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Meta-heuristic optimization algorithms have seen significant advancements due to their diverse applications in solving complex problems. However, no single algorithm can effectively solve all optimization challenges. The Naked Mole-Rat Algorithm (NMRA), inspired by the mating patterns of naked mole-rats, has shown promise but suffers from poor convergence accuracy and a tendency to get trapped in local optima. To address these limitations, this paper proposes an enhanced version of NMRA, called Salp Swarm and Seagull Optimization-based NMRA (SSNMRA), which integrates the search mechanisms of the Seagull Optimization Algorithm (SOA) and the Salp Swarm Algorithm (SSA). This hybrid approach improves the exploration capabilities and convergence performance of NMRA. The effectiveness of SSNMRA is validated through the CEC 2019 benchmark test suite and applied to various electromagnetic optimization problems. Experimental results demonstrate that SSNMRA outperforms existing state-of-the-art algorithms, offering superior optimization capability and enhanced convergence accuracy, making it a promising solution for complex antenna design and other electromagnetic applications.

This paper presents a design for temperature and pressure wireless sensors made of polymer-derived ceramics for extreme environment applications. The wireless sensors were designed and fabricated with conductive carbon paste on an 18.24 mm diameter with 2.4 mm thickness polymer-derived ceramic silicon carbon nitride (PDC-SiCN) disk substrate for the temperature sensor and an 18 × 18 × 2.6 mm silicon carbide ceramic substrate for the pressure sensor. In the experiment, a horn antenna interrogated the patch antenna sensor on a standard muffle furnace and a Shimadzu AGS-J universal test machine (UTM) at a wireless sensing distance of 0.5 m. The monotonic relationship between the dielectric constant of the ceramic substrate and ambient temperature is the fundamental principle for wireless temperature sensing. The temperature measurement has been demonstrated from 600 °C to 900 °C. The result closely matches the thermocouple measurement with a mean absolute difference of 2.63 °C. For the pressure sensor, the patch antenna was designed to resonate at 4.7 GHz at the no-loading case. The sensing mechanism is based on the piezo-dielectric property of the silicon carbon nitride. The developed temperature/pressure sensing system provides a feasible solution for wireless measurement for extreme environment applications.

A new antenna structure with broadband and high gain at the millimetre wave bands is presented. This antenna consists of a conventional patch fabricated on a thick low-temperature cofired ceramic (LTCC) substrate. By introducing an inner ground plane surrounding the main patch, the propagation of the surface wave is prevented, and antenna gain is increased. Furthermore, the bandwidth of this antenna becomes wider due to the coupling between the main patch resonator and the newly introduced dielectric resonator. The simulated results of the proposed antenna show a bandwidth and peak antenna gain at 60 GHz of 12 GHz and 9.4 dBi, respectively.

An efficient approach for designing directive patch antennas using metamaterials is presented. Based on the left-handed-material (LHM) transmission line model, circuit elements L and C of the LHM equivalent circuit model are computed in terms of the prescribed desirable characteristics of directive patch antennas. Formulae to calculate the LHM design parameters from the circuit elements L and C are developed. Design examples for the GSM900 and GSM1800 frequency bands in mobile communications are performed to illustrate validation and efficiency of this design approach.

This paper presents a novel microstrip patch antenna design using slots and parasitic strips to operate at the n77 (3.3–4.2 GHz)/n78 (3.3–3.8 GHz) band of sub-6 GHz and n96 (5.9–7.1 GHz) band of sub-7 GHz under 5G New Radio. The proposed antenna is simulated and fabricated using an FR-4 substrate with a relative permittivity of 4.3 and copper of 0.035 mm thickness for the ground and radiating planes. A conventional patch antenna with a slot is also designed and fabricated for comparison. A comprehensive analysis of both designs is carried out to prove the superiority of the proposed antenna over conventional dual-band patch antennas. The proposed antenna achieves a wider bandwidth of 160 MHz at 3.45 GHz and 220 MHz at 5.9 GHz, with gains of 3.83 dBi and 0.576 dBi, respectively, compared to the conventional patch antenna with gains of 2.83 dBi and 0.1 dBi at the two frequencies. Parametric studies are conducted to investigate the effect of the parasitic strip’s width and length on antenna performance. The results of this study have significant implications for the deployment of high-gain compact patch antennas for sub-6 GHz and sub-7 GHz 5G wireless communications and demonstrate the potential of the proposed design to enhance performance and efficiency in these frequency bands.

This paper presents a novel wearable textile array antenna designed to generate Orbital Angular Momentum (OAM) waves with mode + 1 at 3.5 GHz (3.4 to 3.6 GHz) of the sub-6 GHz 5G New Radio (NR) band. The proposed antenna is based on a uniform circular array (UCA) of four microstrip patch antennas on a felt textile substrate. Compared to previous works involving the use of hard substrates for OAM waves generation, this work explored the use of flexible textile substrates to generate OAM waves for the first time to the best of our knowledge. The overall dimension of the array antenna is 170 ×  156 mm 2 while the dimension of each element is 35 ×  35.7 mm 2 . In order to control the phase and generate OAM waves, the proposed antenna was designed using a felt textile substrate and meandering lines of various lengths connecting the radiating patches. 1.48λ was the separation between radiating patches in order to prevent mutual coupling between them. The antenna was fabricated and measured prior to comparison to simulations to validate this feature. It achieved a measured gain of 3.18 dBi with a bandwidth of 430 MHz (3.24 to 3.67 GHz). Additionally, mode purity analysis was carried out to verify the generation of OAM mode + 1, and the purity obtained was 52.12%. This paper also covered the effect of bending on OAM waves characteristics and the use of airgap technique to enhance the antenna gain. The antenna gain increased from 3.762 dBi to 5.327 dBi by using 1 mm airgap without affecting the mode purity. Furthermore, as per the Specific Absorption Rate (SAR) obtained, it is found that the proposed antenna is safe for on-body use. The novel approach in generating OAM using patch array antenna with flexible substrate by replacing conventional hard substrate has opened up new scope of research in wearable textile antenna domain. The proposed antenna has simple structure, easy to design, fabricate and deploy on human body and has important significance in scaling up this design to generate multiple OAM modes for carrying multiple signals simultaneously.

This paper presents a comprehensive review of symmetrically shaped antennas in terms of antenna size, dielectric materials, resonating band, peak gain, radiation pattern, simulating tools, and their applications. In this article, flower shape, leaf shape, tree shape, fan shape, Pi shape, butterfly shape, bat shape, wearable, multiband, monopole, and fractal antennas are discussed. Further, a survey of previously reported bandwidth enhancement techniques of microstrip patch antenna like introduction of thick and lower permittivity substrate, multilayer substrate, parasitic elements, slots and notches, shorting wall, shorting pin, defected ground structure, metamaterial-based split ring resonator structure, fractal geometry, and composite right-hand/left-handed transmission line approach is presented. The physics of these techniques has been discussed in detail which is supported by circuit theory model approach.

In this study, a novel technique to achieve multi-band performance for both reduced and conventional size circular microstrip patch antennas loaded with metamaterial has been proposed. Incorporation of symmetric slotting concept with the concept of additional mode modification for both MNG (µ negative) and ENG (ɛ negative) metamaterial loaded circular patch antennas have been shown. The use of metamaterial creates an unconventional mode, whereas symmetrical slotting not only modifies another band but also improves the gain by around 1 dB of unconventional mode for MNG loaded antenna. Design algorithms for metamaterial loaded circular patch antennas have been developed to achieve size reduction and highly directive multiband property. Based on these design algorithms, at first a reduced size triple band circular patch antenna loaded with MNG metamaterial has been shown where around 35% size reduction is achievable. Later, a triple band conventional size circular patch antenna partially loaded with ENG metamaterial has been designed with high gain and directive performances for all three bands compared to previously reported such antennas.

A compact dual-frequency ( 38 / 60   GHz ) microstrip patch antenna with novel design is proposed for 5G mobile handsets to combine complicated radiation mechanisms for dual-band operation. The proposed antenna is composed of two electromagnetically coupled patches. The first patch is directly fed by a microstrip line and is mainly responsible for radiation in the lower band ( 38   GHz ). The second patch is fed through both capacitive and inductive coupling to the first patch and is mainly responsible for radiation in the upper frequency band ( 60   GHz ). Numerical and experimental results show good performance regarding return loss, bandwidth, radiation patterns, radiation efficiency, and gain. The impedance matching bandwidths achieved in the 38   GHz and 60   GHz bands are about 2   GHz and 3.2   GHz , respectively. The minimum value of the return loss is − 42 dB for the 38   GHz band and − 47 for the 60   GHz band. Radiation patterns are omnidirectional with a balloon-like shape for both bands, which makes the proposed single antenna an excellent candidate for a multiple-input multiple-output (MIMO) system constructed from a number of properly allocated elements for 5G mobile communications with excellent diversity schemes. Numerical comparisons show that the proposed antenna is superior to other published designs.