Compact multi-band antenna and matching circuit for LTE low frequency bands

This article introduces a coupled planar antenna which is made of a driven monopole antenna and a parasitic element fed through a via. These elements are etched in a no-ground part, which is small compared to the Printed Circuit Board (PCB) size. The antenna has several resonant modes enabling three wide operating bands, which respectively cover the LTE700/GSM850/900, GSM1800/1900/UMTS, LTE2300/2500/2700 and LTE3400/3600 standards. A prototype whose size is suitable for mobile phones has been realized. There is a good agreement between simulation and measurement in term of return loss. Also in this publication, an analysis of the impact of this antenna on the performance of power amplifiers is conducted. It is followed by a practical solution of matching circuit. The effects of the antenna´s impedance and the matching circuit are demonstrated through the study of the output power of the power amplifier.