Low-cost thin film patch antennas and antenna arrays with various background wall materials for indoor wireless communications

Abstract

The present study introduces an inkjet-printed flexible coplanar waveguide (CPW) patch antenna array concept. Single antenna and four-element antenna arrays were characterized, which were attached to a sub-miniature version A (SMA) connector via an innovative solderless, 3-D printed "plug and play type" tightener. 
Furthermore, indoor wireless communication and internet of things (IoT) scenarios with commonly used wall materials including gypsum and plywood board, on which the patch antennas and antenna arrays can be attached, were also presented. In order to validate the concept, design and fabrication iterations in parallel with numerical and experimental investigations were executed. To elaborate, single antenna and antenna array configurations without and with wall materials were characterized to see their functionality at 2.4 GHz resonance frequency with beyond 300 MHz bandwidth, respectively. The results demonstrated that the investigated configurations fulfill the short-range radio transmission and can be utilized, e.g. for indoor backscattering type communications and wireless sensing applications, as an affordable and versatile alternative for their conventional counterparts. Being attached to their corresponding background materials, single antenna specimens were measured to have return losses beyond 18 dB and peak gains around 1 dBi while higher peak gains above 6 dBi were detected for antenna arrays.
Moreover, the antenna arrays can enable multiple-input and multiple-output (MIMO) communication. The proposed arrays had diversity performance in terms of return losses higher than 15 dB, isolation more than 20 dB, envelope correlation coefficient (ECC < 0.001), diversity gain (DG > 9.95 dB), mean effective gain (MEG < -3 dB), power ratio factor (k < 0.5 dB), and channel capacity loss (CCL < 0.4 bits/s/Hz).

Microstrip resonators on polyethylene terephthalate substrates realized by direct-write technology

“…Previous studies show the usability of printed transmission interconnects [10] up to ones of GHz with a low attenuation constant [11]. Also, conducted studies describe the realization of printed structures, such as antennas [12,13], sensors [14], filters [15], and other printed structures. For example, authors [16] successfully realized a ring resonator using Aerosol Jet Printing (AJP) technology.…”