Monageng Kgwadi

On-demand printing of antennas for TV white-space communications

We present a meander-line monopole antenna produced by thermal-transfer metallic printing onto a polyester substrate. The antenna is immediately useful because no curing is required. The antenna has a measured fractional bandwidth of 26% centred at 864 MHz and directivity of 4.3. The measured and simulated s11 parameter agree well. We show the radiation pattern measured in a near-field spherical scanning system. This study advances the development of low-cost, environmentally friendly antennas for deployment in the Internet of Things.

Possibilities of Fabricating Copper-Based RFID Tags With Photonic-Sintered Inkjet Printing and Thermal Transfer Printing

This letter studies the possibilities of manufacturing copper-based passive ultrahigh frequency (UHF) radio frequency identification (RFID) tags using inkjet and thermal printing on two substrate materials, polyimide (Kapton), and a polyester-based substrate (Flexcon THERMLfilm). Both printing methods are tested to fabricate different tag designs, and the performance of successfully printed tags is evaluated using wireless measurements. Measurement results show that both printing methods, while using copper material, can be used to effectively fabricate passive UHF RFID tag antennas on selected substrates.

Characterization of nanoparticle inks on a novel polyester-based substrate for manufacturing of passive UHF RFID tags

We characterize two nanoparticle inks for the fabrication of low-cost passive UHF RFID tags on a novel polyester-based substrate (Flexcon THERMLfilm). We developed optimized printing parameters for Silver (Harima NPS-JL) and Copper (ANI Cu-IJ70) inks, fabricated the tag antennas and sintered them using thermal and photonic sintering. The tag performance is evaluated through wireless tag measurements, with comparison to the same inks and antenna geometry on the well-known polyimide substrate Kapton. The paper discusses the compatibility of the two nanoparticle inks and their sintering on the novel substrate.

Bow-tie antenna for terahertz resonant tunnelling diode based oscillators on high dielectric constant substrate

In this paper, a broadband bow-tie slot antenna is presented. The coplanar waveguide (CPW) fed antenna is fabricated on an InP substrate for same chip integration with the promising resonant tunnelling diode (RTD) terahertz (THz) oscillator which has the capability of room temperature operation and with relative high power. The antenna exhibits a very wide bandwidth (return loss S11 <;-10 dB) around the design frequency (300 GHz). However, the radiation pattern is degraded because of the large dielectric constant of the InP substrate. A technique to overcome this problem employing a reflector ground plane underneath a thin substrate of low dielectric constant is presented. Initial simulation results of this technique are reported and experimental validation at lower frequency (17 GHz) shows the feasibility of the concept.

Parametric study of broadband tunable helix antenna matching

Helical antennas are versatile, but they have almost purely resistive input impedance, so lumped element matching networks inevitably incur power loss. We investigate an alternative matching technique that claims up to 1:1 VSWR with post-fabrication tuning, by using an extension above the ground plane. However, our results show that the lowest return losses may actually occur outside the desired band of operation. We show that the matching technique is dependent on the geometry of the matching structure. In an attempt to bring the best match back inside the operating band, we expand the parameter space of the ground plane extension by considering a double bend which we expect to give more linear impedance transition. We achieved broadband operation with up to 20% fractional bandwidth for -15dB return losses within the targeted 2.4GHz LAN frequency band. Further work is required to derive design equations for this matching geometry.