Microwave Photonic Band Gap Research Articles

Characterization of microwave photonic band-gap structures with bandpass filter applications

Microwave photonic band-gap (PBG) structures are well known for their superior ability to generate a band stop effect at a certain frequency range. Together with the microstrip transmission line structure, PBG can be utilized as a filter exceptionally well since the periodic perforation patterns can be implemented easily in the ground plane. In this research work, square perforations of different dimensions are constructed in the ground plane of a microstrip transmission line to achieve a double band stop PBG structure. Thus, the transmission ability of the microstrip line is being blocked at different frequency ranges to create a bandpass filter. It is found that the bandpass frequency is strongly dependent on the dimension to period distance ratio. It is demonstrated in both simulation and measurement that the bandpass region can be created at high frequency above 10GHz.

Magnetic photonic band-gap material at microwave frequencies based on ferromagnetic nanowires

We present an experimental investigation of a class of microwave photonic band-gap (PBG) materials, in which the magnetic permeability μ varies periodically within the material. This material is fabricated using a periodic arrangement of arrays of magnetic nanowires. As for dielectric or metallic PBG, the band-gap behavior varies with the geometrical parameters fixing the spatial periodicity of the magnetic structure. The magnetic photonic band gap is induced by the presence of a ferromagnetic resonance effect in the vicinity of the band gap.

Photonic band gap formation by microstrip ring: A way to reduce the size of microwave photonic band gap structures

We show that a microstrip ring with a narrow gap exhibits a photonic band gap (PBG) that is generally believed to be created by a periodic array. The discontinuity of impedance at the narrow gap induces multiple reflections with fixed phase correlation necessary to make the PBG. We also discuss the PBG frequency tuning achieved by applying an external voltage on a varactor mounted on the gap and applications of this PBG ring as a tunable band stop filter and a microwave switch.

Transmission line–periodic circuit representation of planar microwave photonic bandgap structures

Planar photonic bandgap structures have been modeled using the theory of transmission lines and periodic circuits. The method allows for fast and accurate computation of the dispersion diagram, and thus prediction of the stopbands for two directions of propagation. Results obtained by the proposed analytic method are in agreement with previously published numerical data for two structures. Additional numerical evaluations of the reflection phase with the finite-difference time-domain (FDTD) method confirm the validity of the analytic model within the limits of its applicability. They also further confirm previous observations that wave propagation in directions other than two principal axes results in a narrower stopband. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 15–19, 2001.

Transmission line–periodic circuit representation of planar microwave photonic bandgap structures

AbstractPlanar photonic bandgap structures have been modeled using the theory of transmission lines and periodic circuits. The method allows for fast and accurate computation of the dispersion diagram, and thus prediction of the stopbands for two directions of propagation. Results obtained by the proposed analytic method are in agreement with previously published numerical data for two structures. Additional numerical evaluations of the reflection phase with the finite‐difference time‐domain (FDTD) method confirm the validity of the analytic model within the limits of its applicability. They also further confirm previous observations that wave propagation in directions other than two principal axes results in a narrower stopband. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 15–19, 2001.

Duplexer using microwave photonic band gap structure

We propose a frequency selective duplexer using microwave photonic band gap (PBG) structures. It uses two different PBGs to control the propagation of electromagnetic waves in the microwave region. In this structure, an additional narrow reflection band appears in the transmission spectrum when the PBG structure is not properly located relative to the T junction. By considering multiple reflections, it is proved that this additional reflection band in each PBG structure results from the interference between the input wave and the reflected wave from the other PBG structure. An effective way to prevent this interference effect is also discussed.