IOSR Journal of Electronics and Communication Engineering (IOSR-JECE) e-ISSN: 2278-2834,p- ISSN: 2278-8735. Volume 6, Issue 4 (May. - Jun. 2013), PP 01-06 www.iosrjournals.org www.iosrjournals.org 1 | Page Four-Element Triangular Wideband Dielectric Resonator Antenna excited by a Coaxial Probe Amit Kumar, Utkarsh Besaria, Rajeev Gupta Galgotias University, S R Group of Institution, MNNIT Allahabad Abstract-This paper numerically examines an array of four dielectric resonant antenna of equilateral triangle shape. The Structure provides wideband low profile monopole-like antenna. As much as 30.90 % matching bandwidth (S 11 <-10 dB) with monopole-like radiation pattern over the entire band has been achieved with 6.357 dBi peak gain. The geometry is a four equilateral triangular dielectric volume over a ground plane, and is centrally excited by a coaxial probe to provide a broadside radiation pattern. An approximate expression is used to compute the resonance frequency. Results are simulated using CST (Computer Simulation Technology) Microwave Studio Suite 10. Keywords-Dielectric resonator (DR), triangular dielectric resonator antenna (TDRA), S 11 (S-Parameter), perfect conductor (PEC), Impedance Bandwidth (IBW). I. Introduction Dielectric resonator has been used for energy storage for many years. Presently, DR has found its new application as a radiator in microwave circuits. Open dielectric resonators (DRs) offer attractive features as antenna elements [1]. Some features are small size, mechanical simplicity, high radiation efficiency (due to no inherent conductor loss), relatively large bandwidth, and simple coupling schemes to nearly all commonly used transmission lines. In addition it has the advantage of obtaining different radiation characteristics using different modes of the resonator [1-3]. The radiation Q factor of a DR antenna depends on its excitation modes as well as the dielectric constant of the ceramic material. The Q-factor increases and hence the bandwidth decreases with increasing dielectric constant and vice-versa. For this reason, DRs of relatively low dielectric constant are always used in antenna applications [4]. It was found that some geometry might have a wider bandwidth or better linear polarization characteristics than others. The advantage of the triangular DRA is that it offers a smaller area than either a cylindrical or rectangular DRA for a given height and resonant frequency. This paper presents the simulation of a four element Triangular wideband dielectric resonator antenna excited by a coaxial probe. The paper is organized as follows; Section II provides the basic theory of DRA. Details of the proposed antenna structure are provided in Section III. The simulation results of the proposed antenna structure have been presented and discussed in Section IV and finally, Section V provides Conclusions. II. Theory The triangular-shaped DRA, shown in Figure 1, has been introduced as a candidate for low-profile applications. As an example, a high-permittivity, low-profile triangular DRA was designed with   = 82, h=1.1 mm and a=20mm [5]. This DRA was found to have a 5% IBW. To achieve the same resonant frequency, a cylindrical DRA of the same height and permittivity would require a radius of a=7.55 mm, while a rectangular DRA would require dimensions of w=d=19 mm. Thus the size of the triangular DRA would be about 92% that of the cylindrical DRA and about 48% that of the rectangular DRA. The resonant frequency of the TM lmn modes of an equilateral triangular DRA (where l+m+n= 0) can be estimated using the transcendental equations derived from a waveguide model [5]. The first subscript l in the notation TM lmn states the order of the Bessel functions of the first and second kind which must be used to calculate the resonant frequency of that mode, the second subscript m in the designation of the mode denotes the order of magnitude of the root which is used to calculate the resonant frequency, the third subscript n is merely a coefficient in the argument of a trigonometric function which enters into the expressions for the electric and magnetic fields inside the cavity. The resonance frequency is predicted using a simple waveguide mode of a magnetic wall. Tangential field continuity to the surface of the dielectric interface at z=±h will result in the transcendental equation [3]. k z h k z k z 0 ) 2 tan(    And k z r k z    1 0  … (1) where : h p k z 2   , p = 1,2,3…. Where   and   0 are the wave numbers in the z-direction in the dielectric and free space, respectively. The dielectric resonator height h can be obtained from (1) as [3]