In this paper, a slotted conical patch connected to a small triangular patch multiband antenna for both microwave and millimeter-wave applications is presented. The designed antenna has three characteristics. The proposed antenna is a multiband, having a compact size of 0.35λ0 × 0.35λ0 × 0.004λ0 at its lowest operational frequency, i.e., 2.4 GHz, and more importantly, it can cover both the microwave and millimeter-wave bands with a single feeding. According to the −10 dB matching bandwidth, experimental results show that the antenna operates at (2.450–2.495) GHz, (5.0–6.3) GHz, and (23–28) GHz. The reduced size, simple design, and multiband large bandwidth are some of the advantages over the reported designs in the latest literature. Both simulated and experimental results show a good agreement, and the proposed antenna can be used for wireless local area network (WLAN) applications and fifth-generation (5G) wireless communication devices.

In this research work, a wideband metamaterial-inspired circularly polarized antenna array is designed. The designed antenna array has a low radar cross-section (RCS) but high gain. The basic element of the planar array is analyzed as a dual-band electromagnetic absorber. Under normal incidence, the designed basic element has two absorbing peaks at 3.6 and 11.2 GHz. Further, four elements of the 4 × 4 elements array are connected to the feeding network through metallic vias. The feeding network is designed on the bottom layer. The circular polarization is archived by feeding the cross shape metallic resonator at two feed points, in a manner that there is a 90 time phase difference between the fields of two. It is shown that a good axial ratio is obtained over a wideband. This design method simultaneously validates high gain antenna performance and also meets the conditions of low-RCS.

A simple, low‐cost and compact antenna is presented for ultra‐wideband applications. The proposed antenna design has improved characteristics as compared to the available different designs reported in the recent literature. The antenna is designed on FR4 substrate with microstrip feed line. Better results are obtained by optimising the geometrical parameters of patch and the lengths of ground and strip line. According to the criteria of −10 dB matching bandwidth, the designed antenna covers a high bandwidth ranging from 3.1 to 16 GHz. It was identified that the voltage to standing wave ratio is less than 2 which is also the desired characteristic for matching of an efficient antenna. The maximum dimension of this antenna is smaller than 0.27λ0 at the lowest frequency of operation, where λ0 is the free space wavelength. Further, low‐cost, smaller size and simple design of the proposed antenna makes it very suitable for biomedical applications.

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In this paper, a metasurface (MS)-based multi-functional electromagnetic (EM) structure is proposed to realize its two different applications, namely absorption and radiation. The proposed structure is based on periodic arrays of disk-shaped metallic patches and split rings with four embedded lumped resistors. The metallic vias are inserted from top to bottom to connect the disk-shaped patches with a feeding network designed on the bottom layer where two p-i-n switches are embedded in the feeding network to alter the different functions of the proposed structure. For free space incident plan wave, the designed structure works as an absorber when the p-i-n switches are switched OFF. The absorber operates over a frequency band from 6.2 GHz to 8.2 GHz and unchanged over an incident angle from 0° to 30° for both TE and TM polarized incident waves. The same structure also works as a low scattering and high gain radiator when the p-i-n switches are turned ON and radiate within absorbing frequency band, i.e. from 7.5 to 8.0 GHz. The designed structure is fabricated and experimentally verified for EM absorption and radiation applications.

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