Compact transparent conductive oxide based dual band antenna for wireless applications

Abstract

A dual-band compact transparent antenna is proposed. The antenna resonates at 3.38 GHz and 4.24 GHz band for WLAN and WiMAX applications. The antenna is engineered by inducting slots on conducting surface to meet the target resonance frequencies. These tailored slots, being one of the most adopted conventional techniques, are able to provide adequate antenna tuning. The antenna has dimension of 0.33λ ×0.33λ at lower frequency and 0.42λ×0.42λ at higher frequency. Conducting Oxide materials, AgHT-8 and AgHT-4, are coated over glass substrate to generate fringing fields. Resistivity of AgHT-4 is lesser compared to AgHT-8 while the optical transparency of AgHT-8 is more than AgHT-4. Antenna having more optically transparency significantly increases possibility of finding installation location and also enables integration with glass of building for WiFi and WiMAX signal propagation. The use of transparent antenna significantly reduces the space constraints as the visibility is not being compromised so most of the windows of the buildings and vehicles having glass structure can be utilised for its incorporation. Voltage Standing Wave Ratio (VSWR) of 1.42 and 1.31 at target frequencies were noted. The measured impedance bandwidth of antenna is 3.55% and 3.30% at 3.38 GHz and 4.24 GHz respectively. In effort to make an antenna electrically compact, a due compromise in antenna gain is inevitable. The conducting oxide material coated over bottom surface of planar antenna is effectively able to reflect the energy back towards antenna boresight. The antenna gain of around 1.1 dBi and 0.95 dBi at lower and higher resonance respectively is reported. The simulated and measured results illustrate good agreement.