The International Alumınıum-Themed Engineering and Natural Sciences Conference in Seydişehir/TURKEY (IATENS’19), October 4-6 2019 Two-Layer Microstrip Patch Antenna Performance Using Two Different Dielectric Materials Miriam Mumputu a , S.Sinan Gültekin a , Dilek Uzer a and Özen Bayraktar a a Dept. Electrical and Electronics Engineering, Konya Technical University, Turkey E-mail: mumputum2016@gmail.com, ssgultekin@ktun.edu.tr, duzer@ktun.edu.tr, ozen_bayraktar@yahoo.com.tr Abstract In this study, two-layer dielectric microstrip patch antenna designs at 2.5 GHz frequency have been realized for high antenna performance. Circular and rectangular slit arrangements on the patch are made to improve the result. In this way antenna dimensions have decreased significantly, and performance has increased. FR4 and Duroid were used as dielectrics. The final antenna design with a small size (40x30mm), two-layer substrate and high-performance as 372 MHz (14.88%) bandwidth was obtained with 9.89 dB gain, - 35.43 dB return loss at 2.495 GHz. Keywords Two-layer microstrip patch antenna, slit, gain, return loss, bandwidth. 1. Introduction Antenna is a device which can radiate or receive electromagnetic waves. An antenna can be classified as transmitting and receiving. It is also identified that the same antenna can be used for transmission and reception of electromagnetic waves. The important property of an antenna is the ability to focus and shape the radiated power in space. The present communication scenario uses microwave frequencies for efficient transmission and reception. The term microwave is used for the radiations with frequencies 1GHz to 300GHz [1]. The microstrip antenna has been used due to his small size, easy integration, light weight, and low profile, [2]. Nevertheless, the microstrip antenna intrinsically have a narrow bandwidth. To achieve broader bandwidth performance and to resolve the limitation of narrow impedance bandwidth, different techniques have been proposed like Slotted patch antenna, stacked shorted patches, parasite patches, probe fed Stacked antenna and the multi-layer microstrip patch antenna structure [3]. In this paper a multilayer microstrip antenna with Slotted patch is presented to enhance the bandwidth. The simulation of the antenna has been done by using HFSS (High Frequency Structural Simulator- Ansoft). 2. Dielectric Material Dielectric constant and loss tangent are the important parameters need to be considered while selecting dielectric material cost or substrate. In this study FR4 with 4,4 of permittivity and 0.02 tangent loss and duroid™ with permittivity 2,2 and 0,0009 are used due to low cost, low dielectric constant, low lost tangent. 3. Design of Antenna The dimensions of the antenna were calculated using the following formulas; Calculation of the width = 2 √ 2 (+1) (1) W is the width of the patch and h is the height of the substrate Calculation of Effective Dielectric constant = +1 2 + −1 2 [1 + 12ℎ ] −1/2 (2) Calculation of Effective length (Leff) = 2 √ (3) Patch resonant length L is given by (L) = − 2∆ (4) Where is the length extension The following expressions were used for the thickness and dielectric constant of the bilayer dielectric [5]. h = h1 + h2 (5) Ɛeff = (Ɛeff1 + Ɛeff2) / 2 (6) The proposed antenna is designed by using two layers of substrate: FR4 as the lower substrate and Duroid (tm) the upper substrate and the patch which is slotted by the circular and rectangular slot. The size of the FR4 and Duroid substrates are length L=50mm and width W=59mm, thickness of 1.6mm and 1.58mm and dielectric constant of εr=4.4 and 2.2 respectively. The geometrical dimensions of the patch that is managed multilayer microstrip antenna is respectively length Lp=30mm and Width Wp=40mm. Figure 1 shows the structure of multilayer microstrip antenna with patch slotted. In this study the coaxial feed is chosen. The outer conductor of coaxial probe is connected to