Traditionally, the metamaterial (MTM) lines have been
synthesised by periodically loading a host transmission line (TL) with
series capacitors and shunt inductors [1]. They support a backwardwave
fundamental harmonic and hence a negative index of refraction
when arranged in the form of two-dimensional or three-dimensional
grids [1]. These lines have been employed to build compact wideband
phase shifters, filters and other electromagnetic devices [2]. In this
Letter, we propose a metamaterial-based bandpass filter that is obtained
by loading the traditional MTM lines with an additional shunt capacitor.
This extra capacitive loading provides more freedom in controlling the
cutoff frequency of the fundamental mode and the subsequent stopband.
Furthermore, varactors can be employed to tune the amplitude
and phase response of the resulting bandpass filter.
in this article, A bandpass filter is constructed by loading a left-handed metamaterial
transmission line with an additional shunt capacitor. The shunt capacitor
provides more freedom to control the passband characteristics of the
resulting metamaterial line. A bandpass filter is designed with a centre
frequency that is tunable from 0.45 to 0.65 GHz.