Analysis of microstrip low pass filter at terahertz frequency range in finite difference time domain method for radar applications

Abstract

Terahertz Technology is a promising newer technology for various applications in wireless and radar communication namely tracking and detecting radar targets. The challenging aspect of radar transmitters in the target detection process is spurious harmonic signals that affect the communication path between radar transceivers. The spurious signal can be neglected by a strong filtering method. Filtering is vital in radar transmission to avoid high spurious emission level signals. Low pass filtering at terahertz frequency range (LPFT) in microstrip structure defined in the chapter analysis to avoid the harmonics above the cut-off frequency. In this chapter, the analysis part of microstrip structured LPFT is implemented under finite difference time domain analysis at (0.3 THz to 0.5 THz) cut-off frequency. Finite difference time domain (FDTD) is the three-dimensional approach commonly used for the analysis in higher frequency applications. In this FDTD method, Maxwell equation’s partial derivatives are centred to finite frequency by discretization. LPFT 3D-plot is characterized by the signal factors of the input signal, reflected signal, and passed signal concerning time. Scattering parameters |s11| and |s21| are characterized by frequency and magnitude plots with an insertion loss of 0.3 dB. Full-wave analysis of LPFT is compared with Chebyshev and Butterworth filter at terahertz cut-off range is implemented. The comparison plot of attenuation versus relative frequency and characteristic impedance versus dielectric constant is shown with FDTD results with good agreement.