Advances in Microelectronic Engineering (AIME) Volume 1 Issue 4, October 2013 www.seipub.org/aime 73 A Low-Cost Microstrip Antenna for Wireless FidelityApplication Antenna and Microwave Components Asma Kamalvand 1 , Alireza Monajati 2 , Mohammad Ojaroudi 3 1,2 Department of Electrical Engineering, Shahre-Rey Branch, Islamic Azad University, Tehran, Iran, 3 Young Researchers Club, Ardabil Branch, Islamic Azad University, Ardabil, Iran. 1 asmakamalvand@hotmail.com; 2 alireza_monajati@iausr.ac.ir; 3 m.ojaroudi@iauardabil.ac.ir Abstract In this paper, an attempt has been made to design a new microstrip-fed monopole antenna for wireless fidelity (Wi-Fi) systems. The proposed antenna is fabricated on the FR4 substrate with dielectric constant of 4.4. By cutting a pair of inverted L-shaped slits in the square radiating patch, a new resonance at lower frequency (2.4GHz) can be achieved, also by inserting two L-shaped slits in the ground plane, the antenna achieves good dual-band operation. The measured impedance bandwidth for l0 dB return loss is from 2.05 GHz to 2.76 GHz (29.9%) and 4.6 GHz to 5.46 GHz (17.0%), covering the 2.4 and 5.2 GHz wireless fidelity operating bands. Simulated and experimental results obtained for this antenna show that the proposed monopole antenna has a good antenna gains and radiation behavior, with a small dimension of 12 × 18 mm 2 . Keywords Dual Band; Wireless Fidelity; L-Shaped Slit; Monopole Antenna. Introduction Wireless communications have been developed widely and rapidly in the modern world especially during the last decade. In many applications of wireless communications such as Personal Communications Services (PCS), Bluetooth, IEEE 802.11 Wireless Local Area Networks (WLAN, e.g. Wi-Fi i.e. IEEE 802.11a, 802.11b, 802.11g, 802.11j etc.), it is desirable to use multi-band antennas that are small in size. One type of wireless communications is Wireless Fidelity (Wi-Fi). A Wi-Fi enabled device such as a personal computer, video game console, smart phone or digital audio player can connect to the Internet within range of a wireless network connected to the Internet. One method to obtain multi-band operation is a shorted T- shaped monopole antenna with antenna gain that is about 2.0-2.6 and 3.2-3.7 dBi for the 2.4 and 5 GHz band respectively. Printed dual band monopole antenna provides two operating frequency bands for Wi-Fi operation with near about 3 and 5.5 dBi gains at frequency 2.4 and 5.8 GHz respectively. If the monopole antenna is designed in ring shaped or hook shaped, the gain is not over 2.8 and 4.29 dBi at frequency 2.4 and 5 GHz respectively. In this paper, a novel design of a dual-band monopole antenna is proposed which has many advantages such as low-cost, wide bandwidth and easy simple structure. Pair of inverted L-shaped slits in the radiating patch is embedded in order to achieve a new resonance at 2.4 GHz, and also a pair of L-shaped slits has been cut in the ground plane that with this design a good dual-bad function can be achieved. Desirable return loss and radiation pattern characteristics are obtained in the frequency band of interest. Antenna Design The proposed monopole antenna fed by a microstrip line is shown in Fig 1, which is printed on a FR4 substrate with the thickness 0.8 mm. As shown in Fig. 1, the proposed antenna consists of a square radiating patch with two inverted L-shaped slits and a modified ground plane with two L-shaped slits. The square patch has a width of W. The patch is connected to a feed line with the width of f W and the length of f L . On the other side of the substrate, a conducting ground plane with width sub W and length gnd L is placed. The width f W of the microstrip feed line is fixed at 1.5 mm. The proposed antenna is connected to a 50Ω SMA connector for signal transmission. The optimized values of proposed antenna design parameters are as follows: mm W sub 12 = , mm L sub 18 = , mm h sub 8 . 0 = , mm W f 5 . 1 = , mm L f 7 = , mm W 10 = , mm L 10 = , mm W 3 1 = , mm L 7 1 = , mm W 5 . 2 2 = , mm L 5 . 0 2 = , mm W S 75 . 3 = , mm L S 3 = , mm W S 25 . 4 1 = , mm L S 5 . 0 1 = , and mm L gnd 4 =