Synthesis and characterization of gahnite-based microwave dielectric ceramics (MDC) for microstrip antennas prepared by a sol–gel method

Abstract

Gahnite (zinc aluminate) nanoparticle powder is synthesized by a sol-gel method and used to fabricate a microstrip antenna. X-ray diffraction analysis indicates the formation of a face-centered cubic gahnite structure with an average crystallite size of 19.92 nm. The surface morphology of the gahnite is analyzed with field-emission scanning electron microscopy. The presence of water molecules and nitrates within the material is confirmed by Fourier transform infrared analysis. The measured dielectric constant, bandgap and unloaded quality factor of the synthesized powder are 8.70, 4.08 eV and 4592, respectively. The performance of the microstrip antenna is evaluated using return loss, (S11) parameter analysis. The measured impedance bandwidth is 760 MHz in the lowfrequency band and 8.1 GHz in the high-frequency band. The overall performance demonstrates that the fabricated ceramic is suitable for application in a microstrip antenna. Graphical Abstract

Electromagnetic Performances Analysis of an Ultra-wideband and Flexible Material Antenna in Microwave Breast Imaging: To Implement A Wearable Medical Bra

“…Such fluctuation could be explained according to the Maxwell–Wagner model of interfacial polarization and Koop’s phenomenological theory2122. In addition, Debye clarified that because of the persistence of interfacial polarization, the relaxation process extends, thereby increasing the relaxation time compared to the dipole polarization23. The measured dielectric permittivity is 2.64 throughout the frequency band.…”

Preparation and Characterization of Flexible Substrate Material from Phenyl-Thiophene-2-Carbaldehyde Compound

“…The width, W , of the patch depends on the resonant frequency and dielectric permittivity according to the following equation [29]: $W=\frac{c}{2f_r\sqrt{\frac{{\epsilon }_r+1}{2}}}$ where c is the speed of light in a vacuum and f r is the operating frequency. The patch length, L , regulates the resonant frequency and is a crucial design parameter.…”

“…The patch length, L , regulates the resonant frequency and is a crucial design parameter. The effective length, L eff , can be calculated from the following formula [29]: $L_{eff}=\frac{c}{2f_r\sqrt{{\epsilon }_{reff}}}$ …”

“…The effective relative dielectric permittivity is given by [29]: ${\epsilon }_{reff}=\frac{{\epsilon }_r+1}{2}+\frac{{\epsilon }_r-1}{2}{\left[1+12\frac{\mathrm{h}}{\mathrm{W}}\right]}^{\frac{1}{2}}$ where h is the thickness of the substrate. An additional line length (Δ L ) needs to be considered on the either side of the patch because of the effect of the fringing field; this can be calculated as [29]: $\Delta L=0.412\mathrm{normalh}\frac{\left({\epsilon }_{reff}+0.3\right)\left(\frac{W}{h}+0.264\right)}{\left({\epsilon }_{reff}-0.258\right)\left(\frac{W}{h}+0.8\right)}$ …”

“…An additional line length (Δ L ) needs to be considered on the either side of the patch because of the effect of the fringing field; this can be calculated as [29]: $\Delta L=0.412\mathrm{normalh}\frac{\left({\epsilon }_{reff}+0.3\right)\left(\frac{W}{h}+0.264\right)}{\left({\epsilon }_{reff}-0.258\right)\left(\frac{W}{h}+0.8\right)}$ …”