Antenna Operating at 14 GHz
As one application in the high frequency band, an antenna operating at 14 GHz is implemented based on the inkjet printing. The size of the rectangular patch is 7.6 mm × 4.6 mm, and the thickness of the substrate is 0.3 mm. As shown in below, the simulation and measurement results of the reflection coefficient are very similar, but the frequency response is slightly lowered due to the difference in the radius of the circular hole in the ground part for the probe feed. The radiation pattern at the resonant frequency of 14.1 GHz is measured. The antenna gain is 5.3 dBi.
Antenna geometry: Simulation structure (Left) and fabricated antenna (Right)
Antenna Operating at 28 GHz
We also implemented a 2 x 2 array antenna operating at 28 GHz. The size of the rectangular patch and substrate thickness are 21.5 mm × 3.39 mm and 0.5 mm, respectively. As shown in below, the simulation and measurement results of the reflection coefficient are very similar. The antenna gain at 28.3 GHz is 11 dBi. These results, antennas operating at 14 and 28 GHz, imply that the devices fabricated by inkjet printing work well in high frequency.
Fabricated antenna operating at 28GHz
Simulated and measured reflection coefficient of the antenna
Simulated and measured radiation pattern: xz-plane (Left) and yz-plane (Right)
Flexible Circuit
We make flexible circuits with inkjet printing process. Flexible circuits can make previously impossible designs possible. In fourth industrial revolution, small size devices are required a lot. Flexible circuits can fit into small devices of narrow space such as mobile devices because it a 90-degree bending is possible.
Flexible circuit implemented by inkjet printing
Bandpass Filter
A bandpass filter operating in the high frequency band is implemented based on the inkjet printing. In below pictures, bandpass filter sample, the optical image and design of silver metal electrode are shown. Key features of the filter are summarized in the table below. The plot of magnitude (dB) versus frequency (GHz) shows that simulation and measurement results are very similar.
KEY FEATURES
Insertion loss S21 and return loss S11. Simulation and measurement results are very similar.
Bypass Capacitor
Bypass capacitor is implemented based on the inkjet printing. Firstly, BaTiO3 film with dielectric constant Dk=78 and loss tangent Df=0.0063 is fabricated by using BaTiO3 ink. The film is widely used as a capacitor material due to its high dielectric constant. Secondly, by using the film, a bypass capacitor with a capacitance of 100 pF or more can be fabricated. Below design shows four bypass capacitors formed around a bare chip, each of which is difficult to be included inside a semiconductor chip. The capacitors are implemented successively based on the inkjet printing. This product makes it possible to miniaturize semiconductor chips for the purpose of high frequency applications.
