located around the ends of the slots.
It is interesting to see that the current density distribution is distorted
by the meander spur-line, which
yields the current flow rerouting.
Simulated insertion loss performances of the proposed filter with
different slot lengths are presented
in Figure 5. The center operating
frequencies of the filter are approximately 2.17, 2.38 and 2.56 GHz for S
= 17 mm, 19 mm and 21 mm, respec-
tively. The center operating frequency
is changed by 18 percent. Therefore,
the simulated results show that the
passband can be adjusted greatly by
the slot length. Correspondingly, the
transmission zeros are obviously controlled by this physical parameter.
CONCLUSION
In this article, a dual-mode square-patch filter with meandered spur-lines
is introduced and verified by measure-
ments. Compared to a traditional dual-mode square patch filter, the proposed filter provides a 36 percent size
reduction with a lower insertion loss
of -0.9 dB. Interestingly, it is found
that the current density distribution
can be distorted by meander spur-lines, which yields the current flow
rerouting. This compact dual-mode
BPF with low insertion loss has a good
prospect in microstrip circuit applications. n
References
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Haiwen Liu received his BS degree in
electronic systems and his MS degree in radio
and remote sensing from Wuhan University,
Wuhan, China, in 1997 and 2000, respectively,
and his PhD degree from Shanghai Jiao Tong
University, China, in 2004. He is currently
a professor in the school of information
engineering at East China Jiaotong University,
Nanchang, China. His main areas of research
include radio systems and microwave RF IC
design.
Xiaohua Li received his BS degree from the
School of Information Science and Technology,
Southwest Jiaotong University, in 2006. He is
currently pursuing his master’s degree from
Southwest Jiaotong University, in collaboration
with the Chinese Academy of Science.
