文档介绍：Chapter 4 – New Microstrip Filter Design
C H A P T E R 4
New Microstrip Filter Design
. Introduction
munications systems require preselect filters with enhanced properties.
This chapter presents the research on novel microstrip filters. The technology required
by the newly developed filters is economical, no short-circuit elements and no lumped
components are needed. The designs can be easily extended for planar HTS
technology. In this chapter, an emphasis is put on the development of dual mode filters
and filters with cross-coupled novel resonators. This introductive section presents the
work on low-pass and band-pass conventional filters.
. Low Pass Filter
The layout of a 7 pole Chebyshev low-pass filter with dB in-band ripple [1] is
shown in Fig. .
Figure . Picture of the low pass filter simulated with FDTD.
The filter can be used in a munication receiver in the DCS 1800
standard. The filter was design and manufactured on a substrate with dielectric constant
εr= and thickness h= mm.
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Chapter 4 – New Microstrip Filter Design
The newly developed FDTD method was used for accurate design of the above
low-pass filter. An uniform rectangular FDTD grid was used with mesh sizes:
∆x= mm, ∆y= mm and ∆z= mm. The time step was ∆t= ps and
the Gaussian pulse half bandwidth was T=15 ps, with the initial delay T0=60 ps. The
computational domain was bordered by the ground plane as a perfect conductor at one
side and by perfectly matched layers (PML) on the other sides. All non-homogeneous
perfectly matched layers (NH-PML) were identical. The NH-PML was 16 cells thick
and its parameters g=2 and σ= mS/m.
0
-10
-20
S21 [dB] -30
-40
-50
0 2 4 6 8 10 12
Frequency [GHz]
Figure . Response (S21) of the low pass filter for DCS1800 – simulated
(continuous line) and measured (dotted line).
Fig. shows that