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In this paper, we propose a novel stacked circular microstrip antenna (C-MSA) fed by a CPW. The planar EBG structure is used to obtain broadband performance for dual operating frequencies. The bandwidth of 6.73 % and 7.55 % are obtained for the low- and high-frequency bands, respectively. Moreover, broadside radiation patterns and gains of about 8.0 dBi in average are also obtained over the both bandwidths...
An HIS with nonidentical lattices and its reflection properties are investigated and discussed. Using a linear reflection phase gradient from pi/2 to pi/2 with pi10 step with unit cell index across face, the surface can steer a reflected beam to 20.2deg in thetas. The pattern of the electromagnetic field reflected with the normally incident y-polarized wave is analyzed and experimented.
In this paper a new equivalent circuit for the EBG structure which represent the feature of surface-wave suppression is proposed. The equivalent circuit of the EBG unit cell consists of capacitors, inductors and transmission lines of series branches, as well as a capacitor and an inductor of shunt branch. These equivalent circuit parameters are based on physical implementations of EBG structures....
In this paper, we presented several applications of millimetrewave EBG structures with controlled defects, fabricated using a rapid prototyping technique based on extrusion freeforming. Numerical simulations were performed for the design of millimetrewave woodpile structures. The fabricated woodpile structures have been measured and showed a good agreement with the simulated results. A directive millimetrewave...
In this paper, we take up mushroom type EBG structures and clarify the frequency-band-rejection characteristics of the finite EBG structures on the finite ground plane, and we also compare that with the infinite EBG structures and the semi-infinite EBG structures. Here, we analyze the reflection characteristics of a normal incidence plane wave.
EBG (electromagnetic bandgap) structures have lately attracted considerable attention both for the surface wave reduction and low profile antennas. One of the most remarkable features of EBG structures is their periodicity. Brillouin pointed out the bandgap phenomena by the periodic structure early in the 20th century. Indeed, the surface wave reduction by EBG structures is explained in the same way...
In recent years, the metamaterials and its applications to antenna and other fields have been widely investigated theoretically and experimentally. The metamaterials are usually realized by some periodic structures composed of a conductor and/or dielectric/magnetic materials. In order to design the characteristics of metamaterial properly, some theoretical and/or numerical techniques are required...
This paper presents a new improved enhanced effective medium method that can be used to evaluate performance of the HIS structure with different patch shapes. This method is a combination of the enhanced effective medium method and the Guass' law. To validate the proposed method, the surface impedance values of the circular patch HIS structure obtained from both HFSS simulation tool and the presented...
In this paper, a dual-band circularly polarized antenna is designed for the UHF band (860 MHz ~ 960 MHz) and ISM band (2.4 GHz ~ 2.48 GHz) RFID reader applications and novel microstrip patch RFID tag antennas for the UHF RFID band (908 MHz -914 MHz) in Korea are proposed. They have less sensitive characteristic against the size of metallic object, wide impedance bandwidth and a long reading distance.
The reflectarray is the type of antenna that includes a feed similar to that used in a conventional curved reflector antenna but its reflector is planar and formed by an array of reflecting elements. These elements use a suitable phasing mechanism to beam an incident wave, as launched by the feed, in a desired direction. Recent years have seen a considerable interest in microstrip reflectarrays. One...
In this paper, we adopted the EBG structure for the antenna substrate to achieve low profile antennas. The thin mushroom-like EBG substrates with narrow gaps were fabricated to limit the area size of the substrate to apply small equipments. The impedance and radiation pattern of a dipole antenna were measured when the antenna was closely located above the EBG substrate. It was confirmed that a dipole...
The power of undesired electromagnetic radiation from some wireless communication terminals such as a handy-phone and a personal computer tends to raise its level and to extend a frequency range. These terminals are composed of some printed circuit boards PCBs which contains many low-power LSIs, so that the immunity to the electromagnetic wave tends to fragile, and is some possibility of operating...
From this paper, the characteristic of the rectangular ring EBG structure has been presented. The band gap characteristic for EBG structure is depending on the gap between the elements and the different via location between elements in EBG structure. The operating frequency of this EBG structure can be used for ISM band application.
In this paper, a wideband EBG structure with an enhanced bandgap and homogeneity by loading lumped-elements is presented. Lumped-element capacitors are loaded between the adjacent patch conductors, and also lumped-element inductors are loaded in series with vertical vias in the proposed EBG, leading to a drastic reduction of the unit cell size, and consequently, an enhanced homogeneity. In addition,...
In this paper, we report our experimental and numerical results, confirming the phenomenon of dual in-phase reflection, i.e. dual-resonant behavior, for a TM-polarization plane wave oblique incidence on the conventional mushroom-like EBG structures. A modified local resonance cavity (MLRCC) model of EBG structures has been presented to explain the essential features of dual- resonant behavior and...
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