Journal of Electromagnetic Analysis and Applications, 2012, 4, 423-425
http://dx.doi.org/10.4236/jemaa.2012.410058 Published Online October 2012 (http://www.SciRP.org/journal/jemaa) 423
Effect of the Width of the NRD Waveguide on the S
Parameter of a Pass Band Filter
Harizi Hanen1, Lattrach Lassaad1, Gharssallah Ali1, Garbi Abdelhafedh2
1Unit of Research Circuits and Electronics Systems High Frequency, Faculty of Science, University El Manar, Tunis, Tunisia;
2Laboratory of Research Circuits and Electronics Systems High Frequency, Faculty of Science, University El Manar, Tunis, Tunisia.
Received July 9th, 2012; revised August 18th, 2012; accepted September 3rd, 2012
ABSTRACT
In this paper, we present a design of a non-radiative dielectric waveguide band pass filter based on hybrid architecture
of micro-strip line and non-radiative dielectric waveguide. The simulation with high frequency structure simulator
(HFSS) three dimensional analyses are presented, also the influence of the feeding transitions for circuit design is studied .
The aim of this work was to study the influence of the width of the NRD waveguide to scattering parameters.
Keywords: Non Radiative Dielectric (NRD)
1. Introduction
The technology demand to realize high efficiency circuit,
but productions cost extremely high. Designed for milli-
metre wave, active circuits use planar technology and
passive circuits employ waveguide technologies to inte-
ger those two technologies require highly accurate as-
sembly thus increasing production cost and time. To de-
crease it, the non radiative dielectric waveguide technol-
ogy should be used.
A non-radiative dielectric waveguide is currently in-
teresting filter types due to their high Q at low cost tech-
nology for fabrication and compatibility with other tech-
nology.
Hence their electromagnetic models are still under re-
search and therefore not easy accessible. This work aims
to provide circuit designers with accurate, easy deter-
minable for a pass band filter.
Proposed by Yoneyama and Nishida in 1981 [1], non-
radiative dielectric (NRD) waveguide circuits is nowa-
days a well-known technology for various millimeter-
wave applications [2,3]. Subsequently, Bacha has pro-
posed the model of a hybrid integration of NRD-
waveguide and micro-strip line [4,5]. Indeed, basic fea-
tures and applications of the NRD-waveguide had been
investigated by different research, since it permits to ex-
ploit inherent advantages of planar structures and NRD
waveguide for low cost microwave application. However,
several techniques wer e proposed, Grigoropoulos and Young
present a non-radiative perforated dielectric (NRPD) in
[6], Cassivi and Wu introduce the substrate integrated
non-radiative dielectric (SINRD) [7]. Other scheme of
design called engraved non-radiative dielectric waveguide
(ENRD), proposed to reduce the problem of alignment
and mechanical tolerances in fabrication of NRD com-
ponents, this design was described in [8,9].
The reference [10] presents the design of pass band
filter in hybrid architecture planar/non radiative dielectric
wave guide integration technology and shows parameters
S. In order to optimize the results of this work, we
thought to var y the width of the N RD gu id e and show th e
influence of this variation.
2. Theoretical Approach
Its basic component, the NRD waveguide consists of a
rectangular-section dielectric rod sandwiched between
conducting plates that are at a distance apart less than
half the free-space wavelength, the thickness is b and the
relative dielectric constant is r

which must be superior
to the relative dielectric constant of the border dielec-
tric.
To express the principle of operation mathematically,
we will consider a straight strip as shown in Figure 1;
the required distance between the two metallic plates of
NRD wave guide is computed using the following rela-
tion:
0
2r
a



where 0

the free-space wavelength r

the relative
dielectric constant.

Effect of the Width of the NRD Waveguide on the S Parameter of a Pass Band Filter
424
3. Results and Discussion
The hybrid architecture planar/NRD waveguide integra-
tion geometry consist of a micro strip line deposited on
the top of ground plane which is one of the two parallel
metallic plates of the NRD wave guide. The coupling
between the two dissimilar structures is achieved though
apertures that are made in the common ground plane.
The aperture orientation defines essentially the operating
mode in the NRD wave guide.
The proposed structure of a design of pass band filter
in hybrid architecture planar/NRD is presented in Figure
2. The filter is composed of a series of cylindrical dielec-
tric resonators with a ray 2b and a height a, coupled
by air gaps of length d.
The micro strip line is made of Rogers RT/Duroid
5880 dielectric substrate with 2.3
r

 and thickness h =
0.508 mm and the strip width of w = 1.55 mm. The slot
size have a length l = 6 mm and a width ws = 1 mm.
The characteristic of the cylindrical dielectrical NRD
wave guide the ray its equal to 4.907 mm and the height
a = 5.08 mm, this cylindrical NRD waveguide is made of
Rogers TMM-3 dielectric substrate 3.27
r

. The pa-
rameters ls = 1 mm and lw = 4 mm.
An absorbing boundary condition is applied in reduc-
ing our computional window for this unbounded struc-
ture so an electrical rectangular box is simulated (Figure
3).
Figure 4 shows the results for a variation of plus or
minus 0.025 mm of the width of the waveguide. The
Figure 1. General structure of NRD waveguide and the dis-
tribution of the electric and magnetic fie lds.
Figure 2. Structure design of cylindrical NRD waveguide.
Figure 3. Dimension design for simulation.
(a)
(b)
Figure 4. Sensitivity of width of the NRD waveguide: (a)
Transmission coefficient; (b) Reflexion coefficient.
variation of the amplitude of the transmission and re-
flexion coefficients, but the adaptation of filter is not in-
fluenced by this variation of the width.

Effect of the Width of the NRD Waveguide on the S Parameter of a Pass Band Filter
425
4. Conclusion
We have presented the design of pass band filter in hy-
brid architecture planar/non radiative dielectric wave
guide integration technology and the influence of the va-
riation of the width of the NRD waveguide to the pa-
rameters S.
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