Design, simulation, and fabrication of low-cost inkjet antennas

2016
Mutlu, Feza
In this study, low-cost inkjet-printed antennas are investigated from the design level to the end-pro duct level. As a substrate, commercial photograph paper is used. Antennas working in various frequency bands are designed using a sophisticated simulation environment based on the multilevel fast multipole algorithm (MLFMA). Antennas are printed via standard, low cost, and commercial printers using conductive 25% alloyed silver ink. After printing, a temperature curing process is applied in order to increase the conductivity of silver ink paths. Four different types of antennas are proposed and studied. As the first type, an S-monopole antenna is designed for both 50 Ω input impedance and microchip input impedance. Measurement results show that 50 Ω tuned antenna resonates at 1.66 GHz with a reflection coefficient of -12.4 dB. As the second type, a small (5 c m x 5.3 cm) symmetric dipole antenna with the input impedance of 50 Ω is introduce d. It resonates at 870 MHz with a reflection co efficient of -14 dB. As the third type, loop-meander antennas are proposed for radio frequency identification (RFID) applications at ultra-high frequency (UH F; 865-868 MHz ) band. First, a loop antenna which is conjugately matched to microchip impedance at 865 MHz is designed. The microchip is connected to the terminals of the antenna using conductive epoxy. Therefore, a working fabricated tag is obtained. Then, meander structures are added to the loop antenna as parasitic elements to increase the reading range of the antenna. For the read range tests, a simple measurement setup is develop ed. Reading range is measured for the loop-meander antennas using a reader which works in 865-868 MHz band with output power of 1W or 30 dBm (ATID AT870 Hand-Held UHF RFID reader). According to the measurement results, the maximum reading range is achieved as 60 cm. As the last and fourth type, cage-dipole antennas are designed by using genetic algorithms. An antenna that is matched to 50 Ω is measured, and it is observed that, it resonates at 1.56 GHz with a reflection coefficient of -23 dB. This antenna is re-designed for RFI D applications to resonate at 865 MHz. Reading range tests are conducted on the developed setup and also on the human body. It is observed that the tag is satisfactorily identified at distances larger than 1.5 meters in a wide range of observation angles. In addition to the designed and tested antennas, this thesis discusses low-cost inkjet printing steps, effects of curing time and temperature in inkjet printing, and importance of the impedance matching for RFID antennas.

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Citation Formats
F. Mutlu, “Design, simulation, and fabrication of low-cost inkjet antennas,” M.S. - Master of Science, Middle East Technical University, 2016.