A nona-band narrow-frame antenna with a defected ground structure for mobile phone applications

Abstract

A nona-band narrow-frame antenna with a defected ground structure for mobile phone applications is presented in this article. From the analysis of the structure, the coupled-fed antenna mainly consists of four parts: bending feeding strip, coupling shorted strip, copper plate and defected ground structure. It can effectively cover LTE700/GSM850/GSM900/DCS1800/PCS1900/UMTS2100/LTE2300/LTE2500 and the ninth band on 3300-4200 MHz (including LTE3500), which may be applied to the future 5G. The size of the nona-band antenna is 80 × 7.5 × 5 mm3, and the defected ground structure is only 55 × 0.5 mm2. This structure effectively widens the bandwidth of the low-frequency band and realizes 2G/3G/4G and possible coverage of the 5G operating band without loading the lumped elements. Thus, it is suitable for smartphone application. A prototype of the proposed antenna is manufactured and measured. The measured −6 dB impedance band-widths in the low, mid and high bands are 340 MHz (630-970 MHz), 1410 MHz (1510-2920 MHz) and 1060 MHz (3160-4220 MHz), respectively. In addition, the efficiency of the antenna is greater than 60% in most of the working frequency bands, and the antenna has good radiation performances.