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 paper, a bi-layered ultra-thin multifunctional chiral metasurface is proposed to obtain asymmetric transmission (AT), cross-polarization conversion (CPC), and circular dichroism (CD). The multifunctional chiral metasurface realizes an AT with more than 70% efficiency over a Ku-band frequency range from 14.3 to 15.8 GHz, while in the operating frequency band from 13.5 to 16.2 GHz, the CPC ratio is above 90%. In addition, the metasurface exhibits CD in the K-band with a CD parameter of 0.6 at 24 GHz. Furthermore, the functionalities of AT and CPC are stable with changes in the incident angle of up to 60° for both transverse-electric and transverse-magnetic electromagnetic waves. For verification of the anticipated concept, the proposed chiral metasurface is fabricated and measured. The proposed design can be used for potential applications in the Ku- and K-bands for satellite communication and radar.

In this paper, we propose a periodic structure that is capable of alternating between absorption and radiation mode. The designed periodic structure consists of an array of 6×6 square shaped unit cell. Each unit cell consists of a multi-layered structure, with dimensions of 0.5λ×0.5λ. The resonators are placed on the top layer and the feeding network is designed and implemented on the bottom layer. The ground layer is sandwiched between the two dielectric substrates. All resonators are connected to a 50Ω feed-line using the corporate feeding technique. To achieve broadband absorption, lumped resistors are inserted into the resonators. The proposed metasurface structure achieves broadband radiation, with low RCS and high gain, in the propagation direction whereas broadband absorption is achieved, when it is exposed to a free space plane wave. Moreover, the metamaterial absorber has stable absorptivity for an incident angle of (00-300). To verify the in-band absorption and radiation of the proposed design, a 6×6 periodic array of resonators has been fabricated and experimentally verified in an anechoic chamber. The measured results validate the performed simulations.