Internal fork-shaped wideband monopole antenna with a parasitic sleeve for ultra-high-definition television applications

A simple and compact internal fork-shaped monopole antenna with a parasitic sleeve is proposed for operation in the ultra-high frequency (UHF: 470-771 MHz) band for ultra-high-definition television (UHD-TV) applications. The internal antenna is directly implemented into a 49-in TV model on which its bezel frame (made of PC-ABS with ε_r = 3.5 and tanδ = 0.005) is used as a substrate for antenna design. The structure and operation bandwidth of the internal antenna are restricted by the limited space and longitudinal bezel frame. Therefore, the fork-shaped monopole structure with meandering and folding strips is applied, forming a capacitive coupling effect to reduce the antenna size and to enhance the impedance matching. A parasitic sleeve is added and encircled around the monopole to generate additional resonances, hence further broadening the operating bandwidth to cover the entire UHF band. The antenna is then bent to form a three-dimensional structure with a compact dimension of 275 × 17 × 5 mm³, allowing it to be tightly fitted on the bezel frame of the TV model. The final tested antenna achieves a peak gain of 4.7 dBi and an efficiency of more than 60% over a broad −6 dB reflection bandwidth of 60.3% (440-820 MHz).