Study about Metamaterials Inspired Miniaturized Phi-shaped Antenna

A number of loop antennas designed to operate at UHF ISM band 2.4-2.5 GHz have been investigated. Four types of loop antennas were designed and fabricated including the circular wire loop, square loop, circular plate loop, and disk loop. The circular plate loop has been incorporated into the RF sensing and detection peripheral due to its excellent practical performance. It was examined in various types of wireless environments where the complex object/ material both conductive and non conductive existed. In this paper, each type of antennas was also tested, numerically and experimentally, to obtain its individual electrical properties such as S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> , VSWR, and radiation pattern.

A quarter-wave dipole antenna is typically used in portable transceivers of cellular personal communications systems. As a result of an omnidirectional radiation pattern of such an antenna a considerable part of the emitted power is absorbed by a user's body, especially by the head. Small handset antennas with a relatively wide bandwidth and minimized radiation pattern towards the user's head are presented in this paper. Two types of microstrip antennas i.e. dipole and patch antennas are considered. The results of experiments confirm that compromise between the requirements for radiation pattern and human head protection is possible and consequently, such types of antennas can be used effectively for mobile communications.

Sensors such as phased array radars play a crucial role in public safety. They are unavoidable for surveillance, threat identification and post-disaster management. However, different scenarios impose immensely diverse requirements for these systems. Phased array systems occupy a large space. In addition, if different antenna systems are needed for each function, the space required can be considerably large. For transportable platforms, such as ships and aircrafts, space and weight are critical parameters. Therefore, reconfigurable multi-band antennas are very attractive solutions for future multi-function sensor systems. Within this research work three different approaches are investigated to realize antennas for reconfigurable phased arrays. Wideband antenna designs constitute the first approach. Integrating this type of antennas with frequency selective filters provide the opportunity for fine tuning within one radar band. The wideband operation of the antenna is achieved by the blind-via feeding section and the quasi electric-magnetic radiating structure. The second approach involves the design of an antenna element with p-I-n diode switches. The switches are used to alter the antenna structure and thereby the operating frequency. Measured results verified the frequency reconfigurable capability of the antenna within L/S radar bands with frequency ratio more than 2:1. The planar structure, the back feeding mechanism, the compact size and the simple bias network made the proposed antenna suitable for array applications. The large frequency ratio and its usability in phased array applications made the design novel. Furthermore, for these frequency reconfigurable elements, a unique multi-scale array structure is introduced which can assure wide angle scanning for both frequency bands. The advantage of this novel array configuration is twofold: reduce the mutual couplings in the lower band, and increase the scanning volume for the higher band. A planar array demonstrator validated the proposed concept. In the third approach the operational band of an antenna is tuned by variable-impedance matching. In this study, the standard 50 ? matching is avoided and many advantages of variable-impedance matching are demonstrated. First, the principle is verified by tuning the frequency band of a microstrip antenna by an input-impedance tuneable CMOS RF-frontend. In the second design a novel dual-band E-slot antenna, with 2.5:1 frequency ratio, was designed. By changing the input-impedance the operating frequency of the antenna can be switched from L- to S-band. Variable-impedance matching provides few other advantages to phased array antennas. A scan-angle dependent impedance matching will assure low reflection coefficients for the entire scanning volume. On the other hand, it will reduce interfering and jamming signals coming from adjacent angles. The outcomes of this research work have led to solid understanding of how we can realize frequency reconfigurable antennas for adaptive phased arrays. The results will be particularly valuable in developing future narrow or wide beam radar systems with frequency reconfiguration and angular filtering capabilities.

A new type of planar leaky-wave antenna with omnidirectional radiation is presented in this paper. The structure is formed by a periodic array of unitary cells with open-plates and defected-ground open-rings. The proposed type of antenna presents steering capability covering broadside radiation toward backward and forward directions. Antenna parameters and circuit analysis, including return/insertion-loss, radiation pattern, gain, efficiency, and unitary-cell model are all provided. Simulated and measured results are shown. The proposed type of antenna possesses the advantage of low profile and low cost, providing high design flexibility for the real applications.

This paper presents a compact split ring resonator metamaterial-embedded rectangular microstrip patch antenna. The inset-fed rectangular microstrip patch antenna (RMPA) resonates at 5.29 GHz frequency with return loss −12.108 dB is designed with applications in wireless communication. After then, RMPA is embedded with metamaterial split ring resonator. This metamaterial structure gives reduced resonant frequency and improved bandwidth along with good impedance matching. This technique also provides 27% reduction in size of RMPA. The proposed antenna is simulated using HFSS software, the prototype antenna has been fabricated and results are measured.

This paper discusses the experiment of measuring antenna radiation patterns using hardware and software that has been made previously. The antenna measured is the Half Wave Open Dipole antenna that works at VHF frequencies as Antenna Under Testing (AUT). The hardware used is Module-1 and Module-2 which have previously been tested for functionality, and the software is the Antenna Radiation Pattern application that is created using the Visual Basic programming language in the Microsoft Visual Studio package. Radiation pattern measurement experiments were carried out under various conditions, namely (1) without RF signals; (2) with RF signal and the position of the transmitting antenna is 0o with AUT; (3) with the RF signal and the position of the transmitting antenna at an angle of 90o to AUT; and (4) simulation of electromagnetic wave interference when making measurements. Based on the results of experiments conducted, it can be concluded that the Antenna Radiation Pattern application has functioned well and can describe the AUT radiation pattern. Future work of this research is the measurement of radiation patterns for other types of antennas and refinement of applications for the measurement of various antenna parameters.

Partial discharge (PD) is the causes of the fault to occur in high voltage equipment due to the breakdown of the insulation system happen on equipment, even old equipment or new equipment. The PD in transformer oil is one of the significant causes of insulation failure and a breakdown. Hence, a sensor is needed to continuously monitor and detect the PD at an early stage on the power transformer. An antenna is one of the sensors that can be used to detect PD based on ultra-high frequency (UHF) method. However, the size of the antenna is the main problem to be installed in the transformer tank. Thus, three types of antenna which are Moore, Hilbert and Peano fractal with the dimension of 10 × 10 cm is designed to operate in UHF range 0.3 GHz to 3 GHz to be able to detect the frequency of partial discharge signal generated by electromagnetic waves. The performance of the proposed antennas in terms of return loss, Voltage Standing Wave Ratio (VSWR) and radiation pattern are analysed and compared for PD detection on the power transformer. Based on the result, the fourth-order of Hilbert fractal antenna was found to be the best antenna for PD detection in power transformer at working frequency range from 0.72 GHz to 2.77 GHz. This antenna also has low threshold of return loss at -36.2 dB for the resonant frequency at 1.67 GHz and the value of VSWR is near to one which is 1.03. Lastly, the radiation pattern of this antenna is almost in hemisphere shape and the gain variation of all frequencies are nearly stable compared to the other types of antenna.

High Tc superconducting (SC) active antennas, which are new types of antennas with a use of active properties of high Tc superconductors, are investigated. The SC active antennas were made from Y-type thin films, which were prepared with magnetron (sputtering) method. As for detections of electromagnetic waves ( f=9.55GHz, f=50.4GHz and 474THz), the sensitivities of the SC active antennas were found to depend on polarizations of radiated electromagnetic waves, applied currents, the annealing temperature, the strength of electromagnetic waves and structures of antennas et al.

We assess the potential error in measurements of the power transfer function corresponding to a reverberation chamber set-up when different antenna types are used for the reference and device-under-test measurements. We derive a mathematical description of the transfer function that accounts for differences in the amount of unstirred energy, represented by the spatially averaged K factor, arising from various antenna types. Our results show that loaded chamber configurations, combined with reference/device antenna pairs having significantly different radiation patterns, can result in statistically significant errors in the prediction of the transfer function. If it is possible to obtain an estimate of the K factor associated with the device antenna, this correction can improve the estimate of the transfer function that would be experienced by the device under test. Finally, we develop a method that could be used in standardized test methods to bound the uncertainty associated with the unknown K factor for common antenna types.

A Wireless Sensor Network (WSN) is a collection of various sensor nodes in a network capable of sharing information via wireless media. The type of antenna used is considered one of the main factors affecting WSN performance. Therefore, this research focuses on designing a directional compact antenna for WSN communication at 2.4 GHz frequency. This research used yagi uda as a patch antenna structure to suit gain and radiation patterns. Then, it was miniaturized using a meander line so that the antenna has a smaller dimension. As a result, this antenna worked at 2.4 GHz with <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$60 \text{mm} \times 58 \text{mm}$</tex> dimensions, 20% smaller than the initial dimensions. The parameters resulting from the design simulation were S11 -32.82 dB, bandwidth 210 MHz, gain 7.452 dBi, and directional radiation pattern.

This paper presents novel compact dipole antennas based on forward-coupling configuration of multilayer ring resonators (MRR) structure. The antenna consists of two conductive square open loops. The frequency of operation can be varied through the coupling between the two rings. This is achieved by changing the distance between the two radiating elements. Hence, these types of antennas are simply tunable. The structure is so versatile that a class of new antennas can be developed using this technique. The radiation pattern is bidirectional with a peak gain of 2.8 dBi. A good impedance matching and return loss better than 35 dB are obtained. Simulations have been carried out and the S-parameters, VSWR and radiation patterns are presented.

Lens antennas are a promising device for realizing the anti-collision radars needed in intelligent transport systems (ITS) and multibeam antennas for satellite communication. They have simple structure, high gain and no feed blockage. Especially if the operating frequencies are above the microwave band, the resulting apertures with several tens of wavelengths, become practical. In advance ITS application, the antenna is expected to resolve several objects in azimuth plane. In satellite application, the terrestrial station should catch multiple satellites at various directions. These applications demand multibeam antennas. Typical antennas with multibeam attributes include the dual-reflector bifocal antenna (Rao, 1974). Another proposal is the bifocal lens (Brown, 1956), its multibeam characteristics has been evaluated (Peebles, 1988). Multibeam antennas have to form high gain and low sidelobe radiation patterns at different directions. The bifocal lens is guaranteed to equalize the aperture phase distribution on the specified design directions in the scanning plane. However, it is not guaranteed on the transverse plane due to its astigmatism, and no previous report has adequately addressed the design issues, especially the resulting degradation of the radiation pattern. Another multibeam lens antenna is the Luneburg lens (Luneburg, 1964). Though it offers many focal points at arbitrary directions, it has manufacturing problems, tapered dielectric constant, and heavy weight. Our solution is to propose an effective method that optimizes multibeam lens antennas by gain, beamwidth, and sidelobe level. Antenna designs based on GA are very attractive and various methods have been proposed (Altshuler & Linden, 1997; Jones & Joines, 1997); we have already proposed a Yagi-Uda antenna design based on the pareto-GA (Kuwahara, 2005). This chapter presents the design of a multibeam lens antenna based on the pareto-GA. The coordinates of the lens shape and the feed position are given as variables and are associated with GA chromosomes. From the variables, the radiation patterns are calculated. The values of the objective functions are evaluated from the radiation pattern. The objective functions are given as the gain and the sidelobe level on the scanning plane and the transverse plane. To balance these objective functions, we adopt the pareto-GA (Fonseca & Fleming, 1993). In the pareto-GA, individuals are ranked through multiple objective functions and selection 18

Substrate integrated waveguide (SIW) technology that combines 3D and 2D structures has been successfully utilized due to its notable advantages, including in its application to H-plane horn antennas. As this type of antenna is commonly constructed on thin substrates, the E-plane radiation pattern is always wide, thereby limiting the achievable gain performance. In this work, we propose an approach that incorporates 3D printed horns on a prefabricated SIW H-plane horn antenna to successfully narrow the E-plane radiation pattern, thereby improving the gain performance. The proposed E-plane horn is designed at the aperture of the original H-plane horn, providing a smooth and continuous wave transition from the thin substrate to the end-fire direction. This approach improves the directional radiation performance significantly and reduces fabrication time and associated difficulties as the parasitic structures are simply attached to the SIW horn, without the requirement of redesigning or refabricating the original antenna. From 20 to 25 GHz, an optimized prototype shows excellent performance. At 22.7 GHz, it exhibits 35° and 33° for the E- and H-plane half-power beamwidths (HPBWs), with corresponding side-lobe levels (SLLs) of −23 dB and −15 dB. The present research reveals that the proposed design presents high feasibility and a reduced demand for high-precision manufacturing processes at a lower cost, concomitantly providing an effective means to further improve on the radiation characteristics.

The extensive demand for high-speed communication and connectivity has triggered the need for research in fifth-generation (5G) of mobile communication. The 5G evolution will not be limited to only mobile phones but also provide seamless connectivity through the internet of Things (IoT) in services like smart cities, smart homes etc. The clear intention of the 5G technology is to provide a vast capacity of network, a higher speed of multiple Gigabits per second, and enhanced dependability with negligible latency and stable radiation. This goal will not be possible without an efficient antenna structure. Numerous 5G antenna designs have been put forth so far by various researchers, but a thorough analysis of the various types of antennas and the techniques of 5G used to improve their performance is required to select an appropriate design for a particular application. The most recent research on the various antenna types and performance improvement methods for 5G technology is presented in this review study. This study is an effort to comprehensively examine the various types of 5G antenna structures, their performance optimization methodologies, comparison, and potential future advancements.

A wireless link was created using two identical antennas deposited on the substrate at the transmitting and receiving sides as shown in Fig.1a. To investigate effect of the environment existing between the transmitting and receiving antennas, several simulations were performed; one without any wired interconnections and other for different widths of the wired interconnections (w i ). The frequency range used for the simulations was from 20 GHz to 30 GHz. The result of simulations concerning the transmission gain between the transmitter and the receiver is shown in Fig. 2a. Note that the case of no wired interconnections is presented in Fig. 2a as w i =0. The distance between the two antennas (d) was assumed to be 10 mm in this case, as measured between the end-to-end antenna structures. It is clear from Fig. 2a that the transmission gain is larger than −20 dB across the band 21 GHz to 27 GHz for the case of no wired interconnection and between 22 to 28 GHz for the case of wired interconnection. The gain is at least 10 dB larger than the reported results in the literature when using other types of antennas, such as the monopoles, dipoles or zigzag dipoles [3]. This result indicates clearly the possibility of using the proposed antenna to establish a wireless interconnection even with packages that have a relatively large size. It is also interesting to compare the transmission gain with the conventional wired interconnections (when the wireless link is replaced by the wired link). To this purpose, the results published in [11] were interpolated. For a distance of 10 mm, the conventional wired interconnections described in [11] offered a transmission gain less than −28 dB at frequency of 25 GHz.