Design and Analysis of a Tunable Rectangular Microstrip Slot Antenna for Narrow Band Internet of Things Applications at 1800 MHz

Introduction

The Narrow band Internet of Things (NBIOT) antenna has becoming a famous technology in making things automation as well as for the smart industries. Mainly the available operating frequency for NBIOT applications are from 825 MHz to 960 MHz (at lower band) and 1725 MHz to 1860 MHz (higher band). As per antenna theory for making antennas at low frequency required really high dimensional geometries. Hence in this chapter to propose the antenna for the higher band operating frequency of NBIOT (1725 MHz to 1860 MHz) has consider into account.

The fundamental idea of this chapter is to design and analysis of a simple antenna at less in the dimensions than (Zhuo et al., 2020) to satisfy the application requirements in the field of narrow band internet of things applications. In the literature many antennas has been proposed to achieve the narrow band application by using different shapes of slots on the patch surface to resonate antenna at desired frequency band such as U-shaped, G-shaped, P-shaped. But in this research a rectangular slot were introduced on the patch surface to make antenna to resonate at within the operating frequency band i.e 1725 MHz-1860 MHz. the significant difference of the proposed antenna with the literature is that the size of the antenna has been reduced 45.88% than (Zhuo et al., 2020). But (Zhuo et al., 2020) has the dual band operating frequency performance.

Many methods are available in the literature (Chou & Ku, 2015; Choukiker et al., 2014; Fan et al., 2012) to adopt a technque to create input feeding to the antennas such as coaxial line, microstrip line. In the proposed antenna a rectangular microstrip line has been used as a feeding method to provide the input power to the mounted antenna. Since the position of the antenna can be change easily in according to match or deal with impedance matching (Li et al., 2013; Li et al., 2016; Pan et al., 2005). As well changing of the feeding position is much simpler than the designing a co-axial probe feeding.

Later a tuning approach has been analysed based on the length of the patch and investigated its bandwidth and amount of transmitting power (%) under different lengths of the provided antenna. Later the influence of the slot on the patch surface has been investigated under different length and width of the slot structure to obtain a maximum power transmitting from the provided antenna patch. The provided observations are mainly focused on the power transmission improvement. As well the proposed antenna has positive magnitude gain at E-plane and H-pane.

The remaining of this chapter as follows as in section II. Design of the Proposed Antenna. III. Results and Discussions and IV. Conclusions.

Proposed Antenna Design

Initially a Rogers RT/duroid 5880 (tm) substrate has been created with length and width as 60 mm x 30 mm. The maintained height of the substrate is h. later with the same dimensions the ground has been created at the bottom of the dielectric material. Now, the perfect electric (PerE) conductor sheet has been patched as shown in Fig. 1. The all dimensions of the proposed antenna has been listed in Table. 1. The width and length of the patch has derived from the equation (1) and equation (3). Where equation (2) provides the effective dielectric for a chosen dielectric constant 2.2 and loss tangent 0.0009. mm(1)

](2) mmWhere, 𝜀_r = 2.2, h= height of the dielectric substrate.

C = velocity of light = 3×10⁸ m/sec.

b1= width of the antenna

L_eff = Effective length of the anticipated antenna

a = L_eff – 2∆L mm(3)

Figure 1.

The created antenna design on high frequency structural simulation.

Table 1.

The detailed dimensions of the proposed antenna (h= heigh of the dielectric medium).

S. No	1	2	3	3	4	5	6
Geometry	a	b	b1	c	c1	d	h
Values (mm)	53.98	25	19.78	2.17909	5	6.7	1.5748