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978-1-7281-6921-7/20/$31.00 ©2020 IEEE
A Planar High Pass Filter with Quasilumped
Elements for ISM, Wimax and Wlan Applications
Amal Kadiri
LMIET laboratory FSTS
Hassan 1st University
Settat, Morocco
a.kadiri@uhp.ac.ma
Abdelali Tajmouati
LMIET laboratory FSTS
Hassan 1st University
Settat, Morocco
tajmoua@gmail.com
Issam Zahraoui
LIMIE laboratory
ISGA
Casablanca, Morocco
zahraoui.issam84@gmail.com
Abdo-Rahmane Anas Laaraibi1
LMIET laboratory FSTS
Hassan 1st University
Settat, Morocco
abdorahmanelaaraibi@gmail.com
Mohamed Latrach
RF-EMC research group
ESEO- IETR,
Angers Cedex 2 - France
Mohamed.LATRACH@eseo.fr
Abstract—This paper presents a quasilumped Microstrip
structure High Pass Filter having a cutoff frequency 2.5 GHz. The
quasilumped elements are used with the objective of obtaining the
behavior of a high-pass filter with high bandwidth, reducing the
size of the filter and improving the electrical performances. The
proposed filter is designed on an FR-4 substrate having a thickness
of 1.6mm, a dielectric permittivity constant of 4.4 and loss tangent
of 0.025. The proposed filter is optimized and validated by using
three electromagnetic solvers (ADS, HFSS and CST-MWS).The
whole area of the proposed circuit is 19 x 16 mm2.
Keywords—Microstrip High pass filter, quasilumped element.
I. INTRODUCTION
Modern Telecommunications systems are reaching an
increasingly large number of people, which leads inexorably to
intensive use of the microwave range. In many applications,
the low in-band and wide-band stop filter is very important
because it can significantly improve the signal quality in the
band by removing as much of the built-in power from out-of-
band interference as possible. In addition, the filter should be
compact and inexpensive to manufacture.
A filter is an electronic circuit, characterized by a transfer
function, which performs a signal processing operation. It is
based on the coupling between several resonant cells which
ultimately form a certain model in terms of losses, transmission
and reflection. It attenuates certain components of a signal on
one frequency band and lets others pass in another frequency
band called bandwidth.
Planar technologies consist of a substrate which is in the
form of a dielectric plate. Thin metallic layers are deposited on
one or both sides of the substrate.
The filter in localized elements consists of capacitors in
series and inductors in parallel. Its behavior at low frequencies
remains respectable, but when the frequency is increased this
set loses its efficiency, hence the transition to Microstrip
technology [1-3].
A high pass filter is a filter that lets high frequencies
through and attenuates low frequencies, that is, frequencies
below the cutoff frequency. High-pass Microstrip filters can
also be designed by using more modelling techniques to obtain
more precise and faster performance, among these techniques
we find the QLE techniques [5-7].
Quasi lumped element (QLE) filters have a size advantage
over distributed filters. QLE filters could be smaller than
equivalent distributed filters and can realise filters with large
bandwidths [4].
High pass filters constructed from quasilumped elements
may be desirable for many applications, provided that these
elements can achieve good approximation of desired lumped
elements over the entire operating frequency band [8-11].
To obtain the parameters of a high pass filter with QLE we
use the following equations [2]:
[]
5
( ) 3.937 10 ( 1) 0.11( 3) 0.252
r
CpF l n
ε
−
=× + −+
(1)
With n is the number of fingers, w is the width of the
fingers. For n given, it is necessary to respect the two
conditions:
≥ℎ≫
Where s is the space between the fingers and h the height of
the substrate.
And for the dimensions of the short-circuited stub which
the equivalent of the inductance we can use the following
equations:
2020 IEEE 2nd International Conference on Electronics, Control, Optimization and Computer Science (ICECOCS) | 978-1-7281-6921-7/20/$31.00 ©2020 IEEE | DOI: 10.1109/ICECOCS50124.2020.9314620
Authorized licensed use limited to: Universite de Rennes 1. Downloaded on March 20,2023 at 09:30:39 UTC from IEEE Xplore. Restrictions apply.
2
2
tan
cc
gc
l
jZ j L
πω
λ
=
(2)
For
/1Wh≥
0.5
11
112
22
rr
re
h
W
εε
ε
−
+−
=+ +
(3)
1
1.393 0.677 ln 1.444
re
WW
Zc hh
η
ε
−
=++ +
(4)
With η=120π Ohm
300
()
g
re
mm
fGHz
λε
=
(5)
2/
g
and l
ββπλ θ
==
(6)
II.
DESIGN
SPECIFICATIONS
The filter in localized elements consists of capacitors in
series and inductances in parallel.Fig.1. Its behavior at low
frequencies remains respectable, but when the frequency is
increased, this assembly loses its efficiency, hence the switch
to Microstrip technology.
Fig. 1.
high-pass filter in localized elements
The calculation of low pass filters allows the calculation of
high pass filters. For that one can pass by the law of
chebyshev. Using the Fig.2, the values of the coefficients g
i
can
be determined.
Fig. 2.
Coefficients gi
We have used the equations (7) and (8) to determine the
values of the components of the filters.
0
1
i
cci
CZg
ω
=Ω
(7)
0
i
cci
Z
Lg
ω
=Ω
(8)
III.
DESIGN
AND
SIMULATION
RESULTS
In this paper, a highpass filter having a cutoff frequency 2.5
GHz has been validated, the configuration of the proposed
filter is shown in the Fg.3. The proposed HPF shows a
passband from 2.4 GHz to 7 GHz. In order to validate the
different calculations, the proposed filter has been simulated by
using ADS, it is printed on a low cost FR-4 substrate with a
dielectric constant εr = 4.4, a thickness h=1.6 mm, a loss
tangent tan (δ) = 0.025 and a metal thickness of t=0.035 mm.
The optimized parameters of the proposed filter are
illustrated in TABLE.I.
TABLE I.
D
IMENSION OF THE PROPOSED FILTER
Parameter Value
C(pF) 1.03
L(nH) 2.31
Fig. 3.
Design of proposed filter with localized elements
simulated by ADS
Fig. 4.
S-parameters versus frequency of the proposed filter.
To determine the dimensions of the interdigital capacitor
we have used the equation (1) and the dimensions of the short-
circuited section, we have also used the equations (2-6).
The optimized parameters of the High pass filter with
quasilumped elements are illustrated in TABLE.II.
Authorized licensed use limited to: Universite de Rennes 1. Downloaded on March 20,2023 at 09:30:39 UTC from IEEE Xplore. Restrictions apply.
TABLE II.
D
IMENSION OF THE QUASILUMPED ELEMENTS OF
THE PROPOSED FILTER
Parameter Va lue (mm)
l(C) 4.7
w(C) 0.3
l(L) 3
w(L) 2.2
After many series of optimization and from the dimensions
in TABLE II, we have simulated the design by two identical
interdigital capacitors, and the shunt inductor, we have
obtained the different results shown in Fig.5
Fig. 5.
S parameters versus frequency in GHz.
For s = 0.2 mm, we get a response from a high pass filter,
we notice a good improvement in bandwidth (Fig.6). The
instability in bandwidth is due to the quasilumped elements.
Fig. 6. Design, S-parameters and the bandwidth of proposed filter with
quasilumped elements simulated by CST
In order to verify the simulation results obtained in CST-
MW, we have conducted the same study by using another
electromagnetic solver which is HFSS. We can
see that we
have a HPF behavior with a slight difference which is
due to
the different numerical methods used in these electromagnetic
solvers as shown in Fig.7.
Fig. 7.
A comparison between the simulation results of the
proposed filter under CST and HFSS solver.
Fig. 8.
Current distributions of the proposed filter at (a) at 2.2
GHz and (b) at 3.6 GHz
Fig.8 describes the surface current results of the designed
HPF at 2.2 GHz and 3.6 GHz, the first frequency in the
rejection band and the second one in the bandwidth. As we can
see for 2.2 GHz we have a high attenuation of the signal but for
3.6 GHz the signal passes from port 1 to port2 which validate
the proposed HPF.
IV.
CONCLUSION
In this study, we have validated a planar Compact high-
pass filter based on Quasi-lumped Elements. This proposed
circuit was designed and optimized by using two
electromagnetic solvers ADS and CST Microwave studio and
the results were verified by using HFSS. The proposed filter is
mounted on an FR4 substrate. This HPF is suitable for ISM,
Wimax and Wlan applications.
R
EFERENCES
[1] David M. Pozar, Microwave Engineering, 4th Edition of JohnWiley &
Sons, Inc, 2012.
[2] J.s. Hong and M. J. Lancaster, “Microstrip Filters for RF/Microwave
Applications,” New York: Wiley, 2001.
[3] R. K. Hoffmann, Handbook of Microwave Integrated Circuit, Artech
Hous,1987.
[4] G.M. Yang, R. Jin, J. Geng, X. Huang and G. Xiao, “Ultra-wideband
Bandpass Filter with Hybrid Quasi-lumped Elements and Defected
Ground Structure,” IET Microwave Antennas Propagation, Vol.1, No. 3,
2007, pp. 733-736.
[5] T. Yasuzumi, T. Uwano and O. Hashimoto, “Microstrip High-pass Filter
with Attenuation Poles Using Cross-coupling,” IEEE Asia-Pacific
Microwave Conference, 2010, pp. 107-110.
Authorized licensed use limited to: Universite de Rennes 1. Downloaded on March 20,2023 at 09:30:39 UTC from IEEE Xplore. Restrictions apply.
[6] Performance Comparison of Microstrip High-Pass Filters for Different
Dielectric Substrates. Vivek Singh Kushwah, G.S. Tomar, Sarita Singh
Bhadauria.
[7] Design of 1.5 GHz Quasilumped Microstrip Highpass Filter
Deepak Sharma, Subodh Kumar Singhal, Ram Mehar Singh Dhariwal.
[8] Lumped Elements for RF and Microwave Circuits. Inder Bahl.
[9] J. Jerabek, R. Sotner, J. Dvorak, L. Langhammer and J. Koton,
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[10] S. Parvez, N. Sakib and M. N. Mollah, "Determination of appropriate
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[11]. A novel quasi-lumped UWB high pass filter with multiple transmission
zeros Conference Paper · February 2017
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