Two different designs of a dual band patch antenna have been investigated in this paper.By using u-slot patch geometry dual bandoperation has been obtained. The patch antennais simulated by Ansoft HFSS software which is finite element method based simulator. After theantenna performance characteristics such as, inputimpedance, return loss, polar plot are obtained..This observation has provided us sufficient insightto optimize the antenna parameters to meet thedesign requirements. The proposed designs ofthe antenna operate in2.4 GHz band which iscommon to all two designs but the secondoperating band is different. By varying the slotbroadness the second frequency band can beshifted IEEE802.11b (2.45GHz) andIEEE802.11y(3.2 GHz) standards which wouldallow WLAN operation. This patch antenna hasbeen intended to be used in portable devicesthat demand miniaturized constituent parts.
Keywords— Patch antenna, slot, dual band, gain, directivity.
The use of multiband antennas in portable devices like mobile phone, laptop, gaming console etc. is inevitable now-a-days. Due to the concept of miniaturization the size of these devices is shrinking rapidly. Consequently, the antennas must become smaller to fit inside them. This paper aims at presenting three miniaturized dual band u-slot patch antennas for WLAN application. The paper also confirms the technique of shifting resonance frequency by varying the u-slot broadness. Besides, the gain and directivity have been improved in two designs of the patch antenna. Apart from it, emphasis has been given to the miniaturization. At the end, the balance between the dimension and performance of the antenna has been carefully established by parametric study. For brevity, the results of parametric study have been omitted in this paper. A simple patch antenna with basic rectangular patch operates in a single frequency band. A patch antenna intended to operate at a center resonance frequency fr mounted on a substrate having dielectric constant εr would have length L and width W of the patch as found from the following equations neglecting the fringing effect [Abbildung in dieser Leseprobe nicht enthalten] A basic single band rectangular patch antenna can be modified into a multiband antenna by introducing slots in the patch. The shapes and position of the slot play an important role in determining the resonance frequency. The slot shapes like C, E, F, H, L, V, U and many others are well known.