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Ultra wide band elliptical (UWB
elliptical) antenna is a type of a printed antenna. It is small, simple,
lightweight and economical, often used in UWB transmitters. UWB antenna
topologies are derived from works in circular and elliptical disc
monopoles. The main characteristic of the given elliptical antenna is
that it is broadband.
WIPL-D Simulation
In WIPL-D Pro, metallic plates are colored in blue and dielectric plates
are colored otherwise, so we see that the given antenna is printed on a
finite dielectric substrate (Fig. 1) and has no ground plane (reflector;
Fig. 2), thus we expect low directivity and high radiation in both front
and back directions. In WIPL-D Pro, this antenna can be modeled in
several ways in order to diminish simulation time and memory
requirements. One can use the Symmetry feature, so only half of the
given antenna is modeled (Fig. 3), thus saving both memory and time.
Antenna is analyzed in frequency band 2 GHz up to 20 GHz.
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Figure 1. UWB elliptical antenna |
Figure 2. UWB elliptical antenna,
bottom side |
We will calculate S11 parameter in the
entire range in order to determine antenna operating band and to analyze
antenna matching, radiation pattern and near field at one frequency at
which antenna is matched. Computer used for these calculations is Intel Core2 Quad @ 2.83 GHz clock.
Parameter S11 is shown in Fig. 4. We can see that antenna operating band
is from 4 GHz up to 14 GHz (where, parameter S11 is roughly less than
-10 dB).
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Figure 3. UWB elliptical antenna
– half model |
Figure 4. Parameter S11 |
Antenna gain in 3D is shown in Fig. 5. We
can see that gain is low (maximum is about 4.5 dB). Also, antenna is
quasi-omni-directional (Fig. 5). Radiation pattern has minimums in four
directions in the xOy plane, which are expected for this antenna design.
Calculated near field is shown in Fig. 6.
We can see the transition from standing EM wave to free space EM wave.
We should notice that only half of the antenna is shown in Fig. 5
because we used model symmetry.
Number of unknowns and simulation time of analysis are given in Tab. 1.
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Figure 5. Radiation pattern in 3D |
Figure 6. Near field |
Table 1. Analysis characteristics
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No. of unknowns |
Time [sec] |
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2787 |
151 |
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Conclusion
WIPL-D Pro is a frequency-domain software and analyzed structure is
broadband (operating from 5 GHz up to 14 GHz). This type of simulation
is usually challenging for frequency-domain solvers and time-domain
solvers usually have much shorter simulation times. However, we can
notice that simulation time in WIPL-D Pro is very short even though it
was done in 21 frequencies, thanks to:
• very small number of unknowns this model requires as a result of
higher order method of moments in combination with Edging technique for
meshing,
• very fast numerical libraries implemented in WIPL-D Pro solver that
use modern CPU architectures to full extent,
• Symmetry option is used in this problem and thus, number of unknowns
is halved and simulation time decreased significantly.
Hence, WIPL-D Pro is probably the only frequency domain solver that can
compete with leading time domain codes in terms of simulation times in
UWB simulation. Results given by WIPL-D Pro and presented here coincide
well with theoretical expectations.
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