Compact Flexible Three-band Printed Monopole Antenna

Abstract

A novel compact, flexible three-band printed monopole antenna with letter F–like shape is proposed. It is a three-band antenna to cover the LTE bands (0.8, 1.8, 2.6 GHz) with band-widths greater than 100 MHz. Screen-printing technology is used to construct the antenna, with highly conductive ink on a thin, flexible, and high permittivity Preperm TP20556 substrate. Antennas on such materials are of interest in printable electronics which reduces the fabrication cost. The proposed antenna has light weight with small volume and planar configuration. The antenna and application circuitry are aimed to be integrated on same substrate. Advanced Design System ADS, and ANSYS HFSS electromagnetic simulators were both used to design the antenna. CST Microwave Studio was used to do characteristic mode analysis and excitation study of the structure to further understand the working principle. The step-by-step analysis on how various geometrical features affect the antenna characteristics allowed for a better understanding of the working principle of the proposed antenna. We support the ideas with frequency domain, time domain and characteristic mode simulation results. In addition, we discuss challenges that we have faced in modelling and measuring this type of multi-band printed monopole antennas. Antennas have been constructed with copper tape and screen-printing technology. Antennas have been measured with VNA and in the anechoic chamber (Satimo antenna measurement device). Both constructed antennas with ink and copper tape keep the overall characteristics of the simulated ones with triple-band operation at 800 MHz, 1.8 GHz and 2.6 GHz. The copper tape antenna showed a 100 MHz bandwidth with minimum measured total efficiency of 88, 60, and 69 % at the 0.8, 1.8, and 2.6 GHz bands respectively. The ink antenna showed a 100 MHz bandwidth with minimum measured total efficiency of 65, 42, and 46 % at the 0.8, 1.8, and 2.6 GHz bands respectively. The measured maximum gain of the copper tape antenna was 2.54, 2.14, and 4.38 dBi at the 0.8, 1.8, and 2.6 GHz bands respectively. The measured maximum gain of the ink antenna was 1.27, 1.31, and 3.48 dBi at the 0.8, 1.8, and 2.6 GHz bands respectively.