A compact Hexa-band Bio-inspired antenna is presented in this paper. The structure of the proposed antenna is realized from a semi-Vine-leaf shape, Defected Ground Structure (DGS) and arc-slots techniques. The total dimension of the antenna is 0.35λd x 0.14λd; where λd is the guided wavelength at low frequency (2.37GHz). The design begins with a semi- Vitis vinifera leaf-shaped radiating patch monopole structure, fed with an asymmetric microstrip feedline to achieve compactness. Five (5) arc slits are then introduced on the radiating patch of the initiator with an intention to create band notches and thereby results in multiband and further miniaturization. The proposed antenna is analyzed, simulated and fabricated. The measurement results of the proposed antenna show that the antenna operates at 2.37GHz, 3.06GHz, 3.52GHz, 4.28GHz, 4.88GHz, and 6.0GHz with a -10dB fractional bandwidth of 11.97%, 4.61%, 12.43%, 6.77%, 2.46%, and 11.55% respectively. The peak gain of the proposed antenna is 3.21 dBi. The radiation patterns of the proposed antenna are Bi-directional at XZ-plane and XY-plane, but Omnidirectional at YZ-plane. Owing to the compactness of the antenna, suitable radiation pattern, acceptable gain and high radiation efficiency, the proposed antenna is suitable for several applications such as Industrial, Scientific and Medical (ISM) Band, Radar, WiMAX, 5G mid-band, Bluetooth, WLAN, WiMAX, LTE, and Wi-Fi. The contributions of this work are: (i) the use of asymmetric microstrip feedline for miniaturization purpose contrary to the commonly used asymmetric coplanar strip; (ii) simple formulation for the predictions of notch bands introduced by the slit on the radiating patch; and (iii) presentation of ultra-compact hexa-band antenna compared to the existing multiband antenna.

The evolution of advancement in communication technologies and ever-increasing demand by users for compact communication devices has necessitated a shift in the design approach to achieve antenna structures that are compact and robust. Owing to the diverse communication requirements, antenna systems operating across wide bands have become a necessity. An antenna that is capable of working effectively in several bands is called wideband antenna. In this work, a bio-inspired microstrip antenna (Bi-MPA) for wideband application is proposed and simulated. The radiating patch of the proposed Bi-MPA is the shape of Carica Papaya leaf. The structure was realized through the perturbation of the circular shape patch. The proposed antenna has an impedance bandwidth of 4.3 GHz (1.9 GHz–6.2 GHz) at a return loss of 10 dB while it exhibits a narrow band at 7.2 GHz (6.99–7.44 GHz) and 9.3 GHz (9.15–9.35 GHz) bands. The gain of the proposed antenna is between 2.60 dB and 10.22 dB and the radiation pattern is quasi-omnidirectional. The proposed Bi-MPA is compact and suitable for global system for mobile communication (GSM1900), Universal Mobile Telecommunication System (UMTS), Wireless Local Area Network (WLAN), Long Term Evolution (LTE2300 and LTE2600), Worldwide Interoperability for Microwave Access (WiMAX), C-band, X-band, and sub6 GHz fifth-generation (5G) band. Our contribution to the scientific community in this work is that we have proposed a single antenna structure that is suitable for communication in all the bands mentioned in order to ensure compactness in the mobile devices as compared to base station antennas.

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A comparative analysis of compact multiband bio-inspired Asymmetric microstrip fed antennas (BioAs-MPAs) is presented in this paper for the first time. The proposed antennas are based on semi-Carica papaya-leaf shaped, semi-Monstera deliciosa-leaf shaped, semi-Vitis vinifera shaped, Defected Ground Structure (DGS) and L-slit techniques. The antennas are built on a 33 × 15 mm2 Rogers duroid 5880 substrate. The modelling equations for resonant frequencies of the proposed arbitrarily shaped radiating patch is based on modified circular patch modelling equations. The semi-Carica papaya-leaf antenna operates at 2.4 GHz and 4.4 GHz, Monstera deliciosa-leaf antenna operates at 2.6 GHz, 4.4 GHz and 5.5 GHz, while Vine-leaf antenna operates at 2.5 GHz and 5.4 GHz. The proposed BioAs-MPAs antennas radiation patterns at E-plane are Bi-directional in all the operating frequencies with suitable X-Pol purity and have Omnidirectional radiation patterns at H-Plane in all the operating frequencies. As a result of the analysis, it was found that each of the bio-inspired structures has its unique merit over the others. Owing to the small size, stable radiation pattern, acceptable gain and high radiation efficiency, the proposed BioAs-MPAs antennas are suitable for ISM band, Bluetooth, Wi-Fi, WiMAX, LTE, UMTS, Sub6 GHz 5 G band, ZigBee and RF-Altimeter used in unmanned aerial vehicle and Aviation industry.

A compact bio‐inspired electromagnetic bandgap integrated wearable antenna (Bio‐EBG‐iwA) is proposed in this work. The Bio‐EBG‐iwA is based on the hybridization of semi‐Vitis vinifera leaf‐shaped patch, asymmetric feedline, reflected G‐shaped slot, partial ground, and a stub on the ground plane. The antenna is built on the locally made textile material called Aso‐oke (Alari) with permittivity and a loss tangent of 1.43 and 0.019, respectively. The dimension of the proposed antenna is 0.20.25emλg×0.10.25emλg×0.00890.25emλg (22 mm × 12 mm × 0.7 mm) at 2.45 GHz. Despite its compactness, the gain of −0.48 and 2.5 dBi are achieved at 2.45 and 5.7 GHz respectively without electromagnetic bandgap (EBG). A dual‐band textile‐based uniplanar compact electromagnetic bandgap (UC‐EBG) is introduced to create isolation between the human tissue and the antenna. The dual‐band UC‐EBG is realized through the use of a modified slitted‐square ring (MSSR) and the 90° rotated H‐shaped patch on Aso‐oke (Alari) with a thickness of 2.1 mm. The periodicity of the proposed UC‐EBG is 34.5 mm. The antenna is placed on a 2 × 2 array of the proposed UC‐EBG separated by a 3 mm foam thickness. The radiation efficiency of 88.97% and 79.85% are achieved at 2.45 and 5.7 GHz respectively. The gain of the proposed UC‐EBG integrated antenna increased from −0.48 and 2.5 dBi to 5.9 and 10.7 dBi at 2.45 and 5.7 GHz, respectively. The front‐to‐back ratio (FBR) of 26.3 dB is achieved with the use of UC‐EBG. The use of UC‐EBG results in a 98.31% and 99.4% reduction in average SAR at 2.45 and 5.7 GHz, respectively. The off‐body and on‐body performance analysis of the proposed UC‐EBG integrated antenna show that the proposed EBG integrated antenna (Bio‐EBG‐iwA) is a suitable candidate for wearable application. To the best of our knowledge, this is the most compact wearable antenna with suitable gain, radiation efficiency, and high FBR. In addition, our proposed UC‐EBG shows that slitting is an effective way of miniaturizing the EBG structure.

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A new compact ultrawideband (UWB) bioinspired antenna is presented in this work. The proposed antenna consists of a vine leaf (Vitis vinifera) shape as the radiating patch, defected ground structure (DGS), and a vertical rectangular slot (VRS) on the ground plane. The vine leaf shape is realized from a circular patch (initiator) in this work. The proposed antenna is built on an FR4 substrate with a dielectric constant of 4.4, a loss tangent of 0.02, and a thickness of 1.5 mm. The total dimension of the proposed bioinspired antenna is 35 × 27.6 mm2. The proposed antenna has a fractional bandwidth of 115.43% (3.7 GHz–13.8 GHz) at 10 dB return loss, a radiation efficiency between 78% and 97%, a peak gain of 6.7 dB, and a stable radiation pattern. The contributions of this work to the existing literature are as follows: (i) the investigation of a vine leaf shape for UWB antenna application; (ii) the adaptation of the conventional monopole patch antenna design equation to determine the lower edge frequency (LEF) of an arbitrary shape monopole antenna; (iii) the presentation of a compact UWB antenna with high fractional bandwidth compared with recent works in the literature, and (iv) the use of FR4 substrate to achieve a peak radiation efficiency of 97% with a compact structure.

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