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Heliyon
Heliyon
Heliyon
2405-8440
Elsevier

S2405-8440(24)13550-5
10.1016/j.heliyon.2024.e37519
e37519
Research Article
Design implementation analysis of multi-band antenna for terrestrial applications
Natarajan Porchelvi nporselvi008@gmail.com
a⁎
Sigamani Titus tituseee@krce.ac.in
b
a Vivekanandha College of Technology for Women, Tiruchenkodu, India
b K.Ramakrishnan College of Engineering, Trichy, India
⁎ Corresponding author. nporselvi008@gmail.com
05 9 2024
30 9 2024
05 9 2024
10 18 e3751921 9 2023
3 9 2024
4 9 2024
© 2024 Published by Elsevier Ltd.
2024

https://creativecommons.org/licenses/by-nc-nd/4.0/ This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
A multi-band antenna is proposed for terrestrial applications above 5 GHz. The design includes one director element, three split ring resonators (SRR), and a printed patch antenna on a FR4 substrate to make the miniature structure. The novelty is the addition of “C” split rings and one identical stub linked to the partial ground into the radiating element, which improves impedance matching and radiation characteristics across the target bands. The prototype is designed with five distinct resonance frequencies and radiation patterns compared to those produced by the patch, the director and resonators are added. Return loss simulation results and measured radiation pattern findings are validated and analyzed. The antenna produces a gain of 7.84 dB, overall efficiency of 84.76 %, and a VSWR of 1.8 at 7 GHz frequency, which is achieved due to the peculiar features of the FR4 and it is highly suitable for traditional communication. VSWR, gain, and radiation efficiency are all higher on this antenna than they are on a typical multiband antenna. At 20 GHz, the designed antenna band is efficient to operate with five dissimilar resonant frequency bands, pinpointed at 7.224 GHz, 10.723 GHz, 13.808 GHz, 17.014 GHz and 19.549 GHz through different impedance bandwidths.

Keywords

Multi-band antenna
Bandwidth
FR4
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pmc1 Introduction

The need for diverse antennas is expanding along with the use and advancement of radio, and so are the requirements for an antenna's performance. Recently, mobile terminal equipment has become more and more popular with multiband and small antennas [1]. The challenge of miniaturizing multiband antennas can be difficult since the antenna must be built to function effectively over several frequency bands while keeping a small size. Some of the challenges that can arise during the miniaturization of multiband antennas include the ones listed below: Radiation efficiency, mutual coupling, design complexity, and frequency bandwidth.

As a result, the relevant requirements for antenna performance have been designed using multiple feeding technologies [[2], [3], [4]], frequency selective surfaces [5], matching resonant technology [6], and plasma antenna technologies [5]. In terrestrial applications, different multiband antenna types, such as patch, dipole, and slot antennas, are employed. These antennas can be made to work on a limited number of frequency bands or on a broad spectrum of frequencies.

Different feeding methods have a particular impact on performance. For instance, the micro strip line feed mode has excellent antenna performance but a very limited bandwidth [[7], [8], [9]]. The strength of the antenna, which involves a large ground plan, must be balanced with the user's comfortability, which necessitates a small footprint, according to the antenna designers. Additionally, when the electrical size is decreased, the antenna's efficiency and bandwidth are decreased. It is suggested to circumvent the constrained bandwidth by utilizing a small frequency-reconfigurable antenna when the communication standard allows it. Thus, bandwidth will be immediately limited.

1.1 Motivation

The antenna construction may be complex, including layers made of high-reflectivity materials and having three-dimensional geometries that work well in a single frequency range and serve a particular purpose in unique applications [6,7]. An antenna that can work on numerous frequency bands is known as a multiband antenna. A miniature dielectric particle with a high permittivity has been used in a multi-band antenna in an optimization technique to achieve low-loss magnetic resonance [8]. Additionally, low-loss magnetic FR4 can be produced by suppressing radiation losses [9]. Super band frequencies have longer wavelengths and can pass through barriers better. Multiband antennas can assist reduce the size and complexity of devices by removing the need for several single-band antennas, in addition to enabling devices to connect to multiple frequency bands [10]. A dual-band meta material resonator with a single-sided triangular form and negligible loss was described. Additionally, a novel approach based on the multiple ring geometry for realizing a multi-band low-loss antenna with concentric open ring resonator inclusions was proposed in Ref. [11,12]. But in the previous research works demonstrated bandwidth enhancement which in turn affects the radiation properties, It is difficult to optimize the multi-band parameters.

The above limitations are overcome in this work by designing a novel, small, straightforward structure, cost-effective, simple to make, multi-band printed monopole antenna for terrestrial operations for prospective terrestrial devices. The three ‘C' shaped monopole radiating split rings, and open terminated tuning stub that protrudes from the O shaped strips to make up the proposed antenna configuration. This antenna consists of a circular patch of metal mounted above a ground plane, with a feed line connected to the center of the patch. The circular patch can be designed to resonate at multiple frequencies by adjusting its size and shape. By properly designing the feed mechanism and ground plane, the antenna can be made to produce circularly polarized radiation. Depending on the individual design and requirements, a multiband antenna may be able to cover anywhere between two and many more frequency bands. Frequency bands from 700 MHz to 1800 MHz and 1900 MHz–2600 MHz are used for mobile communication. The proposed Antenna aims to set the maximum length to half of the smallest feature size (e.g. assign a mesh operation in the slot with a maximum length of half the slot width). Convergence criteria are set and measured by the simulation setup, specifically in terms of the S-Parameters seen by the port. After an appropriate number of adaptive passes, and set the convergence criteria to delta S ≤ 0.01 (−40 dB).

The commercial frequency bands that the antenna can cover include terrestrial applications such as satellite communication, Television broadcasting, which is effective at switching between five distinct resonant frequency bands with centres at 7.224 GHz, 10.723 GHz, 13.808 GHz, 17.014 GHz, and 19.549 GHz across a variety of impedance bandwidth frequency spectrum spanning 74 MHz–192 MHz. The antenna presented in this paper has a wider bandwidth, improved radiation efficiency, and is appropriate for fixed mobile, satellite, and UWB (3.1–10.6 GHz) systems. The contributions are as follows.• The novel multi-band antenna is optimized simulated through Computer Simulation Technology Microwave Studio (CST-MS) software thereby achieving increased Gain and miniaturized structure

• A simple geometrical, low-profile and low cost antenna is proposed with radiating split ring structure.

• Parametric and comparative analysis are done for Gain, efficiency, Impedance bandwidth, operating frequency, VSWR and S11 parameters. Simulated results are verified with measured results

2 Proposed model

The proposed antenna is made up of FR-4 substrate with dimensions Ls = 50 mm and Ws = 50 mm, Hs = 1.6 mm. The substrate is 1.6 mm thick, and the ground plane of the antenna structure is the same size as the substrate. The metallization is 0.035 mm thick. The design of an antenna is shown in Fig. 1a as simulation and 1b as fabricated. The list of the optimized dimensions is given in Table 1. The radiator is made of a circular patch that receives power from a traditional microstrip feedline. There are four intermediary design steps for this antenna. Fig. 2 illustrates the C form ring r1, C shape ring r2, C shape ring r3, and circular patch radius r4. A standard microstrip line-fed circular patch with a partial ground plane is initially designed (see Table 2 [13]).Fig. 1 a–d Geometry design evolution of proposed antenna.

Fig. 1

Table 1 Optimized dimension.

Table 1Parameters	Dimension (mm)	
Length of the ground (L)	50	
Width of the ground (W)	50	
Inner radius of C shape ring (r3)	7	
Outer radius of circular patch (r4)	10	
Inner radius of C shape ring (r1)	1	
Outer radius of C shape ring (r2)	2	
Circular patch feed length (Lf)	23	

Table 2 Properties of FR4 [13].

Table 2Parameters	Values	
Relative permittivity (εr)	4.7	
Loss Tangent (tan δ)	0.0009	

Fig. 2 Design of antenna structure.

Fig. 2

To design the C form ring, the elliptical monopole is scaled down in the second phase by an iteration factor of 0.7. In the final phase, the substrate width is decreased without modifying the radiator or ground plane dimensions, miniaturizing the antenna footprint. The SMA connector is used to provide internal feed connection via the ground point. The gain of an antenna is given by the formula:(1) G=4π(ηA/λ2)

where G is the gain of the antenna, A is the effective aperture of the antenna, λ is the wavelength of the signal, and η is the radiation efficiency of the antenna.

For a multiband antenna, the effective aperture and radiation efficiency may vary across different frequency bands. Therefore, the gain of a multiband antenna can be calculated separately for each frequency band.

Radiation Efficiency The radiation efficiency of an antenna is given by the formula:(2) η=Prad/Pinput

where Prad is the radiated power and Pinput is the input power. For a multiband antenna, the radiated power and input power may vary across different frequency bands. Therefore, the radiation efficiency of a multiband antenna can be calculated separately for each frequency band. In the context of a multiband antenna, the impedance bandwidth refers to the range of frequencies over which the antenna can maintain a good match to a feed system at each of the desired operating frequency bands. The impedance bandwidth is typically expressed as a percentage of the center frequency of each band.

3 Experimental results and discussion

Multiband antenna is designed to operate on five distinct frequency bands. To analyze the performance of a multiband antenna, various parameters can be considered, including: Bandwidth, Return loss, Radiation pattern, Gain and VSWR.

For all resonance frequencies, it is discovered that the current is dispersed uniformly over the remaining area of the suggested antenna. The surface current is observed to be localized at the lower edge of the ground plane, inside the feed line, at the radiating edges, and in the middle of the first and second iteration radiating structures.

Fig. 3 shows the fabricated design of the proposed antenna. Here, a single microstrip-line fed with C type split rings with a fully ground size of 50 × 50 mm2 which is initially studied as per the evolution design,. S11 parameter has shown for the step-by-step evolution of an antenna and comparison results with C rings and without C rings are clearly represented in Fig. 4, Fig. 5. A parametric analysis is done step-by-step inclusion of the “C: split rings with micro strip line structure. It is evident from these analyses that increasing the number of SRR will shift the first or fundamental resonance to the higher frequency. Fig. 5 is the portrait of how the return loss is reduced when introducing C type split ring resonators. The comparison with C rings and without C rings is shown in above figure. At lower frequencies, the simulated and measured return loss can be observed to correspond rather well, but at higher frequencies, connector losses, ambient conditions, and soldering tolerances cause a little difference. Both the computed and observed data in Fig. 6 shows the resonance at each of the various operating frequency modes with roughly the same bandwidth. The performance of multi-band antennas that are made with FR4 substrate structures and operating in the five frequency range which are discussed in design.Fig. 3 Fabricated antenna structure.

Fig. 3

Fig. 4 S11(dB) Parameter simulated steps with C rings.

Fig. 4

Fig. 5 Return loss comparison with C rings and without C rings.

Fig. 5

Fig. 6 E-Plane and H-plane radiation pattern of lower frequencies.

Fig. 6

The summarized results are given for simulated design and measured of designed antenna. A larger impedance bandwidth is offered over the five different multi-band frequencies. The polarization in the all the distinct frequencies are validated with a considerably small difference between simulation and measurement. The addition of distinct "C" rings coupled to the partial ground in the radiating element, which enhances impedance matching and radiation characteristics on multiple bands is the major concern about the novelty of the work. The structure is optimized to get low return loss (−35 dB) for improving gain and efficiency.

The E-plane and H-Plane radiation pattern is typically plotted as a radiation intensity in decibels (dB) versus angle in the E-plane and H-Plane, with the antenna axis as the reference direction. The validated simulation results are compared with measured radiation pattern which is used to determine the directional properties of an antenna and it is shown at E-plane (h = 0) and at H-plane (h = 90) in Fig. 6, Fig. 7. The configurations for the distinct five frequencies 7.224 GHz, 10.723 GHz, 13.808 GHz, 17.014 GHz and 19.549 GHz and exhibited a virtually omnidirectional pattern in E-Plane and nearly dipole-like pattern in the H-Plane. At frequencies higher than 10 GHz, The patterns in both planes get distorted due to the higher modes of corresponding frequencies. The antenna emits an omnidirectional beam, as can be seen, which is advantageous for applications requiring broad coverage.Fig. 7 E-Plane and H-plane radiation pattern of higher frequencies.

Fig. 7

The measured antenna gain in operating frequency range of 7–21 GHz is 6.3 dB–8.1 dB. Fig. 8 plots gain pattern of the proposed antenna and is better at lower frequency in contrast to the higher frequency. It demonstrates that the proposed single antenna has a simulated gain of 6.5–8.4 dB and measured gain of 6.3–8.1 dB. Table 4 provides the comprehensive tabulation of simulated and experimental gain and efficiency.Fig. 8 Gain pattern of the proposed antenna.

Fig. 8

Table 3 Comparison of simulated and experimental results.

Table 3Operating Modes (GHz)	Simulated Operating frequency (GHz)	Experimental
Operating frequency (GHz)	Impedance Bandwidth (MHz)	Ratio
Bandwidth (MHz)	VSWR
Simulated	VSWR
Measured	S11
Simulated (dB)	S11
Measured (dB)	
f 1	7.21	8.8	136	144	1.8876	1.2643	−10.231	−18.23	
f 2	10.71	11.3	89	93	1.1676	1.2648	−22.23	−18.60	
f 3	13.80	14.25	74	76	1.0873	1.8780	−27.57	−15.82	
f4	17.01	15.34	123	134	1.1095	1.7083	−25.67	−11.66	
f 5	19.5	20	192	211	1.1052	1.7102	−32.81	−11.568	

Table 4 Multi-bands of proposed antenna.

Table 4Operating Bands (GHz)	Gain (dB)	Efficiency (%)	
Simulated	Measured	Simulated	Measured	
f1	7.3	7.1	82	79	
f2	6.5	6.7	78	76	
f3	7.3	7.0	82	80	
f4	8.4	8.1	84	82	
f5	7.0	6.8	79	77	

The supplied antenna has a resonance frequency of 10.723 GHz, a return loss of 18.60 dB, a bandwidth of 89 MHz in MODE 2, and a return loss of 15.82 dB in MODE 3. With a return loss of 11 dB, MODE 4 and MODE 5 operate at 17.014 GHz and 19.594 GHz, respectively. A maximum bandwidth of 192 MHz and minimum return loss of 18 dB are observed among the five different frequencies between 7.223 GHz and 19.594 GHz. Similarly, the maximum simulated efficiency is 82 % and maximum measured efficiency is 80 %. It is remarkable that the proposed antenna has gain above 8.4 dB and efficiency above 74 % throughout the operating bands.

Fig. 9, Fig. 10, Fig. 11 contrasts the antenna evolution phases according to their VSWR properties in simulation and measurement. As can be observed, the lower band's edge frequency is 2.9 GHz. The lower band edge frequency is shifted to 3.6 GHz together with the appearance of a new operating band with a frequency range of 7.2–20 GHz for the second band, and the lower band edge frequency is decreased to 4 GHz along with the merging of five operating bands with an iterative structure.Fig. 9 VSWR experimental setup.

Fig. 9

Fig. 10 VSWR measurement.

Fig. 10

Fig. 11 VSWR measurement (simulation).

Fig. 11

Table 3, Table 4, Table 5 depicts the conformability analysis of the proposed antenna with SRR. The proposed antenna is then compared with already proposed antennas with various features like substrate thickness, gain and return loss.Table 5 Comparison of proposed with other works.

Table 5Ref. No	Operating Bands (GHz)	Size (mm2)	Substrate Thickness(mm)	Gain (dB)	Return Loss (dB)	Efficiency (%)	Application	
[2]	3.4–3.9	32 × 33	1.6	5	−20	60	5G Smartphones	
[3]	8–12	34 × 34	1.7	20	NG	65.82	Multibeam Antenna	
[4]	0.95–4.49	80 × 90	1.2	4	−15	72	Wireless Technologies	
[9]	1.2–3.5	40 × 40	1.52	3.4	NG	68	Wireless Applications	
[10]	2.6–28	63 × 51	1.6	12.42	−10	75	Mobile Applications	
Designed	7–20	50 × 50	0.8	8.4	−35	82	Terrestrial Applications	
NG – Not Given.

Fig. 12, Fig. 13, Fig. 14 displays the proposed antenna's simulated and measured return loss. In the operational bandwidth, the antenna gain, however the gain is considerably diminishing outside of this band. The measured realized gain values of several samples do not differ by a significant amount. The antenna efficiency model when the antenna is curved ring inside the supporting structure, the percentage increases 84 % in this case. The impedance characteristics of the antenna are greatly altered when the antenna is constructed within the structure, a C type ring are widening the beam width and reducing return loss. Other similar antennas that have been reported also exhibit a similar phenomenon in Table 4. Gain, radiation pattern, and radiation efficiency are evaluated and remain constant in every mode of operation. Evaluation results are compared and presented in Table 3, Table 4, Table 5. The proposed antenna is compared to the cutting-edge antennas previously published for applications at 2.45 GHz–19 GHz. The data generally shows that the significance in the least in size, Operating bandwidth, low return loss in various mobile applications. Moreover, the proposed antenna compromises a improved average gain across both the bands with good radiation efficiencies thru the bands. Hence the antenna can become a suitable choice for Terrestrial applications such as Satellite-Based Navigation (GNSS) a satellite navigation systems employed frequencies at 7 GHz to give GPS receivers for timing data and precise locations, Radar Systems applications with 19.5 GHz radar systems can be used for a variety of purposes, such as weather radar, maritime radar, and military radar. For object detection and tracking and Remote Sensing applications with frequency band of 13.808 GHz band such as earth observation, monitoring soil moisture, vegetation health, and environmental conditions.Fig. 12 Return loss (measurement).

Fig. 12

Fig. 13 Return loss (simulation).

Fig. 13

Fig. 14 Return loss (measurement).

Fig. 14

In summary the proposed antenna has a novelty in terms of1. The incorporation of “C” type SRR enables the key performance parameters such as gain, radiation pattern and efficiency.

2. The incorporation of partial ground leads in isolation of antenna elements and mitigate surface wave propagation.

3. Low return loss (−35 dB) is achieved which increases efficiency of the multi-band antenna.

4. Furthermore, the antenna's adaptability and ease of integration into terrestrial communication devices are facilitated by its compact size and flat construction.

When compared with previous research work, the significance are as follows.1. Geometrical structure is simple with multi-band operation (5 modes) unlike [10].

2. The design cost and complexity is low and time to marketplace is fast enough unlike [11].

3. An additional ground plane is not required, C split ring structure for excitation of bands unlike [[12], [13], [14], [15]].

4. The FR4-based low-profile material utilized to achieve beset goals, which helped with cost reduction. The use of substrate is not expensive unlike [10].

4 Conclusion

The proposed antenna is fabricated with FR4 substrate based on multi-band frequencies. The effectiveness of SRR structured multi-band antenna is examined in this article. Using a C type split ring resonator increased the suggested antenna's performance parameter, resulting in gains and bandwidth increases of 26.6 % and 31.3 %, respectively. Also, in all five of its operational frequency bands, the C ring resonator displays a remarkable improvement in impedance matching situations. The proposed design has undergone fabrication and simulation, and the measured outcomes are generally consistent. A small and straightforward design of an ultra-thin patch antenna is put forth for the inbuilt antenna with 30 % more miniaturization than the traditional quadrilateral patch was achieved using patches. Designing a multi-band antenna is complex than a single-band antenna due to the need to accommodate multiple resonant frequencies and impedance matching requirements for each band. This complexity can increase design and manufacturing costs. But the suggested optimized antenna outperforms the existing antennas in terms of performance metrics.

Data availability statement

The experimental data used to support the findings of this study are included within the article.

CRediT authorship contribution statement

Porchelvi Natarajan: Writing – original draft, Methodology, Formal analysis, Data curation, Conceptualization. Titus Sigamani: Writing – review & editing, Supervision, Project administration, Methodology, Investigation.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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