This document summarizes a research paper published in the International Journal of Electronics and Communication Engineering Research and Development. The paper describes the design of a dual-frequency O-shaped 3-way Bagley power divider. A transmission line transformer is used to achieve equal power splitting at 1 GHz and 2 GHz. The design is simulated and tested, with good agreement between simulation and measurement results. Measurements showed input port matching of -35dB and -30dB at 1GHz and 2GHz respectively, and transmission responses close to the theoretical -4.77dB value. The divider was fabricated on an FR-4 substrate using standard PCB fabrication techniques.

1. International Journal of Electronics and Communication Engineering Research and Development (IJECERD),
International Journal of Electronics and Communication Engineering
ISSN 2248-9525(Print), ISSN- 2248-9533 ISSN 2248– 9525 (Print)
ISSN 2248 –9533 (Online), Volume 3, Number 1
IJECERD
Research and Development (IJECERD), (Online) Volume 3, Number 1, Jan-March (2013)
Jan- March (2013), pp.22- 28
© PRJ Publication, http://www.prjpublication.com/IJECERD.asp
© PRJ PUBLICATION
DUAL-FREQUENCY O-SHAPED 3-WAY BAGLEY POWER DIVIDER
BASED ON TLT
Prashant Gupta1, P.K.Singhal2
1,2
Electronics Department, Madhav Institute of Technology and Science,
Gwalior-474005, India
ABSTRACT
In this paper, dual-frequency O-shaped 3-way Bagley power divider is designed and
analysed. Equal split power division is achieved at arbitrary design Frequencies. In this
structure, two-section transmission line transformer is used to realize the dual-frequency
operation. This paper describes a new Bagley power divider on a single-layer micro strip line
that can reduce the occupied area. To validate the design procedure, O-shaped Bagley power
divider is designed, simulated, and fabricated. The design frequencies are chosen to be 1 GHz
and 2 GHz. Very good matching at the input port is achieved, and Good transmission
parameters are obtained from these experiments. The results demonstrate that the design can
fulfil our goals.
Keyword-Bagley power divider (BPD), Microwave wireless application, Full wave simulator
[IE3d], Ms Paint, Ms Excel, Transmission line transformer (TLT), Wilkinson power divider
(WPD).
INTRODUCTION
With the advent of new wireless communication technologies, multi-frequency microwave
components are widely needed. In this regard, multi-frequency transmission line transformers
(TLTs) have been reported in literature [1-6]. In [1, 5], closed form design equations for the
dual-frequency TLT were presented. Tri-frequency and quad-frequency TLTs were reported
in [2, 3], respectively. Furthermore, the general design of multi-frequency TLTs for arbitrary
number of operating frequencies was presented in [4]. On the other hand, other dual-
frequency TLTs for arbitrary number of operating frequencies was presented in [5, 6].The
Wilkinson power divider (WPD) is one of the devices that have taken advantage from the
multi-frequency TLTs in microwave components design. In [7], the design of dual-frequency
unequal split WPD using Monzon's equations [1] was presented. In [8, 9], triple and quad-
frequency equal split WPDs were designed and investigated. The general design of multi-
frequency equal split WPD was presented in [10]. Moreover, the dual-frequency operation is
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2. International Journal of Electronics and Communication Engineering Research and Development (IJECERD),
ISSN 2248-9525(Print), ISSN- 2248-9533 (Online) Volume 3, Number 1, Jan-March (2013)
achieved using three different techniques; namely dual-frequency TLT [1,5]. The design
procedure is simple and straightforward. After reducing the 3-way BPD to its equivalent
circuit model, one of the dual-frequency matching networks can be used instead of the
quarter-wave section to generate the dual-frequency operation of the BPD. Following the
same procedure, triple and quad frequency operation can be achieved by utilizing the triple
and quad TLTs [2, 3]. The designed dual-frequency dividers are simulated using full-wave
simulator (IE3D [11]). Moreover, fabrication and measurement are performed. The results of
the simulations and the measurements are in good agreement.
PROPOSED CONFIGURATION AND THE THEORY
As mentioned above, based on the conventional Bagley polygon power divider,
compact modified Bagley dividers were proposed in [5, 6]. Figure 1(a) shows the schematic
diagram of the 3-way modified BPD [5]. Noting that this divider is symmetric around its
centre line, an equivalent circuit (looking from Port 1 to the right or left side) can be drawn as
shown in Figure 1(b).
Figure: 1 (a)
Figure: 1 (b)
Figure 1 Proposed structure of 3-way BPD.
Referring to the equivalent circuit it can be easily realized that choosing Zh = 2Z0
makes the design of this BPD independent of the length lh. In this case, the characteristic
ଶ୞
impedance (Zm) of the quarter wave section is Zm =ඥሺ2Z଴ ሻ Z୪ , where Z୪ = బ . This gives:
ଷ
ଶ୞బ
√ଷ
Zm =
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3. International Journal of Electronics and Communication Engineering Research and Development (IJECERD),
ISSN 2248-9525(Print), ISSN- 2248-9533 (Online) Volume 3, Number 1, Jan-March (2013)
ଶ୞
Thus, each quarter-wave section matches an impedance of ଷబ to2Z0, resulting in a perfect
match at port 1 (the input port) and equal split power division to the three output ports. As
noted in the Introduction, the BPD does not contain any lumped elements, and it can be easily
extended to any (odd) number of output ports.
DUAL-FREQUENCY MATCHING NETWORKS
Figure shows a schematic diagram for the dual-frequency two-section transmission line
transformer (TLT) [1, 5]. To achieve a dual-frequency operation, the conventional quarter-
wave section is replaced by two transmission line sections, as shown in Figure 2.
Figure: 2. Dual-frequency two-section TLT
The characteristic impedances (Zm1, Zm2) and the line lengths (lm1, lm2) for the two
sections can be evaluated using the following equations [1- 5].
lm1 = lm2 (1)
஠
lm2=ஒଵାஒଶ (2)
α ൌ ሺtanሺβ1lm1ሻሻଶ (3)
୞୬ሺ୞ౢ ି୞୬ሻ ଶ
Zm1 ൌ ඨ ൅ ටZ୬ Z୪ ൅ ቂ
୞୬ሺ୞ౢ ି୞୬ሻ
ଶ஑
ଷ
ଶ஑
ቃ (4)
୞ౢ୞୬
Z୫ଶ ൌ
୞ౣభ
(5)
Where β1 and β2 are the phase constants at the design frequencies f1 and f2, respectively.In
ଶ୞
the case of the 3-way BPD, Zn corresponds to 2Z0, while Z୪ = ଷబ, where Z0 is the ports'
impedance (usually 50 ).
Based on the dual-frequency matching networks presented in the previous section,
dual-frequencies BPD operating at 1 GHz and 2 GHz are designed, simulated, and fabricated.
First, circuit models of the designed dual-frequency O-shaped 3-way BPD is simulated using
the full-wave simulator IE3D [11]. An FR-4 substrate, with a relative permittivity of ୰ = 4.4 ɛ
impedance Z଴ is chosen to be
and a substrate height of h =1.6mm is used. In this design presented below, the terminating
50 which gives Z୦ = 100 and W୦ = 0.64 mm; while, l୦ is chosen arbitrarily.
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4. International Journal of Electronics and Communication Engineering Research and Development (IJECERD),
ISSN 2248-9525(Print), ISSN- 2248-9533 (Online) Volume 3, Number 1, Jan-March (2013)
Figure: 3.The layout of the proposed dual-frequency O shaped 3-way Bagley power divider.
(Dimensions are in mm)
found to be: Z୫ଵ ൌ 69.05Ω and Z୫ଶ ൌ 48.27Ω . The corresponding micro strip line widths
Using the design Equations (4) and (5), the dual-frequency two-section TLT impedances are
considering the substrate mentioned above are W୫ଵ ൌ1.6mm and W୫ଶ ൌ 3.11 mm. From
Equations (2) and (3), the corresponding physical lengths are lm1 = 27.59mm and lm2 =
26.84 mm. Figure 3 represents the layout of the designed dual-frequency 3-way BPD using
TLT sections.
III FABRICATION, SIMULATION AND MEASUREMENT SETUP
The 3-way O-shaped BPD structures are simulated using the full wave simulator IE3D [11].
Figure 4 presents the simulation and measurement results of this dual-frequency 3- way BPD
using TLT. Dual-frequency operation with centre frequencies around 1 GHz and 2 GHz is
clearly seen. As shown in Figure 4(a), good input port matching is achieved with parameter
S11 equals -35 dB and -30 dB at 1GHz and 2GHz,respectively, Figures 4(b),4(b) and 4(c)
show the transmission parameters (S12, S13 and s14). Since the BPD is an equal split power
divider, the simulated and measured values of transmission parameter are close to the
theoretical value of -4.77 dB at the design frequencies. The small differences are due to
losses and discontinuities shown in Figure 4. It is worth mentioning here that because of the
symmetry of the structure, S14 is the same as S12. The agreement between simulated and
measured results can be clearly seen.
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5. International Journal of Electronics and Communication Engineering Research and Development (IJECERD),
ISSN 2248-9525(Print), ISSN- 2248-9533 (Online) Volume 3, Number 1, Jan-March (2013)
Figure: 4(a) Figure :4(c)
Figure: 4(b) Figure: 4(d)
Figure: 4. Simulation and measurement results of this dual-frequency 3- way BPD using
TLT. (Source: IE3D, Ms Excel)
A picture of the fabricated dual-frequency 3- way BPD is shown in Figure 5. An extra 5mm
feeding lines were used at each port of the 3-way BPD to make it possible to attach the BNC
connectors that adapt to the coaxial cables connecting to the spectrum analyzer, when
measurements were performed. The dual-frequency BPD, presented above, have been
fabricated using the same FR-4 substrate, mentioned earlier, and tested using a Spectrum
Analyser extending from 0 to3 GHz.
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6. International Journal of Electronics and Communication Engineering Research and Development (IJECERD),
ISSN 2248-9525(Print), ISSN- 2248-9533 (Online) Volume 3, Number 1, Jan-March (2013)
Figure: 5. a photograph of dual-frequency O-shaped 3-way Bagley power divider
CONCLUSION
Dual-frequency matching network was investigated and applied in the design of dual-
frequency O shaped 3-way Bagley power dividers. Dual-frequency operation was achieved
using two sections of TLT. The full-wave simulation IE3D results and the experimental
results confirmed the dual-frequency operation of the designed divider. Very good input Port
matching and transmission responses were obtained at the design frequencies. Differences
between the simulations and measurements results could be due to the fabrication process,
and measurements Errors. Even though a 3-way BPD was only considered in this paper, the
same procedure can be applied on BPD with any (odd) number of output ports.
ACKNOWLEDGEMENT
I Prashant Gupta student of ME final year Electronics Department, Madhav Institute of
Technology and Science, Gwalior-474005, India designed the proposed structure. This work
is supported by Dr P.K.Singhal Associate Professor Electronics Department, Madhav
Institute of Technology and Science, Gwalior-474005, India.
REFERENCES
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ISSN 2248-9525(Print), ISSN- 2248-9533 (Online) Volume 3, Number 1, Jan-March (2013)
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