore, the design of a compact MIMO antenna system based on QYA elements is quite challenging. Recently, the QYAs are designed with monopole as a driven element to eliminate the need for a BALUN [30–32], but their applications in MIMOs are still unexplored.
A Compact Ultra-Wideband Planar Printed Bow-Tie Quasi-Yagi Antenna with Rhombus Director and Tapered CPS Connection Structure
Published in IETE Journal of Research, 2018
Figure 2 shows the design evolution process of the proposed quasi-Yagi antenna with same antenna size. First, a conventional micro-strip quasi-Yagi antenna with reduced ground plane size is shown in Figure 2(a). The simulated reflection coefficient and the realized gain of conventional micro-strip quasi-Yagi antenna are shown in Figure 3. It is observed that the impedance matching between 5.5 and 9 GHz is poor. In order to enhance the bandwidth of conventional quasi-Yagi antenna, a round-ended bow-tie configuration is introduced to the radiator and resonant cavity as shown in Figure 2(b). It is seen that a new resonant mode at 8.62 GHz is produced, and the gain is also increased slightly in high frequency ranges, which is due to increase in the radiated region. On the other hand, it is known that the tapered micro-strip line is often used to improve the impedance matching as an impedance transformer [17]. Thus, we utilize a tapered CPS connection structure between the bow-tie driver and balun to obtain a wide bandwidth, which means that the two end-line widths of the CPS are unequal. As shown Figure 3, the impedance matching and gain are significantly improved.
A Filtering Antenna Based on Etched Interdigital Structure for Dual-Band High Selectivity
Published in IETE Journal of Research, 2021
Xiaokun Yang, Ding Zhao, Zhengping Zhang
Quasi-Yagi antenna, a deformed structure from Yagi-Uda antenna, is one of the conventional antennas designed for various applications due to its exclusive end-fire and radiation-pattern characteristics [12]. Traditionally, it is generally consistent for researchers to design a common quasi-Yagi end-fire antenna on a cheap substrate composed of F4B with a relative permittivity of 2.65, thickness of 1 mm and loss tangent of 0.006 [13]. Therefore, a reflection coefficient of the initially designed quasi-Yagi antenna resonating within two bands from 3.6 to 5.5 GHz as the former band and from 12 to 14 GHz as the latter band are plotted in Figure 2 [14].