Asymmetric Coplanar Strip (ACS)-Fed with loop resonators is fashioned in the form of nested configuration, which imparts multiband radiation. By forming nested loops, it increases the number resonance substantially. An invented antenna possesses five rectangular loops, which induces the antenna to radiate 1.17 GHz, 1.74 GHz, 2.31 GHz, 2.93 GHz, 3.63 GHz and 5 GHz frequencies. The developed antenna is amalgamated by ACS-fed with loop resonators, it has been fabricated on a FR-4 substrate having the size of 18×18×1.6 mm3, εr= 4.4 and tanδ = 0.02. To ascertain the optimal peak gain of the antenna, Frequency Selective Surface (FSS) amelioration approach has been carried out. It is fashioned on 44.5×44.5×0.8 mm3 FR-4 substrate by 4×4 FSS array configurations. At 5 GHz resonance, the antenna imparts the peak gain of 0.52 dBi without FSS. To meliorate the peak gain, the antenna is covered by 4×4 FSS array, which executes as the reflector for rendering the peak gain of 6.62 dBi. The transmission line model of FSS unit cell has been explored with the help of LC values to identity the band reject mechanisms, which is examined by Agilent ADS software. The calibrated radiation factors of the fabricated antenna with FSS cover endorse simulated counterparts, which is suitable for GSM, WiMAX and WLAN applications.

A straightforward planar nonagon-shaped Terahertz (THz) Metamaterial Absorber (MMA) is devised and simulated for refractive index sensing applications. The proposed absorber employs three layers, with a polyimide dielectric substrate sandwiched between two copper layers, avoiding the need for multiple layers or numerous resonators in a single unit cell. The output absorption curves of this MMA exhibit polarization dependency, resonating at three frequencies in the x-direction and two frequencies in the y-direction, resulting in a total of five resonant frequencies across both directions. In the x-direction, the absorption rates at resonance frequencies of 0.78 THz, 0.793 THz, and 0.81 THz are 96.5%, 99.7%, and 99.8%, respectively. In the y-direction, the absorption rates are 99% for resonance frequencies of 0.791 THz and 0.799 THz. The refractive index (RI) sensing mechanism is analysed by placing a 1 mu m analyte over the top patch structure, revealing a high quality factor and figure of merit (FOM) values of 371 and 47.6 RIU-1, respectively. The physical mechanisms of the structure are investigated through electric field distribution, magnetic field distribution, and surface current distribution plots. Additionally, the polarization and incident angle characteristics of the structure are assessed by varying the angle values from zero degrees to ninety degrees. This absorber is intended for utilization in terahertz sensing applications.

In this work, a compact substrate integrated waveguide (SIW) antenna, both the T and C shapes are inverted and loaded with slots is designed for triple band operations. This antenna has been improved by impacting slots into a rectangular cavity to achieve tri-band radiation. An inset microstrip feedline regulates the internal rectangular cavity, inverted C-shaped slots and reverted T-shaped slots of the designed antenna. The proposed antenna incorporates with size of length, width, thickness 30 × 30 × 1.6 mm3, that has been integrated on a lowcost Flame Retardant-4 dielectric substrate. It exhibits enhanced performance in terms of radiation characteristics and peak efficiency. The characteristics of return loss S11(dB)and current surface distribution have been studied through simulation and verified . Reflection coefficient, gain, and the radiation patterns of the E and H planes are illustrations for antenna parameters.

The proposed work aims to understand the effect of dimension variations in a CPW-fed SRR metamaterial antenna for sub- 6 GHz applications in 5G communication. The resonant frequency behaviour is analyzed over 1 to 7 GHz, utilizing an ANN to model the intricate relationship between antenna dimensions and resonance properties using MATLAB R2021a. Traditional antenna design methods are usually based on analytical equations, empirical formulas, and manual optimization methods. While these approaches have achieved commendable results, they are inadequate in meeting the inherent complexity of today's communication requirements. The intelligence of deep learning methods research aims to shape an era of antenna design where precision and performance converge through the transformative powers of artificial neural networks.

A multiband half-mode substrate integrated waveguide (HMSIW) slotted antenna is developed for ISM/WiMAX/WLAN applications. HMSIW technique has been utilized to acquire antenna compactness. Two inverted L-shaped slots of half wavelength are embedded onto a HMSIW rectangular cavity for attaining a hybrid mode (i.e., Half-mode of TE110+ Half-mode of TE120), which induces a lower resonance at 2.4 GHz. An inverted L-shaped slot is influenced to radiate hybrid mode at 2.4 GHz, while the innermost inverted L-shaped slot radiates modified TE110 mode at 3.30 GHz. A multiband is obtained by amalgamation of hybrid mode (at 2.4 GHz), modified TE110 mode (at 3.30 GHz) and modified TE120 mode (at 5.38 GHz). The radiating modes are elucidated by using mode theory methodology for ascertaining the resonance characteristics of the prototype antenna. The antenna parameters have been optimized by artificial neural network technique using MATLAB. The antenna geometry possesses a shrinkage size of 30 x 16 x 1.6 mm(3), which has been designed on FR-4 substrate. To vindicate the simulated consequence, the fabricated prototype has been tested. It contributes the fractional bandwidth of 6.4% (2.09-2.23 GHz) in the hybrid mode at 2.18 GHz, 9.03% (2.89-3.17 GHz) in the half cavity mode TE110 at 3.10 GHz and 9.96% (5.11-5.65 GHz) in the half cavity mode TE120 at 5.42 GHz, respectively, which is beneficial for ISM, WiMAX and WLAN band wireless applications.

A miniaturized asymmetric coplanar strip fed with meander lines is developed for hexaband wireless applications. Multiband with compact size of the antenna is developed by using meander lines. The designed antenna is enhanced by an increased number of meander lines. The invented antenna is composed of three meander lines, it yields the antenna to excite 1.13, 2.35, 2.91, 3.46, 3.96, and 4.5 GHz, respectively. The prototype antenna is fed by ACS, which is printed on a 14 x 24 x 1.6 mm(3) FR-4 substrate and dielectric constant of epsilon(r) = 4.4. MATLAB tool is utilized in the ANN computation to amend the physical values of the antenna. The calibrated and simulated radiation attributes are identical with each other. The designed antenna provides distinguishing characteristics such as good reflection coefficient, impedance matching, and size miniaturization. It imparts empirical peak gains of 0.028 dBi at 1.14 GHz, 1.305 dBi at 2.35 GHz, 1.54 dBi at 2.86 GHz, 1.79 dBi at 3.43 GHz, 2.43 dBi at 3.96 GHz, and 2.58 dBi at 4.5 GHz, which is suitable for GSM/WLAN/WiMAX and C-band wireless applications.

An electrically small multiband planar antenna is presented by using rectangular split ring resonator (RSRR) metamaterial element for LTE, WiMAX and WLAN applications. The designed antenna possesses asymmetric coplanar strip (ACS)-fed Hilbert Curve Fractal Antenna (HCFA) loaded with RSRR metamaterial for multiband radiation at 1.44 GHz, 3.76 GHz and 5.27 GHz. ACS-fed HCFA is responsible for creating the first (at 1.44 GHz) and second (at 3.76 GHz) resonance frequencies owing to the coupling between ACS-fed HCFA and ground plane. Moreover, the RSRR yields upper resonance at 5.27 GHz owing to the metamaterial transmission line. The stop band and pass band nature of the RSRR and its negative permeability characteristics are described using an effective medium theory. An equivalent circuit model of the proposed antenna is investigated with the help of Agilent ADS to validate the operating frequencies. Also, the geometrical parameters have been optimized using the artificial neural network (ANN), which is performed by MATLAB. The proposed antenna has been fabricated on a 18 × 16.5 × 1.6 mm3 FR-4 dielectric having _r = 4.4 and tan = 0.02. It provides multiband response at 1.4 GHz, 4.4 GHz and 5.3 GHz with a − 10 dB impedance bandwidth of 330 MHz, 570 MHz, and 340 MHz, respectively, which is usable for LTE, WiMAX and WLAN band applications.

The Half-mode Substrate Integrated Waveguide (HMSIW) has accumulated vast attentiveness since it was launched. This is vitally due to the afforded benefit of size reduction in contrast to a Full mode SIW and mainly to the availability of vent in the fundamental configuration. In this article, a semi-mode Substrate Integrated Waveguide (SIW) antenna is proposed for multi-band applications. This antenna is built by loading an inverted ‘L’ slot, a rectangular slot and a square slot with a small metallic incision on a rectangular SIW cavity for multiple band radiation. The introduction of slots generates a hybrid mode as a combination of TE110 and TE120 modes by coupling of these modes through metallic vias. This in turn radiate an inferior resonant frequency. The constructed half-mode SIW antenna gives in multiband response due to resonant slots and influence of microstrip inset feed thus restoring the gain and radiation characteristics of full SIW.

A dual-band substrate integrated waveguide (SIW) cavity backed antenna loaded with complementary split ring resonator (CSRR) metamaterial is proposed for WiMAX/WLAN band applications. This antenna uses a rectangular cavity and CSRR slots on the ground plane for dual band radiation. The rectangular SIW cavity resonator produces two cavity modes TE_110 and TE_120 into free space owing to array of metallic vias. By introducing CSRR, it excites the lower hybrid modes for realizing a low-profile antenna design at 2.5 GHz due to strong coupling effect in the SIW cavity resonator. The mode theory mechanism is utilized for analysis the designed antenna. The geometry of the fabricated antenna is developed on a low cost FR-4 dielectric substrate with dimensions 30 × 30 × 1.6 mm3 to resonance at 2.5 GHz and 5.4 GHz. The experimental S_11 (dB) exhibits a fractional bandwidth of 4 S_11 (dB), planar configuration and unidirectional radiation patterns.

A slotted cavity-backed Substrate Integrated Waveguide (SIW) antenna is suggested for use in wireless applications. The SIW cavity-backed antenna that is being proposed is designed for multiband operations. The operational frequencies for UMTS, WLAN, C-band and wave applications are 2.15 GHz, 2.7 GHz, 4.2 GHz, and 6.8 GHz respectively. Two typical modes are provided by a rectangular cavity (i.e., TE110 and TE120). The SIW cavity's current distribution is altered by loading slots on top of the cavity. The traditional modes couple together without enlarging the antenna and provide a new resonance frequency (i.e. Hybrid mode). As a result, the proposed antenna can operate in several bands, and the mode theory method has been used to explore radiating modes.

In this article, an asymmetrical coplanar strip (ACS) fed for dual band radiation is used to construct a new tiny printed antenna with dimensions of 21.57× 25.62× 1.6 mm3 on FR4 substrate. The Proposed antenna consists of a ground plane, monopole, and loop resonator that are fed via the ACS Technique. The radiating element has centre frequencies of 1.23 GHz and 2.73 GHz, respectively, with a -10 dB impedance bandwidth of 1180 MHz (1.18-1.26 GHz) and 2550 MHz (2.55-2.94 GHz). For achieving antenna size reduction, ACS-fed applied with monopole provides topmost resonant frequency at 2.73 GHz and loop resonator generates bottom resonant frequency at 1.23GHz. A prototype antenna has a considerable radiation pattern and is suited to the Global Positioning System (GPS) and Wireless Local Area Network (WLAN).

A concise patch antenna with three frequency bands is presented. The design of the antenna utilizes Open Complementary Split Ring Resonators (OCSRRs) and aims to provide various wireless communication applications such as Worldwide Interoperability Microwave Access, Wireless Local Area Network (WLAN) and C-band frequencies. The utilization of a patch antenna with a partial ground plane proves suitable for the coverage of WLAN (2.67GHz-5.47GHz) frequencies. In order to attain resonance at both WiMAX (3.43GHz) and C-band (4.18GHz) frequencies, an OCSRR is incorporated into the design of the patch antenna. To attain effective impedance matching and enable multiband operation, the circular patch antenna incorporates OCSRRs. The dimensions of the antenna measure $\mathbf{23}\times \mathbf{23}\times\mathbf{1.6}\ \mathbf{mm}^{\mathbf{3}}$ , encompassing an overall size that allows for Omni-directional coverage across all three frequency bands. The prototype of antenna is designed and simulated using HFSS. The results are being validated through a parametric study of OCSRR. The bidirectional pattern is acquired when observing the plane at $\mathbf{\Phi}=\mathbf{90}$ degree, while the azimuthal plane corresponds to obtaining an omnidirectional radiation pattern. The proposed antenna possesses several beneficial characteristics, such as its compact dimensions, ability to operate across multiple frequency bands, and efficient impedance matching.

Asymmetric coplanar strip(ACS)-fed with Hilbert curve fractal antenna is proposed for multiband wireless application. ACS-fed can be used to act as quarter wave transformer for impedance matching. Hilbert curve fractal antenna is used to achieve low frequency resonant, which is capable for antenna miniaturization. The proposed antenna yields multiband at 1.3080 GHz, 2.2880 GHz, 3.1350 GHz and GHz, which is suitable for LTE, Wi-Max and WLAN applications. The desired radiation characteristics is acquired in both E-plane and H-plane radiation patterns. The frequency response of the proposed antenna has been verified by an equivalent circuit analysis, which is assessed by ADS software. The optimized dimensions of the antenna have been obtained by ANN using MATLAB.

The substrate-integrated waveguide is an emerging competitor for realizing microwave and millimeter-wave ranges. This article illustrates a novel design of a multiband antenna loaded with a slot by using a Substrate Integrated Waveguide (SIW) technique of 21x 27 mm dimensions for performing multiband operation. For the antenna's radiation, a pair of rectangular complementary split-ring resonators are used in the proposed design. These slots apply to exciting tight space hybrid modes present in SIW for significantly improving the antenna performance. The proposed antenna is implemented by using a printed circuit board (PCB) technology. A pair of complementary rectangular beam splitting slits are used in the proposed work to improve the antenna performance. As a result, the proposed antenna operates at 2.61 GHz, 2.82GHz, 4.465GHz, 5.76GHz, and 6.6GHz, covering S-Band and C-Band applications. Proper radiation characteristics have been confirmed by the HFSS electromagnetic tool.

A miniaturized cavity-backed antenna loaded with slots is designed using substrate integrated waveguide (SIW) technique for ISM/WiMAX/C-band/RFID applications. This antenna has been developed by embedding slots onto a hexagonal cavity for quad band radiation. The proposed antenna possesses hexagonal cavity, inverted U-shaped slot and innermost inverted U-shaped slot, which are governed by an inset microstrip feedline. The hexagonal SIW cavity-backed antenna offers cavity modes TM110$$ {\mathrm{TM}}_{110} $$ at 4.16 GHz and TM210$$ {\mathrm{TM}}_{210} $$ at 5.8 GHz. Two inverted U-shaped slots are introduced on the top metallic surface of the cavity to drive the lower resonant modes for acquiring antenna miniaturization. These lower resonance frequencies are formed by hybrid mode (i.e. TM110+TM210$$ {\mathrm{TM}}_{110}+{\mathrm{TM}}_{210} $$) at 2.4 GHz and coupling of hybrid mode (i.e. TM110 + hybrid mode + TM210) at 3.33 GHz. The ANN optimization method has been performed to enhance the performance of the antenna using MATLAB. The designed antenna has a compact size of 25 x 25 x 1.6 mm(3), which is fabricated on a low cost FR-4 substrate having epsilon r=4.4$$ {\varepsilon}_{\mathrm{r}}=4.4 $$ and tan delta=0.002$$ \tan \delta =0.002 $$. To validate the simulated equivalence, the fabricated antenna has been measured. It yields a fractional bandwidth of 5.04% (2.31-2.43 GHz) in the hybrid mode at 2.38 GHz, 6% (3.22-3.42 GHz) in the coupling of hybrid mode at 3.33 GHz, 19.19% (3.97-4.78 GHz) in the cavity mode TM110$$ {\mathrm{TM}}_{110} $$ at 4.22 GHz and 7.2% (5.69-6.11 GHz) in the cavity mode TM210$$ {\mathrm{TM}}_{210} $$ at 5.8 GHz with stable radiation pattern.

A compact asymmetric coplanar strip (ACS)-fed with Hilbert Curve Fractal Antenna (HCFA) is proposed for GSM (1.8 GHz), WiMAX (3.3 GHz) and WLAN (5.5 GHz) applications. The proposed antenna occupies a compact size of 18 × 16.5 × 1.6 mm3 involving ACS feed line with HCFA and ground plane. A low cost FR-4 epoxy is used as a substrate material having a dielectric constant of $$\left( {\upvarepsilon_{\text{r}} } \right)$$ 4.4. HCFA consists of line sectors governed in a predictable fractal order, thus it is capable of constructing multiband and shrinkage of antenna size. MATLAB program is utilized to confirm the number of fractal order. By incorporating a suitable fractal order of HCFA, it is efficient to cover a lower resonance frequency of 1.8 GHz for attaining 90% of compactness. Experimental and simulated data are examined. The proposed antenna yields a dipole pattern in the xz plane (elevation plane) and omnidirectional pattern in the yz plane (azimuthal plane).

A low-profile substrate integrated waveguide (SIW) cavity-backed antenna loaded with slots is presented for multiband operations. This antenna is designed by loading a rectangular and square-shaped slot onto a rectangular SIW cavity for multiband radiation. The slots are created inside the rectangular cavity to induce a hybrid mode (i.e. $${\text{TE}}_{110} + {\text{TE}}_{120}$$ ), which supports to radiate a lower resonance frequency. The rectangular slot is used to excite $${\text{TE}}_{120}$$ mode at 5.21 GHz, while square-shaped slot excites hybrid mode at 2.21 GHz. This hybrid mode is obtained by coupling the cavity modes $${\text{TE}}_{110}$$ and $${\text{TE}}_{120}$$ through the metallized via-holes. The designed antenna yields multiband response owing to resonant slots when governed by the inset microstrip feedline. The operating modes are explained with the help of mode theory mechanism. The fabricated antenna comprises with dimensions 30 $$\times$$ 30 $$\times$$ 1.6 mm3, which is printed on a low-cost Flame Retardant-4 dielectric substrate. To verify the simulated counterparts, the fabricated antenna has been tested, which offers a fractional bandwidth of 6.9% (2.10–2.25 GHz) in the hybrid mode at 2.18 GHz, 8.4% (3.35–3.64 GHz) in the $${\text{TE}}_{110}$$ mode at 3.45 GHz and 10.8% (5.04–5.61 GHz) in the $${\text{TE}}_{120}$$ mode at 5.26 GHz with suitable far-field pattern.

A miniaturized coplanar waveguide (CPW) fed rectangular nested loop antenna is proposed for penta band wireless applications. Multiband and antenna compactness are obtained by using rectangular loop resonators. The proposed antenna has been optimized by increasing the number of loop iterations. The designed antenna comprises four rectangular loops, it constructs the antenna to excite 1.01 GHz, 1.67 GHz, 2.30 GHz, 2.92 GHz and 3.48 GHz frequency bands. The fabricated geometry has a dimension of 30 x 30 x 1.6 mm(3), which is developed on a low-cost Flame Retardant-4 substrate having epsilon(r) = 4.4 and tan delta = 0.02. The resonance behavior of the proposed antenna is verified by employing LC quasi-static design equations. The measured reflection coefficient and far-field pattern are exhibited to support the performance of the designed antenna for wireless applications.

This article describes a compact split ring monopole antenna loaded with a Hexagonal Split Ring Resonator (Hex-SRR) for Wireless Local Area Network (WLAN) and Radio frequency Identification (RFID) applications. The resonance frequency of the proposed antenna is obtained by making use of a split ring structure and a metamaterial element Hex-SRR. The prototype antenna is printed on an FR-4 substrate having a dielectric constant (epsilon(r)) of 4.4 with dimensions of 21x21x1.6mm(3). The split in the ring radiating element is used to achieve good impedance matching, and the Hex-SRR creates a new resonance frequency of 5.8 GHz. This paper includes equivalent circuit investigation, operating mechanism, and band characteristics of Hex-SRR as well as negative permeability details. The fabricated antenna provides an impedance bandwidth of 1180 MHz (5.23-6.41 GHz), which is suitable for WLAN and RFID applications. Good similarity is inferred between the simulated and measured results of the proposed antenna.

The multiband operation is intended for WiMAX and WLAN application by using a cpw-fed meander line monopole antenna. The antenna structure contains an FR4 substrate with dimensions of 20 × 20 × 1.6mm 3 . A prototype antenna involves a ground plane and a cpw fed meander line monopole antenna to achieve multiband resonant frequencies. The radiating portion is used to cover the corresponding impedance matching of -10 dB . The multiband features of metamaterial-promoted meander line structure along with negative permeability (µ) properties are discussed in detail. The designed antenna will have a radiation configuration of Omnidirectional (H-plane) and dipole direction (E- plane). The multiband resonant frequencies are evaluated by using EM Software HFSS version 13.