parameters of materials
D.A. Usanov, S.A. Nikitov, A.V. Skripal, M.Y. Kulikov
The possibility of realizing one-dimension photonic crystals in waveguide and microstrip implementations with amplitude-versus-frequency characteristics controlled by pin-diodes and creating on their basis microwave switches, modulators, and high sensitive systems for measuring parameters of materials on microwaves is considered.
To realize a transmission value control in the low-loss transmission window, the pin-diodes matrix was used. It was inserted into the waveguide section together with one-dimension photonic crystal. The controlled voltage was applied to the pin-diodes matrix. It was changed from 0 to 700 mV. The frequency dependencies of the magnitudes and phases of the reflection and transmission coefficients near the low-loss transmission window of the photonic crystal were investigated experimentally for different values of the voltage on pin-diodes matrix.
The possibility to implement an X-band attenuator at the central frequency of low-loss transmission window with small phase error and with controlled by the pin-diodes transmission has been shown. The transmission changes from –1.5 to –25 dB when the voltage on PIN-diodes matrix changes from 0 to 700 mV.
Microwave photonic crystals implemented on microstrip lines with periodically changing width of the stripline conductors and contained ir-regularities such as changed length of one of the microstrip section were considered.
Frequency dependencies of the return losses of the electromagnetic radiation interacted with microstrip photonic crystal loaded with resonant system were investigated. The resonant system was implemented as the 3 pF-capacitance and a coupling loop with PIN-diode 2A523A-4 at the center. This system is functioning as the irregularity in the photonic structure, changing its amplitude-versus-frequency characteristics.
Microstrip photonic structure with the resonant system shows the high sensitivity of amplitude-versus-frequency characteristics of the return losses to the magnitude of the pin-diode direct current.
It has been shown that at different frequencies, both direct and inverse modes of switching the return losses with the maximum value more than 60 dB can be realized.
The change of amplitude-versus-frequency characteristics of attenuation losses when placing dielectric samples above the photonic structure has been considered. Dielectric sample with different dielectric permittivity were placed directly above the structure, above one of its sections, which played as the irregularity in the photonic structure. The influence of dielectric samples on the structure amplitude-versus-frequency characteristics manifests itself in a shift of peaks of attenuation losses by frequency and amplitude.
Selecting the operating frequency and the value of PIN-diode current, one can obtain monotonously increasing or decreasing de-pendencies of return losses on the dielectric permittivity of the sample, as well as dependencies that are characterized by existing of a max-imum at the definite dielectric permittivity value of the sample.
The designs of photonic crystals, which can be used for creation of microwave switches, modulators, and high sensitive systems for measuring parameters of materials on microwaves were suggested.