Nader Komjani

Learn More
In this letter, a new compact ultra wideband circular monopole antenna with an acceptable band-rejection characteristic is investigated. This rejection band is created by means of an electromagnetic band-gap (EBG) structure. The EBG structure that is used here is a mushroom-like structure. An equivalent circuit model is employed to investigate the stopband(More)
A novel broadband unit cell is proposed in this letter. This new cell element consists of three coupled circular rings where four quasi-spiral delay lines are connected to the outer ring to provide the required phase shift. The spiral shape of the delay lines exhibits more than 1000 <sup>&#x00B0;</sup> of phase swing. The cross-polarization level of the(More)
This paper presents an optimum design method based on the Method of Least Squares (MLS) for the traveling-wave substrate integrated waveguide (SIW) slot array antenna. Elliot's design formulas for dielectric filled waveguide including external and internal mutual coupling are used for the design by means of the equivalent waveguide. In order to achieve an(More)
This paper presents a novel tunable terahertz antenna based on a hybrid graphene-metal structure fed by a waveguide. First, the hybrid plasmonic waveguide is studied by analytical and numerical methods. Then, an efficient terahertz antenna is designed by an analytical approach using the transmission line model. The antenna performances are evaluated in the(More)
In this letter, we present a patch antenna over a high impedance surface (HIS) substrate, using Jerusalem cross-shaped frequency selective surfaces (JC-FSSs). The objective in this design is to obtain the enhancement in bandwidth (BW) while achieving the symmetric radiation pattern over the frequency band of interest. In order to derive optimal dimensions(More)
In this paper, we present a novel approach for improving the bandwidth of a microstrip patch antenna using Jerusalem crossshaped frequency selective surfaces (JC-FSSs) as an artificial magnetic ground plane. The invasive weed optimization (IWO) algorithm is employed to derive optimal dimensions of the patch antenna and JC-FSS element in order for the whole(More)
This letter presents a scheme to generate circularly polarized waves in a reflectarray antenna. It originates with the design of a linearly polarized element, consisting of an aperture coupled patch with slot and line of variable length. Using this prototype, a circularly polarized element is then designed. The method used here is based on the finite(More)
This study presents the propagation properties of plasmonic slab waveguides based on graphene compared with noble metals. Transfer matrix theory as an analytical method and finite-element method as a numerical approach are applied for analysis of one-dimensional plasmonic structures. Calculating the guided mode propagation constants of the waveguides,(More)
Novel double layer Substrate Integrated Waveguide (SIW) technology is used for realization of conventional H-Plane filter which is manufactured in waveguide. This proposed filter is totally realized in doubl layer dielectric substrate with metallic vias and fabricated using a standard printed circuit board(PCB) process. In previous works, prototypes of E(More)
Abstract—In this paper the simulation of ultra wideband microstrip antenna is considered. Because of the ultra wideband characteristics of this antenna, it is better to use time domain simulation methods. In this work we use three dimensional transmission line matrix method (3D-TLM) and EPML-TLM algorithm for modeling PML boundary condition directly applied(More)