2 1.1 Introduction
Wireless and Satellite communication was spreaded all over the world at a very good speed in the last few decades, which provides greater flexibility in the communication sector of surroundings like in hospital, several factories, and many office buildings , . The IEEE c- band (4-8 GHz) and its slight variations contains frequency ranges that are used for many satellite communication transmission. The microwave frequency of the C-band performs better under adverse weather condition compared to other bands. WiMAX and WLAN are the standard-based technologies those enable delivering the last mile wireless broadband access . WiMAX is referred to as interoperably implemented IEEE 802.16 wireless-network standard that operates at higher bit rates over greater distance. It has the capability to operate in 3.4-3.6 GHz frequency ranges and at 5.5 GHz band  too. Whereas recently WLAN standard, those lies within the range of 2.4-GHz is emerged in market. And the data rates supported by this type of system are limited up to few Mbps. On the contrast, a no. of standards that had defined in the range of 5-6 GHz allow the data rates higher than 20 Megabits per second, which offers better solution for real-time imaging, multimedia, and high-speed video applications. But for achieving all the necessary applications a high performance wide bandantenna is needed including best ever radiation characteristics . During the last few decades, dielectricresonator antennas are widely accepted for several advantages i.e.
1.4 Scope of the Research
This research focuses on the design of high-gain switchable DRA array that is suitable for 5G applications requirement as stated in section 1.1. A high-gain switchable DRA array, consists of switchable DRA subarray and power divider network that is being integrated with switched-line phase shifter. In order to develop a high-gain switchable DRA array, the scope of this research is divided into three parts, which is single element DRA, switchable DRA subarray and high-gain switchable DRA array. Prior to that, various investigation on different feeding techniques of the single element DRA excited in the higher-order mode are studied at frequency 28 GHz. However, when the DRA is mounted on a ground plane, only odd mode can exist in the z-direction of DR. Therefore, mode 5 (T E 1δ5 y ) in the z-direction is used to investigate the different feeding technique for DRA after considering mode 3 is nearly to the fundamental mode (T E 1δ1 y ) . Three techniques of the feeding structures, which is microstrip line (ML), microstrip slot aperture (MSA) and open-end coplanar waveguide (OECPW) are designed, simulated and optimized. The studies are carried out in order to identify the best feeding technique that is most appropriate for 5G requirements in terms of bandwidth, radiation pattern and gain of the single element DRA especially those excited in the higher-order mode. The design, simulation and optimization process are performed using Ansoft High Frequency Structural Simulator (HFSS) ver. 16.0.
In wireless communication technology, a number of new developments have led to improved wideband characteristics, improvement in isolation, good polarization diversity, orthogonality performance, and design of simple structures. These structures support WiMAX (5.48–5.74 GHz), UWB ranges (3.1– 10.3 GHz), ITS (5.84–5.92 GHz) for single platform vehicular communication, and WLAN (5.14– 5.34 GHz & 5.72–5.82 GHz). Various dual/tri-feed/quad feed/multi and single band antennas have been observed [1–25]. Planar UWB easily extendable arrayantenna is operated at a frequency 3.1– 16.0 GHz producing a gain of 4 dBi, and ECC is 0.025 with an occupied area of 38 × 90 mm 2 . By using split-ring resonator (SRR) polarized MIMO analysis shows a low ECC around 0.001 while with a compact antenna area 40.5 mm × 40.5 mm , S 12 is greater than − 20 dB. In , a slot antenna
This work shows a varactor controlled rectangular slot coupled frequency reconﬁgurable cylindrical dielectricresonatorantenna. The bias voltage applied to the varactor loaded CDRA can provide a dynamic frequency tuning. The resonant frequency of the antenna can be tuned from 4.75 GHz to 4.96 GHz in the lower band (having a 10 dB impedance bandwidth of 8%), and the upper band changes from 6.31 GHz to 6.40 GHz (having a 10 dB impedance bandwidth of 21%) as the varactor diode capacitance is increased from 1 V to 5 V. The shift in the dual resonance tuning and tuning of both lower resonance and higher resonance is obtained by changing the slot position. The application of the proposed antenna includes a wide range of applications in C-band such as satellite communication systems, weather radar systems, Wi-Fi, and ISM bandapplications. The C-band is known to perform better for satellite communication in adverse weather condition.
The antenna is characterized as a metallic device for emanating (or) accepting radio waves . The array is nothing but the systematic arrangement of comparable objects, often in lines and segments. The antennaarray is an arrangement of at least two (or) more antennas. Numerous applications require radiation characteristics that may not be accomplished by a solitary component along these lines, so array antennas are utilized . A reflector is a specific intelligent surface used to divert light towards a given object (or) scene. Reflector antennas give correspondence over substantial measurements . A reflector arrayantenna is a kind of directive antenna in which different driven components mounted on a level surface used to mirror the radio waves in the desired direction. Reflectarrays have gotten substantially more interest since they joined the advantages of reflector antennas and phased arrays  . The advantage of using reflectarray rather than that of a reflector is, it is easy to fabricate, less weight and the scanning ability is high   . Antenna reflectors can exist as an independent gadget for diverting radio frequency energy. The scope of mm band is from 30GHz to 300GHz. Because of the high frequency of millimeter waves and their spread qualities make them helpful for applications including a huge measure of PC information, cellular communications, and radar. The explanations behind utilizing mm band are since there are a few restrictions in the lower frequency bands. The confinements are, the data transmission will be less on account of s-band, needs a bigger satellite dish on account of a c-band, just a little portion (1.3GHz-1.7GHz) of L-band is designated to satellite communications and for the most part of military utilize very little business offerings in x-band. The applications for mm band are scientific research, broadcast communications, weapon framework, security screening, thickness gauging and drug.
Engineering, Universiti Sains Malaysia, Penang 14300, Malaysia Abstract—A 1 × 3 element linear array using cylindrical dielectricresonator antennas (CDRAs) is designed and presented for 802.11a WLAN system applications. The top and bottom elements of CDRA array are excited through the rectangular coupling slots etched on the ground plane, while the slots themselves are excited through the microstrip transmission line. The third element (i.e., central CDRA) is excited through the mutual coupling of two radiating elements by its sides. This mechanism enhances the bandwidth (96.1%) and gain (14.3%) as compared to aperture coupled technique. It is also observed that the side lobe levels are reduced over the designed frequency band. Using CST microwave studio, directivity of 10.5 dBi has been achieved for operating frequency of 5.6 GHz. Designed antennaarray is fabricated and tested. Simulated and measured results are in good agreement. The equivalent lumped element circuit is also designed and presented using Advanced design system (ADS) for this proposed array.
The interest in dielectricresonator antennas (DRAs) for a variety of wireless communications systems has grown in the last few years [1–8]. Dielectric resonators (DRs) are fabricated from low-loss dielectric materials, for which the resonant frequency is predominantly a function of size, shape and permittivity. DRs oﬀer the advantages of small size, low proﬁle light weight, and high radiation eﬃciency, which make them attractive for many wireless applications [9–13]. A recent trend for DRA design has been in meeting Ultra-Wideband (UWB) speciﬁcations, and high data-rate wireless LANs, as well as applications in radar and imaging systems [14–17]. Various bandwidth enhancement techniques have been applied within DRAs using diﬀerent excitation mechanisms to excite several modes covering wider bandwidths. In the last decade, there has been a growing need for broadband antennas that can satisfy the entire frequency range of future UWB systems with a reasonable performance. Recently, UWB has been used widely in applications such as radar, telemetry, navigation, biomedical systems, mobile satellite communications, the direct broadcast system (DBS), global positioning systems (GPS), and remote sensing. The design of an appropriate antenna for these systems is one of the most important current challenges .
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in this work we present a 16x1 array’ elements of a high gain Novel shape designed DielectricResonatorAntenna (NDRA), having a low dielectric constant value of 18, for wide band (WB) 24 GHz automotive Short Range Radar (SRR) applications. The proposed NDRA array is feed by an efficient microstrip network feeding mechanism and presents wide impedance bandwidth (426 MHz), high gain (20.9 dBi), high efficiency (96%) and directional radiation pattern at 24 GHz with narrow angular beam-width of 6.4°. Computed NDRA array results allow the proposed design to be practical for the next automotive radar generations. Parametric studies have been analyzed using the Finite Difference Time Domain (FDTD) method of the CST-MW time domain solver and results, of the optimal structure, have been validated by the Finite Element Method (FEM) used in HFSS electromagnetic (EM) simulator.
Abstract—A new reflectarray configuration is proposed for low-loss applications at millimeter waves. It is based on the use of dielectricresonator antennas (DRA) as radiating unit-cells. The phase response of the elementary cell is controlled by adjusting the length of a parasitic narrow metal strip printed on the top of each DRA. A 330 ◦ phase dynamic range is obtained for DRAs made in rigid thermosetting plastic (ε r = 10). As the antenna radiating aperture is non flat, an original low-cost fabrication process is also introduced in order to fabricate the parasitic strips on the DRA surface. A 24 × 24- element array radiating at broadside has been designed at 30 GHz and characterized between 29 and 31 GHz. The antenna gain reaches 28.3 dBi at 31 GHz, and the measured −1 dB-gain radiation bandwidth is 5.2%. The 3.2 dB loss observed between the measured gain and theoretical directivity is mainly due to the spillover loss (2.3 dB). The total dielectric and conductor loss is less than 0.9 dB.
roles in next generations of safety and autonomously driving projects.
Anti-collision automotive radar systems are divided into two categories depending on range and beam width: short range radar (SRR) and long range radar (LRR) as shown in table 1. The SRR category is covering the most of automotive radar standardized frequency bands (24 GHz, 26 GHz and 79 GHz) in Narrow Band (NB) and UWB. The 24 GHz band has attracted many radar systems applications, summarized in figure 1 (a, b), like ACC support with Stop & Go functionality, collision warning, collision mitigation, blind spot monitoring, parking aid (forward and reverse), Lane change assistant and rear crash collision warning [2, 9].
(a) Conventional Triangular patch antenna (CTPA) All the dimensions of the patch antenna have been calculated from the mathematical expressions  as given by equation (1),(2),(3) and (4). From Equation (1), side length of patch antenna is computed by making use of dielectric constant and given frequency. Effective dielectric constant is calculated by using side length from equation (2). Effective side length as well as resonant frequency by making use of side length and effective side length calculated from (3) and (4). Synthesized antenna performance is examined as per intended application. In Table 1, geometric design parameters triangular patch antenna (Fig. 1.) are given.
In this paper, the design and development of so called conventional type of microstrip patch antenna. The enhancing bandwidth and size reduction mechanism that improves the performance of a conventional microstrip patch antenna on a relatively dielectric thin substrate, is presented. The band with three resonant frequencies. band used in weather mapping and detecting, long –range band used in satellite communication, software used to simulate the antennas. Without any slot the simulated conventional microstrip patch antenna size has been reduced by 100% with an increased frequency
The eﬀects of using these three diﬀerent feeding techniques on reflection coeﬃcient and impedance bandwidth have been analyzed. The simulated results of scattering parameters are obtained using CST Microwave Studio Software 2014  and measured using vector network analyzer. Fig. 4 presents the simulated reflection coeﬃcient plot of the RDRA for the three feeding techniques. All three designs manage to operate at 28 GHz with an acceptable value of reflection coeﬃcient. Fig. 5 shows the simulation and measurement results of RDRA with the new feeding structure. Good agreement between measurement and simulation results is obtained for the RDRA with selected feeding. However, in terms of impedance bandwidth and gain, all three feeding techniques give a diﬀerent result. The summary of the simulated result of gain and impedance bandwidth is shown in Table 1. A microstrip line can provide a wider bandwidth, but the gain for a single-element antenna is low. Compared to aperture coupled feed, it can provide higher gain; however, the bandwidth is narrow. The new feeding structure aﬀords to have wide bandwidth and at the same time high value of gain for single element. The modified structure feed line has been tuned and optimized to operate in 5G frequency band around 28 GHz to support the DRA as a main radiator element in this design. Actually this feeding structure can excite fundamental mode of DRA and also has its own resonance but with a narrow bandwidth. As we can see in Figs. 5 and 6, the DRA bandwidth is greater than the covering range from the feeding line. It must be noted that the first resonance is from feeding line and the second resonance from DRA which operates at TE x δ11 mode.
of solutions indicates that the criteria can only be met inconsistently. The figure also exhibits points where the 90 percent confidence intervals are nearly convergent upon the mean value. This invariability suggests that despite deviation in the inclusion permittivity values between iterations, the ability of these systems to tolerate change is similar. Where the solutions exhibit sample means that are greatly in excess of the 5 percent tolerance and the confidence interval about the respective values are likewise surpassing the minimum tolerance value, the solutions are achievable. In contrast with the required tolerance for the inclusion permittivity, it has been indicated in the available literature that current fabrication techniques can achieve an accuracy of roughly 1μm for millimeter sized spherical dielectric inclusions. Furthermore, the melt cooling process for the micrometer range detailed previously is recognized as providing exceptionally high accuracy for certain glasses and ceramics . In this regard, the requirements for the electric inclusion, as depicted in figure 35, can be understood to designate these spheres as physically realizable solutions due to their sample mean values broaching either limit of the windowed space. This relative immutability is not shared by the magnetic inclusions and lattice constant whose allowable mean variation values trend towards zero for substrates with a higher permittivity. In consonance with these regions, the respective confidence intervals exhibit infinintesimal width; whereby it can be assumed that regardless of the sample solution utilized, the requirements on the transmittance cannot be met without perfect accuracy to the designed system. It should be mentioned that the boundary utilized in the algorithm can be redefined to incorporate null values of the magnetic mode coupling inclusions. Under this definition, the system would separately engage the electric field and therefore operate with an effective
The conﬁguration of the proposed dual-band CP DRA is shown in Figure 1. The DRA is made from a ceramic material with permittivity of ε r . The rectangular DRA, which has dimensions of a × b × c (a = b), is located at the center of a FR4 substrate. The FR4 substrate has a thickness of t and a side length of l g . The DRA is excited by a modiﬁed annular slot fabricated on the dielectric substrate. The
Abstract: This paper presents the development and characterization of dual band and 1×4 dual bandantennaarray on a flexible polymide substrate.In this paper we have presented the design of a dual band microstrip antenna which will be operating in the wireless LAN band and IEEE 802.11 a/b/g. Dual-bandantenna elements that support dual-polarization provide ideal performance for applications including space-based platforms, multifunction radar, wireless communications, and personal electronic devices. In many communications and radar applications, a dual-band, dual-polarization antennaarray becomes a requirement in order to produce an electronically steerable, directional beam capable of supporting multiple functions. In this paper a dual band microstrip antenna is designed and its measurement results in terms of S(1,1) parameters and radiation patterns are studied. Microstrip design equations are introduced and validated by simulated results. This antenna is implemented on polymide substrate with = 4.3, h=1.6mm and operating frequency 5.25GHZ. By this design it is also shown that dual band operation is possible with proper position of the feed line and proper determination of inset size. Designed antennas is simulated by Ansoft High Frequency Structural Simulator (HFSS) by using the FEM (Finite element method).
DRAs are commonly low gain antennas with a broad radiation pattern. As with other conventional low gain antennas, DRAs can be arrayed to acquire higher gain. Various types of feeding methods have been used to feed a linear array of DRAs to obtain this goal, such as microstrip lines , coplanar waveguide , slotted waveguide , and dielectric image line . Among these excitement schemes, aperture coupling with a microstrip feed line is mainly used because of ease of assembly, suitability to integrate with circuits, and isolation among the antenna and feeding network.
The computed and experimental return loss versus frequency is shown in Fig. 6 for the DRA with the small metallic patch. This antenna achieves a computed return loss of −28 dB at a frequency of 6.3 GHz and gives a 10-dB return loss bandwidth of 4%. Experimentally, the measured return loss as shown in Fig. 6 is −25 dB at a frequency of 7 GHz and the 10-dB return loss
DielectricResonatorAntenna has broad spectrum of dielectric materials to be used for intended application. This paper presents the review on past done work in the field of DielectricResonatorAntenna. After study of various research papers it concluded that by choosing proper structure for DRAs we can easily increase the bandwidth. Many different excitation schemes are available which helps to have greater efficiency and high directivity. Moreover, DRA doesn’t have metallic loss, so low-loss dielectric material can be useful for high radiation efficiency.
with thickness of 1.58 mm, loss tangent of 0.002 and dielectric constant of 4.4 has been taken for this design consideration. A power divider using a λ/4 transformer has been designed on the FR-4 substrate to feed the array. A coaxial line fed technique has been used, and the array is fed by a SMA connector through power divider.