A new planar microstrip-fed monopole ultra-wideband (UWB) antenna with dual notched bands has been presented. By employing a simple dual-mode resonator with two symmetrical outer high-impedance lines beside the microstrip feed line of the proposed UWB antenna, two controllable rejection bands with high-frequency selectivity are created. The parametric studies of the proposed structure are explored

This paper proposes a novel wideband to concurrent tri-band frequency reconfigurable microstrip antenna. The frequency reconfiguration is achieved by using a pair of PIN diodes in the antenna feed line to switch the antenna either in wideband mode or in concurrent tri-band mode. In order to improve the bandwidth and gain of the antenna for wideband operation, the properties of J-K inverter and spl

In this paper, we propose a double balanced mixer with a tunable Marchand balun. The circuit is designed in a SiGe BiCMOS process using Schottky diodes. The tunability of the Marchand balun is used to enhance critical parameters for double balanced mixers. The local oscillator-IF isolation can be changed from ?51 to ?60.5 dB by tuning. Similarly, the IIP can be improved from 41.3 to 48.7 dBm at 11

This paper presents application of split ring resonators (SRR) in conventional waveguide slot array antenna to achieve performance improvement and multiband characteristics. Three SRRs have been placed on the transverse plane of a conventional slotted waveguide and has been simulated and measured. The measured results show that the antenna has dual band response with respective 10 dB return loss b

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