International Journal

Specifications of the substrates are among the most important and problematic parameters that still do not have proper models in the design procedures of metasurfaces. In this paper, a new fast and exact algorithm based on artificial neural networks (ANNs) is presented, which makes it possible to design frequency-selective surfaces (FSSs) on various kinds of standard substrates. Also for the first

In this paper, an X-shaped fractal antenna with defected ground structure (DGS) is presented for multiband and wideband applications. The X shape is used due to its simple design and DGS is utilized to achieve size reduction with multiband and wideband features in the frequency range of 1?7 GHz. The proposed structure is fabricated on FR4 substrate with 1.6 mm thickness. We have proposed two diffe

In this paper, the structure of a common field-effect transistor (FET)-based negative impedance converter (NIC) that behaves as a negative capacitor is presented. The nonlinear modeling, analysis, and simulation of this non-Foster structure are presented in the time domain and the transient response of the circuit can be used to study the stability of the circuit. For the analysis of the circuit p

This paper presents the design of a size miniaturized and harmonic suppressed wideband double-section rat-race coupler (RRC). Series and shunt stepped-impedance transmission line units are proposed to replace the quarter wavelength transmission lines in the conventional design of wideband (50% fractional bandwidth) two-stage rat-race coupler. Design equations are derived using the lossless transmi

This paper presents an extension of the formulation of wave propagation in transverse electric (TE) and transverse magnetic (TM) modes in the case of metallic circular waveguides filled with anisotropic metamaterials. The determined higher-order modes have been analyzed and exploited to the design of filters. Among the particularities of anisotropic material, the backward waves can propagate below

Broadband transitions are presented in this paper for capacitively grounded coplanar waveguide to coupled microstrip (CMS) lines. These transitions are realized on both thick Rogers RO3003 substrate (thickness of 10 mils) and a thin benzocyclobutene (BCB) polymer film (thickness of 20 µm). A flat bandwidth of 4?20 GHz and 3.2 to over 40 GHz are measured for the RO3003 and BCB polymer substrates, r

In building highly efficient transmitters of today, one is forced to sacrifice linearity for efficiency. Some of the highest power amplifier efficiency figures are reported by envelope tracking (ET) amplifiers. These amplifiers can generate strong higher-order harmonics, which can lead to interference with receivers operating at the harmonic frequencies. Using non-linear interference cancellation,

A novel dual-band single-feed reconfigurable annular-ring slot antenna with polarization diversity is proposed. This antenna has the ability to switch frequency bands and polarization at the same time whereas applying a simple structure. It consists of two concentric circular slots and two tuning stubs on one side of the substrate and a 50 ? microstrip feed line and two stubs on the other side. Th