Radioengineering (Apr 2018)
Design of Miniaturized 10dB Wideband Branch Line Coupler Using Dual and T-Shape Transmission Lines
Abstract
This paper presents a design mechanism of miniaturized wideband branch line coupler (BLC) with loose coupling of 10 dB. Dual transmission lines are used as a feed network which provides a size reduction of 32% with a fractional bandwidth (FBW) of 60% for 10±0.5 dB coupling but return loss performance is found to be poor in the operating band. For further improvement of return loss performance as well as for size reduction of the BLC, a T- shape transmission lines are used instead of series quarter wavelength transmission lines, and hence the overall size reduction of around 44% with FBW of 50.4% is achieved. The return loss and isolation performance is found to be les than 15 dB in the entire operating band (2.5–4.1 GHz) with respect to design frequency 3G Hz. The proposed BLC is analyzed, fabricated and tested.
