Analytical Modelling of Trapezoidal Monopole Structured Antenna for Wi-Fi, Industrial Scientific and Medical, and Wireless Communication System Applications ^†

Abstract

A dual-band monopole antenna of a trapezoidal shape is modelled and the analytical study is presented in this article. The designed model is working between 2.5 and 3 GHz by producing bandwidth value of 500 MHz and 4–5 GHz with a bandwidth value of 1000 MHz. The designed antenna polarization is linear, and the radiation is non-directive. The performance bandwidth is 4:1, 2:1, and 5:1 at 2.5, 2.6, and 4.5 GHz and the gain value is 2.3 dB, 2.9 dB, and 5.1 dB, respectively. An impedance value of 50 ohms is observed at the port during the analysis. The analysed model is best suitable for the wireless communication applications of ISM, Wi-Fi, and WLAN, with moderate gain and efficiency. In wireless communication systems, effective and adaptable antennas are in high demand. This work proposes an analytical modelling technique for a trapezoidal-structured monopole antenna for Wi-Fi, ISM, and other wireless communication systems. The proposed antenna has a compact size, broad frequency coverage, and omnidirectional radiation patterns. The analytical model considers the antenna’s geometric characteristics, material qualities, and operating frequencies using electromagnetics laws. Through rigorous mathematical definitions, the study reveals the antenna’s resistance, radiation efficiency, and gain patterns across the necessary frequency bands. Furthermore, this analytical model predicts antenna performance without time-consuming simulation or costly prototypes. A thorough analysis assesses the trapezoidal monopole antenna’s suitability for Wi-Fi, ISM, and wireless communication applications, addressing their individual requirements and limit. The bandwidth, gain, radiation efficiency, and impedance matching are examined to show the antenna’s capacity to fulfil modern wireless system needs.

1. Introduction

The never-ending demand for compact and multiband antennas in the telecommunication system motivates and invokes researchers to design advanced models. Simple-structure monopole antennas for commercial communication applications need to be designed at a low cost. Researchers have designed several antenna models for multiband applications which serve the GSM—Global System for Mobile Communication, GPS—Global Positioning System, UMTS—Universal Mobile Telecommunications System, PCS—provincial civil services exam, Bluetooth, Wi-Fi—Wireless Fidelity, LTE—Long-Term Evolution, and wireless LAN—Local area network, etc. The never-ending demand for wireless communication applications-based antennas and microwave devices has ruled the wireless field with their advanced features like high bandwidth, gain, and efficiency with low loss.

A coplanar waveguide-fed trapezoidal monopole antenna designed to operate between 3 and 4 GHz is developed in [1]. The radiating structure in the monopole antenna is etched with a U-slot to develop the notch band antenna. The provided antenna consists of a dielectric permittivity value of 2.2 and tan delta value of 0.009 and is fabricated on Rogers product of RT-duroid-5880 substrate material. The notch band antenna’s overall dimensions are approximately 51 × 45 × 1.6 mm. To achieve multiband functioning, a small slotted printed monopole antenna with metamaterial loading is proposed [2]. This antenna configuration shows multiband characteristics and was first inspired by the idea of refractive index value-based metamaterial structure transmission lines. The antenna (permittivity = 6.15, Rogers RT/duroid 6006, loss tangent = 0.0019) resembles a V-shaped design with the integration of the radiating patch on the upper portion and the ground structure on the bottom portion to the dielectric material. Satellite military communication band (7.25 to 8.4 GHz) and long-distance communication system (4 to 8 GHz) applications are both well justified by the suggested antenna’s modelling results.

A compact-sized wideband Coplanar excited dipole antenna is designed for wireless commercial communication system applications in [3]. The suggested antenna has a very compact design and is placed on an RT-Duroid substrate with a 1.6 mm thickness. The antenna, providing monopole structures like radiation properties, has good antenna gain throughout its operating bands, making it suitable for integration into portable electronics for wireless device communication. A portable dual-operative band antenna with frequency reconfigurability for WLAN—Wireless Local Area Network/IEEE- Institute of Electrical and Electronics Engineers-802.11n applications is designed in [4]. Slots included in the radiation patch are used to achieve the resonant modes, and switching PIN diodes is used to achieve band tuning. Switching diodes coupled between slot gaps allows for variations during the first and next resonant frequencies. The switching capabilities of the diodes are best used to notch specified frequency bands and select the operation frequencies. The main characteristics of this unique antenna include low cross polarization, a consistent radiation pattern, and an average gain value of 2.8 dB. To obtain frequency-based notch band characteristics in a whole wideband, a flexible circular monopole of a conformal nature antenna with a splitring-based resonator is designed in [5]. The frequency band notching characteristics because of the microstrip line feeding are produced by splitring resonators positioned at one side of the substrate and the complementary splitring resonators at another side of the substrate at a defective ground plane [6]. A portable frequency reconfigurable antenna for ISM wireless communication systems applications is proposed in [7]. The 58 mm × 48 mm antenna design model is made on FR4 epoxy with a dielectric permittivity value applied of 4.4 and a thickness of 0.8 mm. The designed antenna includes of a ground plane with a defective T-shape that serves as a reflector. BAR 64-02V PIN diodes are employed as switching components in the modelling of the frequency-based reconfigurable design antenna, and the antenna is loaded via a microstrip conductive transmission line [8].

A frequency-tuneable monopole circular antenna with notch band properties is designed and analysed in [9]. To achieve the appropriate band rejection, the diameters of the slots are precisely adjusted and optimised. To achieve evolution in the notch bands, two PIN diodes are attached between the stubs and feedline [10]. The switching between the diodes controls the radiating structure’s length and internally influences the antenna’s reconfigurable behaviour. The projected antenna is originally designed to notch the 3.1–3.7 GHz and 5.1–5.8 GHz WiMAX—Worldwide Inter-operability for Microwave Access and WLAN operating bands [11]. A unique fractal-shaped antenna is designed on transparent material in [12]. The analysed antenna shall be used for vehicle communication applications since it is adaptable and conformal to the surface of automobiles. The articulated antenna model uses a polyvinyl chloride substrate material with a loss tangent of 0.02 and εr = 3 with an overall size of 55 × 40 × 3 mm.

The properties of a CPW-fed printed dual-notch monopole antenna are presented in [13]. By including a second H-shaped slot structure in the radiating element, a dual notch band is made possible. At 3.5 GHz for WiMAX & 8.3 GHz for military/radar communication, notch bands were obtained. A unique structure proposed by combining a rectangular monopole and parasitic patch elements results in a small, three-notch band monopole antenna [14]. A 50 ohm impedance feed line is perfectly matched with a corner twisted-type rectangular radiating structure on the upper side and to the defective ground surface. The designed antenna has triple broad notch band characteristics between the WLAN band at 4–6 GHz, the satellite communication band at 7.6–9.8 GHz, and the 10.5–11.5 GHz band [15]. A unique heart symbol-shaped electrically compact antenna attached to a planar AMC—artificial magnetic conductor on an FSS–frequency selection surface for use in WLAN (i.e., 5.8 GHz) and WiMAX (i.e., 3.5 GHz) applications is designed in [16]. The overall dimension of 0.63 λ0 × 0.63 λ0 × 0.33 λ0 is surrounded by a heart structure-shaped closed resonator ring (HCRR-HIGH-CAPACITY RADIO RELAY) as a shunt inductor. The designed model is supported by a model artificial magnetic conductor (AMC), and a distinct reflection of −900 to +900 has been seen in the AMC structure’s reflection phase [17].

A triple-band notching property ultra-wideband antenna is designed with a CSRR—complementary splitresonator and a patch with an inverted T-structure stub [18]. In the UWB—Ultra-wide band, it emits a constant dipole pattern like radiation in the E-plane and an omnidirectional pattern observed in the H-plane. Combining a DGP—defective ground plane, inverted T-structure stub, and CSRR generates triple-notch bands with characteristic frequencies at 4.4 GHz (for RFID—Radio-Frequency Identification applications), 6.8 GHz, i.e., RFID, and 9.2 GHz, i.e., radar system application purposes, respectively. A highly effective multi-broadband resonance tree-shaped fractal antenna is proposed in [19]. The partial portion etched ground structure is altered by inserting a narrow slotted rectangular-shaped slot, and the recommended circular-shaped patch element is modelled by incorporating slots in similar to a tree-shaped fractal antenna structure. The developed antenna is made from an FR4 dielectric substrate of dimensions 40 × 25.05 × 1.6 mm³. The designed antenna operates in four different bands with 10 dB impedance bandwidths of 600 MHz (2.2 to 2.8 GHz), 1070 MHz (3.3 to 4.37) GHz, 2550 MHz (4.75 to 7.3 GHz), and 2200 MHz (9.7 to 11.9) GHz, according to the measurement results. A hexa-band antenna with a special structure for LTE, Bluetooth, and Wi-Max devices is proposed in [20].

Four PIN diode switch-based frequency-configurable dual operating band antennas were designed for LTE 2500 band and WiMAX applications. The fabricated/prototyped antenna works in the relevant LTE band and WiMAX frequency bands (2.5–2.69 GHz and 3.4–3.6 GHz). The designed antenna emits both unidirectional and bidirectional radiation at higher frequency bands [21]. A non-symmetric electromagnetic structured band gap antenna (EBG—Electronic Bank Guarantee) has been designed for wireless communication applications. By including an EBG structure in the antenna, the gain is increased from 2.8 dB reading to 13.9 dB, and a parametric analysis is carried out to optimise the antenna performance characteristics, with an efficiency higher than 82.5%.

1.1. Needs of ISM, WI-FI, and Wireless Lan Applications

ISM, Wi-Fi, and wireless LAN communication systems use bandwidth values of 0.5 GHz (500 MHz) and 1 GHz (1000 MHz). Following these systems’ demands and restrictions, these values match:

1.1.1. Industrial–Scientific–Medical Bands

In the 2.4 GHz ISM band, ISM applications require 0.5 GHz bandwidth. For unauthorised industrial, scientific, and medical use, ISM bands are internationally designated. Other bands are 902–928 MHz and 2.4–2.4835 GHz. For Bluetooth and Zigbee, the 2.4 GHz spectrum is crucial. For scientific research and industrial automation, the 1 GHz bandwidth meets several ISM applications that need greater spectrum. High-frequency applications can use 5.8 GHz ISM channels with 1.7 GHz bandwidth.

1.1.2. Wi-Fi

Both 0.5 GHz and 1 GHz Wi-Fi bandwidths matter. Wi-Fi runs across the 2.4 GHz and 5 GHz frequency bands, featuring 0.5 GHz and 1 GHz bandwidth, respectively, and 802.11b/g/n Wi-Fi uses the 2.4 GHz band’s 0.5 GHz bandwidth. Indoor use and wall penetration are possible. For 802.11a/n/ac Wi-Fi, the 5 GHz band has 1 GHz bandwidth. High-capacity and high-performance Wi-Fi networks benefit from its more channels, lower interference, and higher data speeds.

1.1.3. Wireless LAN Connection

The 0.5 GHz and 1 GHz bandwidths allow wireless LANs, including Wi-Fi networks, to use a variety of frequencies for varied deployment scenarios. The 0.5 GHz bandwidth makes indoor coverage and less data-intensive applications possible. In busy places like offices and public spaces, the 5 GHz band’s 1 GHz bandwidth provides more channels and less interference for high-density deployments.

2. Antenna Modelling

A trapezoidal monopole has been designed on the substrate material FR4 with dimensions of 31 × 42 × 1.6 mm. Coplanar wave guide feeding has been used with an impedance of 50 ohms in the current design.

Complex antenna design, modelling, and analysis can be difficult. Engineers and researchers face these issues and use various methods to overcome them. There are common issues and possible solutions: Designing antennas for certain frequency ranges or bandwidths can limit broad-frequency coverage. To overcome frequency restrictions, multi-band or reconfigurable antennas might be constructed. These antennas can operate at many frequencies or dynamically modify their resonance frequency. Small form factors can make it difficult to build effective antennas, especially at lower frequencies. As a solution, meandered structures or metamaterials can minimise antenna size without compromising performance. Designing antennas with complicated shapes can be computationally intensive and difficult to precisely model. As a solution, advanced numerical methods like FEA or MoM can simulate antenna performances with complex geometry.

2.1. The E and H Planes

A study of the antenna’s radiation patterns in the E- (Elevation) and H- (Azimuthal) planes shows how its design affects its ability to send out signals in all directions. In the E-Plane (Elevation), the vertical radiator and ground plane make a mirror picture, which promotes even radiation in the vertical plane. In the H-Plane (Azimuthal), symmetry and the ground plane equally send radiation in all directions, creating an omni-directional pattern. The way these parts are put together in the antenna design makes for efficient, even radiation, which is perfect for applications that need coverage in all directions, like wireless communication systems and broadcasting.

2.2. Trade-Offs and Design Considerations

Optimizing antenna performance with modest gain and efficiency requires trade-offs and design considerations. Trade-offs: Size: High-gain antennas are larger and may not fit in small areas. Moderate gain balances performance and size for the antenna. Efficiency vs. Complexity: Complex antenna designs increase production costs. Choosing moderate efficiency simplifies the design and cuts production costs. Considerations: Design Wi-Fi routers use moderate-gain antennas for wide-area coverage. The signal range and directionality are well balanced or battery-powered devices, and antennas with high gain may use too much power. Energy-efficient moderate-gain antennas are available. Interference: Neighbouring devices and reflections can affect high-gain antennas. Moderate-gain antennas reduce interference and perform well. Optimising antenna performances with modest gain and efficiency requires trade-offs and design considerations. Trade-offs: Size: High-gain antennas are larger and may not fit in small areas. Moderate gain balances performance and size for the antenna.

2.3. Efficiency

Efficiency in antenna design determines how well an antenna converts electrical energy into electromagnetic waves. It measures the antenna’s signal reception efficiency. High-efficiency antennas convert a large portion of electrical energy into electromagnetic waves, improving transmission and reception. Efficiency is measured as a percentage by dividing radiated (or received) power by input power. A higher efficiency means more input power is radiated or captured, while a lower efficiency means more energy is lost as heat or other methods. High-efficiency antennas have many benefits: Increased Signal Quality: Efficient antennas boost signal power, improving signal quality, coverage, and communication reliability. High-efficiency antennas reduce signal loss and transmit signals farther due to less power lost to heat or inefficiency. Energy Efficiency: Efficient antennas reduce signal transmission and reception power in wireless communication devices, extending battery life. However, antenna efficiency is sometimes difficult to design and manufacture: High-efficiency antennas may need intricate radiating elements and feeding mechanisms to reduce losses. Precision Manufacturing: To ensure efficiency, manufacturing must meet strict tolerances and employ high-quality materials, which increases production costs. Antenna efficiency varies with frequency, making it difficult to maintain high efficiency across a large range of working frequencies.

2.4. FR4 Substrate Material and Impact on the Antenna’s Performance

The antenna performance depends on the substrate material. FR4, which is inexpensive and electrically conductive, is a popular substrate material. Antenna designs must include specifics regarding the FR4 substrate material’s dielectric characteristics, thickness, and performance. 1. Dielectric Properties: Highly dielectric FR4 fiberglass-reinforced epoxy laminate. Typically, the antenna’s dielectric constant (εr) ranges from 4.4 to 4.7 and is vital for its electrical properties. The antenna’s effective electrical length and impedance matching are affected by a greater dielectric constant’s substrate wavelength reduction. The dielectric constant of the FR4 material employed is crucial for antenna construction and analysis. 2. Thicker FR4 substrates affect the antenna’s radiation pattern, impedance, and bandwidth. Thicker substrates increase mechanical strength but may impair antenna effectiveness. Thinner substrates can enable smaller designs but may limit power and bandwidth. Specifying the FR4 substrate’s thickness is critical for understanding how it affects the antenna’s electrical properties. The choice of FR4 substrate material affects antenna performance, including gain, radiation pattern, bandwidth, and impedance matching. Engineers and researchers can better evaluate the antenna’s trade-offs and optimise its design to satisfy performance objectives by giving substrate material information. A thinner FR4 substrate may be better for compact designs but require careful impedance matching, whereas a thicker substrate may be better for high-power applications but narrower bandwidth.

The antenna dimensional view and side view is presented in Figure 1a–c. The dimension values are in mm and are showcased in

Table 1. Dimensional characteristics.

Name	Description	Value
Le	Monopole Element Length	15.76 mm
we	Monopole element Width	15.76 mm
α	Taper angle at monopole base	35.64 θ
Sf	Feed gap	64.53 um
Wg	Ground Width	31.52 mm
Lg	Ground Length	25.21 mm
H	Substrate Height	975.6 um

. The antenna basic parameters like reflection coefficient, impedance, VSWR, and smith chart representation are presented in Figure 2.

2.5. Reflections or Obstructions

The performance of antennas can be drastically impacted by environmental conditions and surrounding objects. Signal reflections and obstacles are just two problems that can be caused by these external factors. Radio waves can be reflected by nearby surfaces, including water, air, and solid things like buildings and automobiles. Multipath propagation and signal attenuation due to interference introduced by reflections are possible outcomes. It is possible to reduce the effects of reflections through careful antenna siting and design, such as the use of beamforming techniques. Signal attenuation and decreased range can occur when an antenna’s line of sight to its intended target is blocked by, for example, trees, buildings, or terrain. Obstructions can be reduced with careful site planning that takes into account the antenna’s height and direction. If you want your antenna to work well and reliably under real-world settings, you need to take into account its surroundings and eliminate any potential interference.

2.6. Antenna’s Performance and Enhancing Wireless Communication Devices’ Functionality

When it comes to improving the functionality of wireless communication devices in real life, the performance qualities of an antenna are of the utmost importance. These features have a direct effect on how well the gadget can send and receive signals. Here is more about how important they are: Pattern of Radiation: The pattern of radiation shows how an antenna sends or receives electromagnetic waves in different directions. A well-made antenna with a controlled radiation pattern makes sure that messages go where they are needed, giving the best coverage and the least amount of interference. In real life, this means better signal strength, fewer dead spots, and better use of the radio spectrum. Gain is a measure of how well an antenna directs energy in a certain way. Higher gain antennas can increase the range of communication, which makes them useful in places where coverage over a long distance is important, like in rural or remote areas. Bandwidth: The range of bands that an antenna can work well at is determined by its bandwidth. With a wide bandwidth, the antenna can handle a wider range of messages, making it useful in situations where different applications or services use different frequency bands. Polarisation: Aligning the polarisation of an antenna is essential for receiving and sending signals. Making sure that the antenna’s polarisation matches that of the signal source or target improves signal strength and reduces signal loss due to polarisation mismatch.

2.7. Antenna’s Performance with Other Existing Antennas

Comparative Antenna Performance Analysis: Assessing the performance of a new antenna for a certain communication band against existing antennas for the same frequency range is crucial and essential to development. The comparative analysis serves numerous important purposes: Performance benchmarking: Engineers can benchmark the antenna’s performance by comparing its properties to existing designs. This benchmarking identifies strengths and flaws. The new antenna’s competitive benefits must be highlighted. Whether it has higher gain, wider bandwidth, reduced sidelobes, or improved efficiency, these benefits must be quantified and described. Comparisons to current antennas can reveal areas for improvement in the new design. It is important to iteratively improve antenna parameters and performance. Market positioning requires knowing how the new antenna compares to competitors for commercial purposes. Improving the antenna design can boost sales. In terms of application, the antenna’s performance is context dependent. Compared to realistic antennas, the antenna’s real-world applicability is assessed to ensure it fits consumers’ needs. If regulatory standards require particular performance criteria, the produced antenna must be compared against compliant antennas to assure compliance. Engineering often compares antenna performance using gain, bandwidth, directivity, efficiency, radiation pattern, impedance matching, and environmental durability. The antenna’s response to interference and multipath propagation may also be assessed.

2.8. Antenna’s Efficiency Percentages

A basic antenna efficiency calculation compares radiated or received power to input power. The antenna efficiency formula is Radiated Power/Input Power × 100% = Efficiency (%). An antenna is 80% efficient if it radiates 80% of its input power. Performance and energy usage depend on antenna efficiency in real-world applications: Signal Quality: High-efficiency antennas broadcast and receive signals more efficiently, improving signal quality, range, and communication reliability. Low power consumption makes efficient antennas appropriate for battery-operated systems. They save electricity and battery life. Cost-effectiveness: High-efficiency antennas maximise input power utility, eliminating the need for extra amplification or signal processing equipment. Efficiency percentages show how successfully the antenna transforms electrical energy into electromagnetic waves and can help design applications.

3. Results and Analysis

The refection coefficient parameter shows the antenna operating band (<−10 dB) is from 2.5 to 3 GHz and exhibits bandwidth values of 500 MHz and 4–5 GHz with a bandwidth value of 1000 MHz. Figure 3 shows the Reflection coefficient (dB) in the graph and the image of display. Figure 4 shows the impedance characteristic values of the antenna in real and imaginary mode with close to fifty ohms impedance value at operating bands.

Figure 5 shows the antenna’s three-dimensional characteristics at three different operating frequencies. The antenna gain at 2.5, 2.6, and 4.5 GHz shows 2.3, 2.9, and 5.1 dB omni directional, directive, and butterfly-like, respectively. The normalized gain in 2D, polar, and 3D is presented in Figure 6 for 2.5 GHz. The same parameters are analysed and presented in Figure 7 for 2.6 and 4.5 GHz, respectively.

The above Figure 6a,b dashed lines represents idle radiation and tick lines denotes real time radiation from proposed model. Figure 7a,b dashed lines represents idle gain and Figure 7b denotes real time gain from proposed model.

3.1. Implications of the Peak Realized Gain Values

Peak gain values like 2.3, 2.9, and 5.1 dB affect signal power and coverage area, making them important antenna parameters. These values are crucial for antenna gain novices: Short signal strength: dB: Logarithmic gain levels are expressed in decibels. Comparing antennas, a higher dB gain indicates stronger signal in a certain direction. Each 3 dB increase doubles the power. A reference antenna has a moderate signal strength boost compared to an antenna with a peak realised gain of 2.3 dB. For moderate signal amplification, it can be useful. The signal is amplified significantly at 2.9 dB. Signal strength must transcend mild obstacles or distances with it. The peak realised gain of a 5.1 dB antenna amplifies signals well. Long-distance communication and difficult signal propagation conditions suit it.

3.2. Trapezoidal Shape for the Monopole Antenna Design

A trapezoidal monopole antenna has a wide bandwidth, which is one of its main benefits. Broadband antenna designs are better for lower wireless communication applications with low frequency ranges. 1. Shape: As wireless communication uses many frequency bands, the trapezoidal shape provides multiple resonance frequencies and reduces frequency sensitivity, enabling broadband performance. 2. Compactness: Smaller wireless communication applications may use antennas built into portable devices, IoT sensors, or small communication equipment. Ideal for such applications, the trapezoidal shape allows a relatively compact antenna design. Tapering from a wide base to a small top reduces footprint while retaining radiating qualities. 3. Enhanced Radiation Characteristics: The trapezoidal shape helps boost monopole antenna radiation. From the broader base to the smaller top, this form gradually tapers, reducing backlobe radiation and increasing forward gain. For antenna directivity and radiation pattern management applications, like minimising interference or improving coverage in a certain direction, this feature is useful. 4. Mechanical Stability: Lower wireless communication applications may result in antenna vibrations and impacts. Trapezoids are more mechanically stable than vertical monopoles. More structural support from its larger base reduces external pressures from bending or deforming it.

The simulated results obtained from the FDTD—Finite-Difference Time-Domain analysis match with the measured readings of the prototyped antenna shown in Figure 6. The designed antenna is tested in the anechoic chamber, and the antenna measurement setup and obtained efficient results for the placement of the proposed antenna in practical scenarios in the desired band of applications are shown in Figure 7.

4. Conclusions

A compact trapezoidal monopole antenna on an FR4 substrate to execute functionality in the lower wireless communication system applications is narrated in this work. The designed antenna is more suitable for commercial communication applications of ISM, Wi-Fi, and wireless LAN with bandwidth values of 0.5 GHz and 1 GHz at dual bands. The radiation at these operating bands provide monopole-like and omni pattern-shaped directional orientation in the E- and H-plane, respectively. The peak realized gains at three frequencies are 2.3, 2.9, and 5.1 dB with an efficiency of 72% 78%, and 83%, respectively. The developed antenna shows excellent performance characteristics exhibited in the wireless device’s operated communication bands with considerable bandwidth and moderate gain and efficiency.