In this paper a low cost, high gain, low cross-polar and compact edge feed printed elliptical antenna with a partial ground plane and parasitic patches is proposed and investigated. The proposed antenna is fabricated on a 1.6mm thick FR4 substrate with dielectric constant of 4.4 and loss tangent of 0.025. The total planar area of the proposed antenna (L £ W) is 28 £ 24mm 2 . Both the simulated and experimental result shows that the proposed antenna provides a frequency range compatible with the ultra-wideband (UWB) standard, i.e., 3.5GHz{12GHz frequency band. The radiation pattern produced by the proposed antenna is approximately omnidirectional with in- phase excitation of Surface waves resulting in less cross-polarization level (less than 20dB) compared to its co-polar component for the entire impedance band width. The maximum measured gain for the fabricated antenna is around 6.27dBi with an average e-ciency of above 90% throughout the bandwidth. A linear phase response (phase of S21) accompanied by a constant group delay of 1ns throughout the measured bandwidth makes the proposed antenna a good candidate for UWB applications.

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High gain and low cross-polar compact printed elliptical monopole uwb antenna loaded with partial ground and parasitic patches

This paper presents the design of a 60GHz passive repeater endfire array using dielectric resonator antenna (DRA) elements. The proposed DRA antenna element is loaded with an open-ended microstrip line coupled through a slot, and the reflection phase is controlled by varying the length of this phase-delay line. Based on the working principle of reflectarray, two DRA elements with 180° phase difference are selected with the aid of infinite periodic simulation model in HFSS. A 6×6 array is designed and simulation results demonstrate good endfire performance.

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A 60GHz passive repeater with endfire radiation using dielectric resonator antennas

A planar simple and compact monopole antenna for UWB applications is proposed with CPW feeding. The radiating patch of the antenna consists of a top-cut half-circle together with a triangle on the lower edge. The bottom side of the antenna includes a rectangular defected ground plane with two different symmetrical bevels. By cutting out these bevels on the ground plane, bandwidth coverage of the overall UWB range except 5.4-7 GHz frequency band is provided. To enhance input impedance bandwidth characteristics at 5.4-7 GHz frequency band, dimensions of the triangular part on the lower edge of the patch and top-cut half-circle part on the upper edge are optimized. The overall size of the proposed antenna is 22×20×1 mm3. Simulations are carried out using commercially available ANSYS's HFSS program which uses the finite element method (FEM). Results show that 110% of the impedance bandwidth between 3.6 and 12.2 GHz for VSWR<;2 is achieved. Moreover, antenna has a stable omnidirectional pattern at XZ plane over the frequency band. Also, the presented antenna is fabricated on FR4 substrate and it is measured.

A simple and compact CPW-fed UWB printed monopole antenna with defected ground structures

This paper presents the preliminary design of a 60GHz passive repeater endfire array with dielectric resonator antenna (DRA) elements. The proposed DRA element utilizes simple notches at opposite corners of a square DRA to obtain polarization-conversion. By combining two DRA with notches on opposite diagonals, endfire radiation can be obtained. A 6×1 linear array is optimized and simulated as an initial demonstration.

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A notched dielectric resonator antenna unit-cell for 60GHz passive repeater with endfire radiation

We numerically simulate propagation of a Gaussian beam passing through an array of alternating positive and negative coupling waveguides for difierent inclination beam angle, in presence and absence of nonlinear term. Major difierences are seen in comparison with the constant coupled waveguides analogous. 1. INTRODUCTION The study of linear and nonlinear phenomena in coupled waveguide arrays as an evidence of discrete indexed optical medium has attracted a lot of attention over the past decade and is investigated in one and two dimensions (1). The coupling in waveguide lattices is due to light electric fleld leakage and is mathematically deflned as a speciflc overlap integral between the linear modes of adjacent waveguides. So far the sign of coupling parameter has been considered positive (DC-coupling) in most of the works in this area, where the portion of electric fleld penetrate to flrst adjacent neighbours are in phase with itself. More recently, negative coupling has also been proposed (2), which is physically equivalent to an additional phase shift of … caused by the coupling. A one- dimensional array of parallel and adjacent waveguides that are located in the air or inside a difierent D-electric environment can be studied as such systems. Fig. 1 depicts such a periodic waveguide array arrangement. All waveguide elements are identical and equally spaced from each other. In this article, propagation of a Gaussian beam in arrays of waveguides with alternating positive and negative coupling (AC-coupling), in the absence and in presence of nonlinear phenomenon is studied numerically and compared to homogenous positive coupling case (3). Here Gaussian beam evolution is simulated while propagate along waveguides and its route is investigated by several initial phase difierence of waveguides which is caused by input beam tilt angle. 2. THEORETICAL MODEL

Gaussian Wave Propagation in Alternating Positive and Negative Coupling Waveguide Arrays

In the proposed paper Umbrella shaped Dipole antenna is chosen and its radius is optimized for Millimeter wave band, i.e., 60GHz. The Extended dipole is given Microstrip feed and it is backed by Artiflcial Magnetic Conductor (AMC) ground added with closed cap via holes. In the proposed work the dimensions of Spiral ground and vias are optimized and their combine efiects were used to suppress surface wave efiect, which were responsible for decrement in the antenna performance in terms of antenna gain and e-ciency. The proposed structure is drawn on RT Duriod having permittivity of 2.2 with substrate thickness of 0.45mm. the results are based on simulation, done using IE3D simulator of Zeland Corporation. 1. INTRODUCTION Monopole antenna being low proflle, flnds many application in difierent area. Their compatibility rate with MIC structures is very high, and their fabrication is also very easy, compared to other antenna structure. In this paper Millimeter wave is referred to unlicensed frequency band of 55 to 60GHz. This band now a day's is seen as good candidate for high speed short distance data communication. The high free space attenuation rate for this band limits its application to short distance range only, and that makes it possible for using excellent frequency reuse criteria (1). But when designing the antenna at such a high frequency it is seen that if the substrate thickness is less than quarter wavelength then, the radiated wave which impinges substrate and passes to ground layer will undergo two efiects. Firstly some of the wave will get re∞ected back from ground layer with 180 degree phase shift (in order to maintain node and antinodes criteria of E and H fleld) and causes a destructive interference with the main radiation pattern. Secondly some wave will travel through the ground surface and get difiracted at the discontinuity, since ground used is flnite in nature. This difiracted wave will again interfere with main radiating wave. Thus from both the efiects the performance of the antenna in terms of Return loss, Gain and E-ciency will reduce. For this reason, Antenna with Spiral AMC ground is proposed and further the performance of the proposed antenna is increased by introducing the vias to the structure (3{5), in following sections it will be explained that how surface wave efiects are reduced and their by antenna performance is enhanced. 1.1. Semicircular Monopole Patch Antenna The proposed antenna has a semicircular shape, and is designed on the RT Duriod substrate having relative permittivity of 2.2 with thickness of 0.45mm. The semicircular patch is chosen because of the fact that, for increasing the band width of the simple monopole wire antenna, it has to be replaced with plate elements such as, elliptical, triangular, rectangular, circular or in this case a semicircular (3). The semicircular shape of the proposed antenna is optimized, for getting the band width near 60GHz frequency. The optimization is with respect to the cavity model of patch antenna and IE3D simulator optimizer, in which the semicircle part of the antenna is chosen and for needed frequency the limits of the dimension is given. For best optimized results the structure is flnalized. After flnalizing the design of the antenna the position of the vias was analyzed. Point of placing the vias at the lower end of semicircle and upper end of the Microstrip transmission line is to provide a path to surface wave and to seizes it in vias their by providing a high impedance surface and thus decreasing the efiects of surface wave (5). In following section it can be seen that through this process the radiation e-ciency for the structure is also increased and is su-cient for Millimeter wave band. In Fig. 1 the semicircular monopole patch is shown, here W = 0:26‚, L = 0:73‚, and r = 0:4‚, here ‚ is free space wave length. The feed used is 50 Microstrip feed.

Extended Dipole Antenna with AMC Spiral Ground and Via Holes for Millimeter Wave Application

In the proposed paper, a rectangular monopole antenna with defected ground plane for UWB application is analyzed and experimentally studied. It is found that by making a slot on the ground plane return loss characteristic is improved. From experimental results, the measured impedance bandwidth of the fabricated structure covers a frequency band from 3 to 11 GHz with the central frequency at 6.9 GHz. Above analysis is done using commercially available CST Microwave Studio 2011 software and with optimized result it is fabricated on FR4 substrate having permittivity of 4.4 and thickness 1.6mm. Comparisons of simulated and experimental results were also done. The antenna exhibits Omni directional radiation pattern with < 2 dBi gain for entire bandwidth are presented.

Planar monopole antenna with defected ground plane for UWB application

In this article, a LS band (1.5–2.3 GHz) antenna is presented.Here, the antenna is backed by partial ground and periodic surface wave structure. Both the simulated and experimental result shows that the proposed antenna acquires a bandwidth of 38.8%, that is, 1.5–2.2 GHz and an end fire radiation pattern with a beam width of 108° and maximum gain of 6.5 dbi at 2.1 GHz. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1556–1559, 2012, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26914

G. Shrikanth Reddy

Papers

Extended Dipole Antenna with AMC Spiral Ground and Via Holes for Millimeter Wave Application

Planar monopole antenna with defected ground plane for UWB application

LS band antenna backed by surface wave structure