UWB Planar Monopole Antenna with Multi-Band Notching for High Data Rate Applications

International Journal of Advanced Science and Technology Vol. 29, No. 8s, (2020), pp. 3640-3649

Karthikeyan. R, Assistant Professor, [email protected] Kumaraguru College of Technology, Coimbatore Karthik.S, Assistant Professor, [email protected] Kumaraguru College of Technology, Coimbatore

Abstract A compact planar UWB monopole antenna (30*30*1.6mm3) with Tri-band notching characteristics is proposed in this paper. The antenna proposed resonates for the entire UWB Band(3.1GHz to 10.6GHz). Incorporation of slots are achieved in the structure to notch the three different licensed bands WLAN (5.2- 5.9GHz), WiMAX (3.3-3.7GHz) and Satellite NATO H band (6-8GHz) operate within UWB band. This antenna suits for interference free high date rate UWB applications. Gain enhancement is achieved by incorporating a cut at the ground plane exactly backside of the feedline - radiator meet point. The HFSS software tool has used to design the antenna. Fabrication is done and the tested results are compared with existing design. Keywords: Planar UWB monopole antenna, Band rejection, WiMAX, WLAN, H band, Reflection coefficient.

I INTRODUCTION For wireless communication, FCC announces the use of UWB band is license free in 2002 allows us to use as unlicensed manner [2]. This system provides the advantageous of miniature size, low power, maximum data transmission and cheap. For a past decade, numerous type of antennas have been proposed for the UWB Band. Recent researchers were reported the several results to achieve high gain with wider occupancy bandwidth. This has been brought due to personal communication devices aiming to provide image and high data rate system ubiquitously. Microstrip patch antennas have low profile integration with many equipment. The disadvantages of Patch antennas are low bandwidth and gain. In some applications higher bandwidth is required. So it is desired to improve the needs by incorporating monopoles into the UWB technology. The planar monopole has attracted to attain low profile, small size and easy to integrate in the place of wireless devices or radio frequency (RF) circuits. Parallely good efficiency and acceptable radiation properties are also expected in the UWB range. In time domain good impulse with low distortion is also expected[1]. The current distribution in monopole antenna elements are mainly concentrated over outer portion hence center portion can be removed to notch certain licensed bands[14]. Bandwidth can be enhanced with several techniques like modified ground structure with circular patch, using inset feed and stubs. In the elhabchi’s et al [15]work, a triple band notched antenna was designed with a dimension of (42*24*1.6 mm) and extended U slots been defected over the ground plane. A semi arc shaped slot was introduced on radiating patch to notch some bands like WiMax, WLAN and X band rejection. Variation of slot positions over the radiator implies a change on individual band notch throughout the frequency of operation. In Mewara et al design of monopole antenna[5], M shaped strip are embedded at the center and connected with feed line of rectangular strip (1*4mm). Slots are introduced for notching. The gain corresponding to the eliminated frequency band is minimized in comparison with the monopole antenna. A monopole candidate by Xiaoyang[6] gave a solution to triple band notch using modified Complementary split ring resonators (CSRR) to be etched inside the inner patch with overall size of (18*21mm2). Meanwhile, the position and size of the co-directional CSRR control the notching characteristics. The ground has been modified with a half circular cut on upper edge to enhance wider

ISSN: 2005-4238 IJAST 3640 Copyright ⓒ 2020 SERSC International Journal of Advanced Science and Technology Vol. 29, No. 8s, (2020), pp. 3640-3649 bandwidth. Results obtained through this design guarantee a VSWR of less than 2 from (2.5 to 13.9GHz) with triple unwanted band notches (VSWR>8). Various techniques are found by researchers to reject certain band of frequency involves slots of various shapes over patch and ground[7],[8],[9], inserting stubs in the patch or at ground plane[10],[11], use of metamaterial structures namely CSRR,SRR[12],[13],[17]or by making defective/meandered ground surfaces. Multiple single antennas are assumed to be transmitting simultaneously towards hundreds of antennas in MIMO systems[3].Through Venkata et al’s structural design[9] ,the planar UWB antenna of (27*25mm2) in specific to tri-notch band characteristics was observed. Impedance bandwidth ranges between 2.9 and 10.9GHz having return loss less than 10dB with tri band notches. In order to make the antenna resonate all the three bands (i.e) WLAN, WiMAX and HiperLAN, we compromise the two arms with the help of a neutralization line[4]. In the recent work of ours, a structure with a triple band notched nature of antenna in the UWB domain has been designed and discussed in Section III. Design simulations are carried out on High Frequency Software Simulator (HFSS) tool. Eventually, the results of proposed antenna under simulation and measured through Vector Network Analyzer (VNA) being discussed in Section IV.

II METHODOLOGY UWB Monopole antennas are the predominant key in the field of high data transmission applications. Nowadays, the area given to RF circuits are minimized and allow to develop effective results within that spacing. The proposed antenna is simulated using standard FR4 substrate with dimensions 30*30mm, 1.6millimeter thickness. The design starts with the structure of a rectangular radiator with added semi-circle at upper edge and two staircase shaped part in the edge where the feed is done. A feedline with an impedance of 50ohms is used. The UWB monopole antenna structure is shown in Fig (1). The optimized dimensions are given in the table [1]. The impedance characteristics (S11Vs Frequency) of the proposed antenna is given in fig (4)& (5).

Fig (1) –Single UWB Monopole antenna

Table 1 – Optimized Dimensions Figure Size Figure Size(mm) Indication (mm) Indication L 30 W1 2.6 W 30 W2 3 R 10.5 W3 2 g 0.4 W4 2 L1 12 W5 3

L2 9.8 L3 1 L4 2

Fig (2) –Front side

Fig (3) - Back side

Fig (4)–Frequency-S11 plot

Fig (5)- Frequency -VSWR plot

Fig (6) – Gain in dB From the impedance characteristics plots of the proposed monopole antenna (i.e)fig (4) & (5) it is inferred that the antenna is resonating for the entire UWB spectrum. Fig (6) is the 3-D radiation pattern. III PROPOSED ANTENNA To achieve the notching characteristics, slots are incorporated in the radiating element of the above said monopole antenna. Three different slots are introduced in order to notch the three different licensed bands operating in the UWB spectrum.

1) Inverted U-Shape Slot: This slot is the longest one used to notch the WiMax (3.3-3.7GHz) licensed band. This slot is incorporated in the leading edge side of the radiator. The dimensions of the slot are given in table (2). The monopole antenna is given in fig (7).

Fig (7) – Inverted U Slot incorporated monopole

2) U-Shape slot: Another slot (U-Shape) is incorporated at the center of the radiating element in order to notch another licensed band WLAN (5.2-5.9GHz).The dimensions of the slot are given in table (2). The monopole antenna with U-Shape slot is given in fig (8).

Fig (8) – U Slot incorporated monopole

3) Feed-Line Narrow U-Slot: Third U-slot is incorporated in the feed-line of the monopole radiator in order to notch the third licensed band operating in the UWB spectrum which is satellite NATO H band (6-8GHz).The dimensions of the slot are given in table (2). The monopole antenna with feed-line narrow U-Shape slot is given in fig (9).

Fig(9) - Monopole antenna with feed-line narrow U-Slot

The impedance characteristics i.e (S11 Vs Frequency) of the above said three different structures are simulated and the plot is given in fig (10).

Fig (10) – S11 Vs Frequency plot of structures.

The dimensions corresponding to the slots are given in table[2].

Table [2]– Dimensions of the slots

Parameter Size Parameter Size(mm) (mm) L5 7 W8 7.3 L6 5.5 W9 2 L7 0.85 W10 0.6 L8 6.2 W11 0.75 W6 13.5 W12 0.35 W7 2.7

IV EQUATIONS FOR THE SLOT DESIGN

----- (1)

----- (2)

To get notching, capacitance loading to be played in radiator plane i.e., the slot cut with the length in terms of guided wavelength is calculated using the below equations. -----(3) (or)

----- (4)

V RESULTS a. Simulated Structure of the Tri-Notch Antenna:

Fig (11) – Tri-Notch UWP Planar monopole

The dimensions are listed in the table (2).

b. Impedance Characteristics:

Fig (12) S11 Vs Frequency Plot

Fig (13) VSWR Vs Frequency Plot

c. 3-D Radiation Pattern with Gain

Fig (14) 3-D Radiation Pattern along with Gain.

d. Fabricated Image

Fig (15) Fabricated image

e. Measured Results using Vector Network Analyzer(VNA)

Fig (16) S11 Vs Frequency Plot Obtained using VNA

f. E & H Plane Radiation Patterns

Fig (17) E-Plane Pattern

Fig (18) H-Plane Pattern

g. Results Comparison

Table [3] – Simulated and Measured Results Comparison Notching Simulated Measured bands results results using Notched BW VNA (GHz) Notched BW (GHz) WiMax 3.3-3.9 3.4-3.9 WLAN 4.9-5.6 4.7-5.4 NATO H 6.5-8.0 6.5-7.6 band

The complete details of the proposed antenna’s simulation, fabrication and testing is discussed above. The comparison table for the simulated and tested results are given. The measured & simulated results are much close to each other and the expected notching is achieved.

VI CONCLUSION A tri-notch UWB antenna is presented. The incorporation of slots corresponding to the notching bands are discussed in detail along with the mathematical background.

This antenna serves better for UWB transceivers compared to the notch-free antennas which works in the environment where other (licensed band) wireless transceivers operate.

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