Design of LTCC Wideband Patch Antenna for LMDS Band Applications
ABSTRACT This letter presents a wideband patch antenna on a low-temperature cofired ceramic substrate for Local Multipoint Distribution Service band applications. Conventional rectangular patch antennas have a narrow bandwidth. The proposed via-wall structure enhances the electric field coupling between the stacked patches to achieve wideband characteristics. We designed same-side and opposite-side feeding configurations and report on the fabrication of an experimental 28-GHz antenna used to validate the design concept. Measurements correlate well with the simulation results, achieving a 10-dB impedance bandwidth of 25.4% (23.4-30.2 GHz).
- SourceAvailable from: Manuel Arrebola[show abstract] [hide abstract]
ABSTRACT: A two-layer reflectarray is proposed as a central station antenna for a local multipoint distribution system (LMDS) in the 24.5-26.5 GHz band. The antenna produces three independent beams in an alternate linear polarization that are shaped both in azimuth (sectored) and in elevation (squared cosecant). The design process is divided into several stages. First, the positions of the three feeds are established as well as the antenna geometry to produce the three beams in the required directions. Second, the phase distribution on the reflectarray surface, which produces the required beam shaping, is synthesized. Third, the sizes of the printed stacked patches are adjusted so that the phase-shift introduced by them matches the synthesized phase distribution. Finally, the radiation patterns are computed for the central and lateral beams, showing a shaping close to the requirements. A breadboard has been manufactured and measured in an anechoic chamber, showing a good behavior, which validates the designing methodology.IEEE Transactions on Antennas and Propagation 07/2008; · 2.33 Impact Factor
Conference Proceeding: Vertical transitions in low temperature co-fired ceramics for LMDS applications[show abstract] [hide abstract]
ABSTRACT: To realize the advantages of low temperature co-fired ceramics (LTCC), such as highly integrated and low cost microwave packages, a library of repeatable and low loss vertical transitions is necessary. This paper presents measured results of three LTCC vertical transitions: stripline to coplanar waveguide (CPW), CPW to CPW, and CPW to microstrip. A novel grounding structure for intermediate ground planes is presented and discussed. The measured results demonstrate vertical transitions with good performance across the LMDS rangeMicrowave Symposium Digest, 2001 IEEE MTT-S International; 02/2001
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ABSTRACT: A simple procedure for the design of compact stacked-patch antennas is presented based on LTCC multilayer packaging technology. The advantage of this topology is that only one parameter, i.e., the substrate thickness (or equivalently the number of LTCC layers), needs to be adjusted in order to achieve an optimized bandwidth performance. The validity of the new design strategy is verified through applying it to practical compact antenna design for several wireless communication bands, including ISM 2.4-GHz band, IEEE 802.11a 5.8-GHz, and LMDS 28-GHz band. It is shown that a 10-dB return-loss bandwidth of 7% can be achieved for the LTCC (ε<sub>r</sub>=5.6) multilayer structure with a thickness of less than 0.03 wavelengths, which can be realized using a different number of laminated layers for different frequencies (e.g., three layers for the 28-GHz band).IEEE Transactions on Advanced Packaging 12/2004; · 1.12 Impact Factor
IEEE ANTENNAS AND WIRELESS PROPAGATION LETTERS, VOL. 9, 20101111
Design of LTCC Wideband Patch Antenna
for LMDS Band Applications
Kuo-Sheng Chin, Member, IEEE, Ho-Ting Chang, and Jia-An Liu
Abstract—This letter presents a wideband patch antenna on a
low-temperature cofired ceramic substrate for Local Multipoint
Distribution Service band applications. Conventional rectangular
patch antennas have a narrow bandwidth. The proposed via-wall
structure enhances the electric field coupling between the stacked
patches to achieve wideband characteristics. We designed same-
side and opposite-side feeding configurations and report on the
fabrication of an experimental 28-GHz antenna used to validate
the design concept. Measurements correlate well with the simu-
lation results, achieving a 10-dB impedance bandwidth of 25.4%
Index Terms—Local Multipoint Distribution Service (LMDS)
antenna, low-temperature cofired ceramic (LTCC) patch antenna,
stacked patch, via-wall structure, wideband patch antenna.
transmission techniques, which are highly desired in modern
wireless communication applications –. LMDS covers
several bands from 27.5 to 31.225 GHz, requiring antennas to
operate at high frequency with a wide bandwidth of 3.75 GHz
(or 12.8%). These high operating frequency and wide band-
width requirements increase the difficulty of designing LMDS
Patch antennas are an attractive option thanks to their advan-
tages of planar configuration, low profile, easy analysis, and
convenient integration with other microwave circuits. However,
conventional rectangular patch antennas have the disadvantage
of a narrow bandwidth, typically bandwidth
previous studies have focused on the development of wideband
patch antennas –. One approach  used an embedded
air cavity between stacked patches in low-temperature cofired
ceramic (LTCC) devices to reduce the dielectric constant and
quality factor to enhance bandwidth. Lau et al. implemented
a folded feed and cut an L-shaped slot on the folded patch
antenna to create multiple resonant current paths, yielding wide
bandwidth . Zhang et al.  combined a shorted bowtie
dipole and an L-shaped electric dipole fed with
strip to achieve wideband performance in a compact design.
OCAL Multipoint Distribution Service (LMDS) provides
wideband Internet communication using millimeter-wave
Manuscript received September 20, 2010; revised November 17, 2010; ac-
cepted November 17, 2010. Date of publication November 29, 2010; date of
current version December 13, 2010. This work was supported in part by the Na-
tional Science Council, Taiwan (NSC 99-2221-E-182-033), Chang Gung Uni-
versity, Taiwan (UERPD290051), and the High Speed Intelligent Communica-
tion Research Center.
The authors are with the Department of Electronic Engineering, Chang Gung
University, Tao-Yuan 333, Taiwan (e-mail: firstname.lastname@example.org).
Color versions of one or more of the figures in this letter are available online
Digital Object Identifier 10.1109/LAWP.2010.2095406
Fig. 1. LTCC via-wall stacked patch antenna: (a) 3-D schematic structure and
(b) cross-sectional configuration.
Other researchers  have recently presented a wideband
slot-loaded octagon patch capacitively fed by a small rectan-
gular patch for use on cylindrical surfaces. Stacked patches are
often implemented in LTCC antenna design to achieve wide
bandwidth , , –. However, wider bandwidth is also
achievable by applying via walls to the stacked patches.
In this letter, we designed a wideband antenna consisting of
stacked patches and via-wall structures in LTCC for LMDS ap-
plications. The proposed via-wall structure enhances the field
between stacked patches, achieving an increase in bandwidth of
up to 25.4%. Two feeding configurations were designed to draw
dition, we fabricated and measured a prototype to demonstrate
the facility of the design.
II. VIA-WALL STACKED WIDEBAND PATCH ANTENNA
Fig. 1(a) shows the 3-D schematic structure of the proposed
patch antenna, including stacked patches and two via walls
in the LTCC to increase operational bandwidth. This design
uses five metal layers separated by four ceramic layers with
thicknesses of 0.18, 0.18, 0.24, and 0.16 mm, respectively. The
parasitic patch, measuring 3.445
patch (1.8451.78 mm ) were placed on Metal 1 and Metal 4,
respectively. Using stacked patches of different sizes provided
superior bandwidth performance. Fig. 1(b) illustrates the
cross-sectional configuration of Fig. 1(a), in which the via walls
are connected to ground and situated beside the nonradiating
edges of the main patch. When the main patch resonates at the
operating frequency, the two via walls behave like a capacitive
load, enhancing the radiating electric field coupling between
the main patch and parasitic patch to increase the bandwidth.
1.12 mm , and the main
1536-1225/$26.00 © 2010 IEEE
1112IEEE ANTENNAS AND WIRELESS PROPAGATION LETTERS, VOL. 9, 2010
Fig. 2. Equivalent circuit of the proposed via-wall stacked patch antenna.
Fig. 3. Simulated ?
??????? nH, ?
? ? ??? ?, and ? ? ? are assumed).
responses of the equivalent circuit in Fig. 2 (?
? ????? pF, ?
? ?????? nH, ?
?? ????? pF, ?
Fig. 2 shows the equivalent circuit of the proposed antenna in
Fig. 1, in which two parallel
resonance frequencies for the main patch and parasitic patch.
Coupling the main patch to an upper patch makes the circuit re-
sponse more inductive.denotes the magnetic coupling be-
tween the two patches.
represents the capacitive coupling
caused by the shorted via-wall structure, and
inductance of the feed line.
Fig. 3 plots the simulated
cuit in Fig. 2 using AWR’s Microwave Office software with
the assumed parameters listed in the caption of Fig. 3. This
figure shows that the two resonant poles caused by the res-
(main patch) and
can be pulled away using capacitive coupling to achieve wide-
band characteristics. The two poles in Fig. 3 gradually shift
away from each other as the coupling capacitance
from 0.0 to 0.02 pF. Fig. 3 proves that the coupling capaci-
tance enhances impedance bandwidth. The shorted via walls in-
crease the electric field between the patches, making the cir-
cuit response more capacitive. This is the means by which the
proposed via-wall structure increases capacitance
bandwidth. Because the depth of return loss decreases as
creases, it must account for the tradeoffs between the required
bandwidth and return loss performance. Notably, Fig. 3 is used
only to characterize the variance in bandwidth associated with
the capacitive coupling scheme. The accuracy of the antenna
dimensions were finely tuned with the aid of the full-wave elec-
tromagnetic simulator HFSS.
sign parameters, where , , and
eter, and center-to-center distance of the via, respectively.
notes the distance between two via walls, and
dielectric constant of the LTCC material. Constraints in LTCC
fabrication process require that
mm. Fig. 5 shows the bandwidth of the proposed
resonators establish the two
is the parasitic
responses of the equivalent cir-
represent the length, diam-
is the relative
Fig. 4. Via-wall configuration: (a) 3-D schematic structure and (b) top view.
Fig. 5. Bandwidth versus the distance between two via walls, ?, with various
via length ? (? ? ???, ? ? ???? mm, and ? ? ???? mm)
patch antenna versus
that the bandwidth increases as
influence than . However, must be less than 0.58 mm because
the top ceramic layer is reserved for the parasitic patch, which
cannot be shorted to the ground. The curves in Fig. 5 reveal that
mm and mm achieved the widest bandwidth
For performance testing, the embedded feed line and ground
of the patch antennas were required to draw out from inside the
LTCC to the surfaces for a connection. The effect of vertical
interconnection with the cross-layer scheme became noticeable
at higher frequencies. A good vertical interconnection between
input port and the main patch connection is necessary to enable
good signal transmission. Fig. 6 compares two feeding configu-
rations, same-side feeding and opposite-side feeding structures.
In the same-side feeding structure of Fig. 6(a), the feed line and
parasitic patch are situated on the same surface. The upper feed
line connects to the lower feed line with a signal via, and many
ground vias stitched together are placed on both sides to con-
struct a vertical ground–signal–ground structure. To maintain
the 50-impedance, the required line width of the upper feed
line widens as the substrate increases in thickness, which may
cause serious discontinuity. Thus, the ground under the upper
feed line must be raised to reduce the width of the line.
feed line is close to the parasitic patch, disturbing its radiation
pattern. Fig. 6(b) depicts the opposite-side feeding structure,
whichdoesnotelectrically influence theparasitic patch because
they are situated on opposite sides and separated by the ground.
Moreover, the opposite-side feeding structure has a shorter via
length than the same-side feeding structure, reducing the par-
asitic via inductance. The ground above the lower feed line in
Fig. 6(b) was lowered to reduce the width of the lower feed line
with variations in . This figure indicates
increases, andhas a greater
CHIN et al.: DESIGN OF LTCC WIDEBAND PATCH ANTENNA FOR LMDS BAND APPLICATIONS1113
Fig. 6. Proposed patch antennas with feeding configuration: (a) Same-side
feeding structure and (b) opposite-side feeding structure.
Fig. 7. Simulated ?-parameter responses of the opposite-side feeding
and ensure a good interconnection. Fig. 7 shows the simulated
-parameter responses of the opposite-side feeding structure in
which it is treated as a two-port network. The maximum inser-
tionloss andminimumreturnloss at28GHzare
dB, respectively. These are excellent results
for a vertical interconnection operated at such high frequencies.
III. ANTENNA FABRICATION AND MEASURED RESULTS
tennas with same-side feeding and opposite-side feeding struc-
tures were synthesized and fabricated on a LTCC substrate. The
center frequency was set at 28 GHz, and the full-wave elec-
tromagnetic simulator HFSS was used to simulate the antenna.
To keep dielectric losses low, we adopted the LTCC material
system provided by Advanced Ceramic X Corporation with rel-
ative permittivity 7.5 and loss tangent 0.005. All buried, ex-
posed, and filled conductors were silver, and a K (2.92 mm)
end-launch connector was chosen as the input. The results of
better than those obtained from the same-side feeding structure
antenna with the opposite-side feeding structure.
Fig. 9. ??-plane and ??-plane radiation patterns of the experimental antenna
at (a) 23.4, (b) 27, and (c) 30.2 GHz.
due to the low degree of disturbance affecting the patches. For
brevity, this letter only presents the results of antennas with an
opposite-side feeding structure.
The antenna was measured in an anechoic chamber using an
suredresponses. The measured
frequency shifted to 27 GHz with 10-dB impedance bandwidth
showed that the center
1114IEEE ANTENNAS AND WIRELESS PROPAGATION LETTERS, VOL. 9, 2010
Fig. 10. Measured gain curve of the experimental wideband antenna.
Fig. 11. (a) Dimensions, (b) thickness of layers, (c) top-view photograph, and
(d) bottom-view photograph of the fabricated patch antenna.
of 25.4% (23.4–30.2 GHz). These results confirm the effective-
ness of the structure of the proposed circuit. The extra dip in the
at 26.2 GHz was caused by an inadequate con-
nection of the feed line and the K end-launch connector. For
comparison, Fig. 8 plots the corresponding curve of the stacked
patch without the via-wall structure with a very narrow band-
width of only 11%.
Fig. 9 shows the simulated and measured
-plane radiation patterns of the proposed antenna at (a) 23.4,
(b) 27, and (c) 30.2 GHz. Both simulated and measured re-
sponses showed good agreement. Fig. 9(b) shows that the
plane andplane had smooth copolarization patterns with
a 3-dB beamwidthand a gain of 5 dBi at 27 GHz. The
simulated and measured cross-polarization results were better
in the broadside direction. The larger measured cross-polar-
ization is attributed to the defective connection of the feed
line and connector and inaccuracy in both the polarization
and mechanical alignment between the transmitting horn and
experimental antenna. The backside radiation was noticeable,
mainly because of the feed line and the small size of the ground
plane. The radiation patterns at both the high and low band
edges had a low degree of variation compared to the center
frequency, which enabled wideband performance.
Fig. 10 presents the measured gain curve of the antenna
from 23 to 30 GHz, showing that the antenna gain varied
from 4–6.8 dBi over the entire band. These results are quite
acceptable for patch antennas fabricated with cross-layer
interconnections and long feed lines and mounted with
connectors at such high frequencies. Fig. 11(a) and (b) pro-
vides detailed dimensions of the circuit and the thickness
of layers in the antenna. The total size, including the feed,
photographs of the experimental antenna with a K end-launch
connector attached for testing.
mm. Fig. 11(c) and (d) shows
This study designed a wideband patch antenna for LMDS
band applications. The proposed antenna consists of stacked
patches with a via-wall structure in LTCC. Using the via-wall
structure to enhance the electric field coupling between the
stacked patches achieved wideband performance in a compact
size. Two feeding configurations were developed for connec-
tion.The conceptof thedesign was demonstrated byfabricating
an experimental wideband patch antenna that achieved a band-
width of 25.4%.
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