Abstract
In this paper, a planar, compact pentagonal shaped ultrawideband antenna of microstrip line fed offering triple band-notched characteristics response is proposed and investigated. Triple band-notch response can be achieved by creating two inverted U-shaped slots of different size in pentagonal patch, and also electromagnetic band gap structure of hexagonal shape is created near the feed line of UWB antenna. To implement the proposed antenna, RT/DUROID 5880 substrate of 1.6 mm thickness is used. The designed antenna was successfully simulated, developed, and manufactured. The dimension of the suggested antenna is and has a bandwidth of 3.1–10.6 GHz with a magnitude of , the maximum pass band gain of 4.6 dB and with the exception of the 4.0–4.4 GHz (C-band satellite communication), 5.2–5.8 GHz (WLAN), and 8.0–8.25 GHz (X-band) frequency bands. The suggested antenna has a good return loss, a virtually omnidirectional radiation pattern, and a constant gain throughout operation.
1. Introduction
In wireless and mobile communication, ultrawideband technology has been extensive incentive from academia and industry with a frequency band of 3.1–10.6 GHz for marketable wireless communication applications, and monopole antennas are more important in such applications. However, these structures are not planar; they are difficult to combine with microwave integrated circuits. As a result, printed monopole design variations are preferred. Rectangular, circular, triangular, sectoral, arc, and their modified forms are the most popular radiating patch shapes in UWB antenna design. Other narrow band services like WiMAX, IEEE802.16 (3.3–3.7) GHz, 3.7 to 4.2 GHz (C-band satellite communication), IEEE 802.11a, WLAN, HIPERLAN/2 with 5.15–5.825 GHz, and ITU with 8.02–8.4 GHz bands exist over the specified range of UWB spectrum 3.1–10.6 GHz. The fundamental concepts of microstrip patch antenna, antenna parameters, the range of best suited values to design an antenna, basic concepts of UWB antenna, and the effect of material used in the antenna on antenna parameters are explained in the paper [1]. Filters are used in some UWB antenna applications to reduce these frequency regions. Filters, on the other hand, add to the complexity and cost of an antenna design. As a result, UWB antenna with eliminated frequency bands is required to diminish the likelihood of interference. In the UWB band, a variety of structures such as slots/EBG structures have been described for notch frequency response [2]. One of the traditional methods is cutting of slot(s) with various shapes on the radiating patch including a feeder-embedded slot line resonator, embedding stub(s) along with radiating patch, using split ring resonators (SRRs), and embedding slots in the ground plane integrating electromagnetic band gap structures (EBG) [3, 4]. Zhu et al. have developed an antenna size of by placing two flexuous slots and a C-shaped slot on the patch and the antenna ground plane, respectively, to achieve 3.5/5.5 GHz twin band-notched characteristics [5]. Thomas et al. have implemented planar ultrawideband bevelled UWB with CPW fed with size of an impedance transformer along the feed line and the design has on FR4 substrate ( of 4.4 and thickness of 1.6 mm), and this design shows a bandwidth of 8.4 GHz, i.e., from 3.0 to 11.4 GHz, gain of 1.85 dBi, and radiation efficiency is greater than 81% [6]. Haraz Ahmed and Sebak have explained about the antenna with a slit ring resonator (SRR) to notch band of 830 MHz, i.e., 5.0–5.83 GHz for WLAN from the frequency range from 3 GHz to 13 GHz [7]. A UWB antenna with dual band elimination characteristics was achieved by placing U-shaped slot [8] and also embedding both C-shaped and U-shaped slots [9] with improved in the gain. Mandal and Das have investigated on dual band-notch UWB antenna by introducing EBG structures in place of slots and achieved dual band notching with in UWB frequency range, and this design has improved the gain [10].
The authors Kumar and Masa-Campos have implemented a dual polarized UWB antenna [11]. Jaglan et al. have designed an antenna using EBG structures of mushroom type and uniplanar to create band notching in for WiMAX band of 3.3 GHz–3.8 GHz, WLAN band of 5.15 GHz–5.825 GHz, and 7.1 GHz–7.9 GHz for X-Band downlink satellite communication band within UWB band spectrum [12]. Deshmukh and Mohadikar have invented antenna size with of pentagonal patch with novel V-shaped holes and hexagonal cut EBG structures beside the feedline for dual band elimination of 3.7–4.6 GHz for C-band and 5.16–6.08 GHz for WLAN bands over the spectrum of 2.7–10.6 GHz having S11 is less than -10 dB and [13]. Yadav et al. implemented an antenna with a size of by placing SRR, S-shaped, and inverted modified U-shaped slots on a radiating patch to eliminate the bands of WiMAX from 3.3 to 3.6 GHz, C-band of 3.8–4.2 GHz, and WLAN of 5.1–5.8 GHz bands over 3 to 11 GHz with antenna parameters of apart from notched bands [14]. Guichi et al. have implemented new V-shaped radiating element with a staircase flaw with a 50 Ω transmission line as a feed for dual notch frequency spectrum of WiMAX of 3.17–3.85 GHz and ITU of 7.9–9.1 GHz within UWB frequency range [15]. Jose et al. have implemented a new type of double-elliptical-shaped MSA UWB antenna using HFSS Software [16]. Lv et al. have implemented an antenna with of 3.0 ~ 11 GHz using split-ring resonators (CSRRs), J type hole on the bottom side plate, the spiral type slot is loaded to create a band notching of 3.22 to 3.97 GHz, 4.94 to 5.84 GHz, and 7.25 to 7.86 GHz bands are accomplished [17]. Ghahremani et al. have implemented an UWB antenna by inserting slitted EBG structure and a defected ground structure (DGS) for dual band notching of WLAN/WiMAX [18]. Trimukhe and Hogade have developed an antenna by inserting fractal EBG and Two Via Edge Located (TVEL) EBG structures beside feed of antenna for creating a notching bands of WiMAX of 3.3 to 4.0 GHz, WLAN of 5.1–5.8 GHz and 7.2 to 7.8 GHz for satellite downlink communication of antenna size of using FR4 substrate to VSWR is less than 2 in the band from 2.9 GHz to 11.2 GHz apart from notched bands [19]. Kadam et al. have designed an UWB antenna on FR-4 substrate with the size of with the frequency spectrum of 2.7 GHz–10.6 GHz, the parameter values such as S11 less than 10 dB (VSWR ≤2), with the exception of 3.7–4.6 GHz (satellite C-band) and 5.16–6.08 GHz (WLAN) frequency bands [20]. The authors of this paper have designed fractal antenna of 5th iteration for UWB applications for better gain [21]. Din et al. have explained the gain improvement techniques in UWB antenna for GPR applications [22]. Kumar and Masa-Campos have designed dual polarized UWB antenna for WLAN band notching [23], and the Wang et al. investigated UWB antenna for the elimination of Bluetooth/WIFI-7 and satellite communication bands in UWB frequency range [24].
In this paper, a modified novel inverted U-shaped slots with two different dimensions are inserted on the pentagonal-shaped UWB antenna, and hexagon-shaped EBG structure is placed close to the microstrip feed of UWB antenna. Primarily, a UWB antenna with pentagonal structure UWB is investigated for the frequency spectrum from 3.1 GHz to 10.6 GHz and antenna parameters such as return loss have being measured explained in Section 2. In Section 3, the UWB antennas with novel inverted U-shaped slots are created on the patch for dual band notched response at 4–4.4 GHz (C-band) and 5.2–5.8 GHz (WLAN). In Section 4, dealt with hexagonal shaped EBG structure characteristics and its applications such as band notching at 8.0–8.25 GHz (X-band) and improvement of gain due to EBG are explained. Section 5 explained about designed UWB antenna performance with and without EBG. Section 6 discussed about group delay parameter which indicates the performance of the UWB antenna and presented fabricated antenna performance by comparing the designed antenna. Section 7 explained the conclusion of the proposed work. In this article, the band-notch features are obtained in the lower frequency band by varying the length of modified inverted U-shaped slots. The proposed antenna is designed and fabricated on a low cost RT/DUROID 5880 substrate by using high-frequency structure simulator (HFSS) software. The tunable notch frequency band helps to reduce the intrusion with instantaneous applications such as Bluetooth, Wi-Fi, and Wi-MAX.
2. Pentagonal-Shaped UWB Antenna
Figures 1(a) and 1(b) illustrate a typical pentagonal shape UWB antenna developed on a low-cost RT DUROID 5880 substrate height, i.e., . The basic TM11 mode of the pentagonal shaped patch with side length is around 2.7 GHz, whereas the lower band of frequency is 2.92 GHz. The width of a microstrip fed is 2.6 mm of 50 ohm impedance has been chosen, supported by a ground plane with and . The horizontal gap in between the ground plane () and patch is set by 3 mm, resulting in the best bandwidth. The detailed dimensions of proposed antenna are as mentioned in Table 1. Figure 1 shows the simulated results of resonance and return loss (S11) characteristics for the frequency ranging from 2 to 11 GHz shown in Figure 1(c). Figures 1(d) and 1(e) illustrate the distributions of average surface current for the basic 2 modes of TM11 and TM21 of a pentagonal-shaped monopole antenna. The RT/DUROID 5880 substrate dielectric constant, i.e., , is due to the compensated ground plane of monopole antennas. Equation (3) is used to calculate two model frequencies for knm of 1.84118 and 3.05424. In equation (3), the word “c” signifies the free space velocity of the light.
The proposed formulation yields a near prediction of 2-mode frequency such as TM11 and TM21 with a percent of .
3. Pentagonal-Shaped UWB Antenna with Inverted U-Shaped Slots
A new pentagonal shaped ultrawideband antenna design with modified inverted U-shaped slots loaded on a radiating patch is chosen based on the surface current distribution in TM21 mode for band elimination application is shown in Figure 2(a). The position of slots will be disturbing impedance and also frequency range to attain reduced smaller notch band response. The impact of altered inverted U-shaped slots is first studied by examining the antenna’s resonance curve plot without a hexagonal EBG structure. The horizontal slot length is “Lh,” while the inclined slot length is “Lv” in the modified Inverted U-shaped slot. where Ls is the total slot length.
(a)
(b)
(c)
As a result of the proposed design of UWB antenna with novel inverted U-shaped slots without EBG, dual notched response is achieved at the frequency bands at 4–4.4GHz (C-band) and 5.2–5.8GHz (WLAN), respectively, and the return loss S11 of <-10 dB in UWB frequency range except notch bands is achieved as shown in Figure 2(b). The gain of the antenna in UWB range is as explained in Figure 2(c), and the gain is about 2 dB in the UWB frequency band except band-notching regions, i.e., at notching bands, zone negative gain was exhibits.
4. Hexagonal-Shaped EBG Structure and Its Characteristics
To reduce the interference further in the UWB band, hexagon-shaped EBG is embedded in the near the feed line of the antenna structure. The designed EBG unit cell structure is shown in Figure 3(a). The dielectric constant of substrate , height of substrate , side dimension of EBG cell of , and diameter of each via are the unit cell parameters. The rejected bandgap of presented EBG of hexagonal shaped can be seen in the dispersion diagram of Figure 3(b), such as between mode-1 and mode-2 is a band gap (gray section) centered at , lower cutoff frequency is & upper cutoff frequency is . To describe the process of the EBG connected to microstrip, a resonant equivalent circuit model of LC resonator was shown in Figure 3(c).
(a)
(b)
(c)
The equations of (4) to (6) as mentioned below are used to calculate the cut-off frequency of the band gap created by the EBG cell. A hexagonal-shaped EBG structure is incorporated near to the feed line of the antenna as shown in Figure 4(a) to create a band-notch response, and a cylinder is placed inside the hexagonal rings for notching and it acts as inductor in LC circuit.
(a)
(b)
(c)
Figures 4(b) and 4(c) explained about the return loss S11 versus frequency and gain versus frequency of the UWB antenna with EBG structure, respectively, the S11 is < -10 dB over the UWB band range except notch frequency band of 5.25 to 6.05 GHz, and it is observed that the gain is negative at the notch band range.
5. An UWB Antenna Design with Both Slots and EBG
A novel pentagonal-shaped UWB antenna loaded with two inverted U-shaped slots and EBG structure for triple band-notch response was designed using HFSS software as shown in Figure 5(a). Due to upper inverted U-shaped slot, the notch frequency band range of 4 GHz to 4.4 GHz, which is a C-satellite band was achieved. The lower inverted U-shaped slot helps to create a notch frequency band range of 8 GHz to 8.25 GHz which is an X-band. The hexagonal shaped EBG structure helps to create a notch frequency band with a frequency range of 5.2 GHz to 5.8 GHz i.e., WLAN (wireless local area network), and also EBG suppresses the surface wave and due to that there was an improvement noted in the parameters of S11 and gain of the antenna.
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(b)
(c)
(d)
(e)
(f)
(g)
(h)
The antenna parameters such as return loss S11 of <-10 dB entire UWB spectrum except triple notch bands were explained in Figure 5(b), the gain versus frequency of triple band-notch antenna was explained in Figure 5(c), the radiation pattern of UWB antenna at pass bands of 3.5 GHz, 4.5 GHz, 5 GHz, and 8 GHz was explained in Figures 5(d)–5(g), and the peak gain in the pass band was achieved around 2.58 dB.
Radiation pattern of the antenna is shown at pass band of Figures 5(d) 3.5 GHz, 5(e) 4.5 GHz, 5(f) 5 GHz, and 5(g) 8 GHz shows omnidirectional antenna properties where in , it is termed as E-field that shows the shape of “circle,” and in , it is termed as H-field that shows shape of “eight.”
Figure 5(h) shows the comparison of antenna gain with and without EBG structure, the black color graph indicates the gain with EBG, and the red color graph indicates the gain without EBG. The gain of an antenna is improved about 2.58 dB. Thus, the gain is increased due to placing of EBG structure near the feed line of the antenna design.
6. Performance Comparison of Fabricated Antenna with Designed Antenna
The proposed UWB antenna for triple band-notch response was fabricate on RTDUROID 5880 with 1.6 mm thickness as presented in Figures 6(a) and 6(b).
(a)
(b)
(c)
(d)
(e)
(f)
(g)
The result comparison with respect to S11 and group delay less than 2 ns were presented in Figures 6(c) and 6(d), respectively, and it is found that there was a good correlation results between designed antenna and fabricated antenna. The radiation pattern measurement setup is shown in Figure 6(e). The radiation pattern measurement of fabricated antenna at 3.5 GHz and 5 GHz was measured with help anechoic chamber as presented in Figures 6(f) and 6(g).
7. Conclusion
The proposed pentagonal-shaped UWB antenna yields bandwidth from 3.1 GHz to 10.6 GHz. The triple band-notch antenna with modified inverted U-shaped slots and EBG structure is designed and simulated, and physical antenna has been fabricated and tested for UWB band spectrum with band-notching characteristics. The antenna has successfully been able to eliminate the interferences bands of C band (4.0 to 4.4 GHz), WLAN (5.2 to 5.8 GHz), and X band (8.0 to 8.25 GHz) frequencies. The proposed antenna achieved a peak gain of 4.6 dB at 5 GHz. The proposed antenna exhibit omnidirectional properties. The experimentally measured results of designed triple band-notch antenna have shown a satisfactory agreement and consistent with the simulated results.
Data Availability
Data available and supported for finding this work. Data collected from various sources and research centers in the area of triple band-notch UWB antenna with slot and EBG structures.
Conflicts of Interest
The authors declare that they have no conflicts of interest.