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Rectangular horn antenna is one of the
simplest and most widely used antennas. Horns have been used for more
than a hundred years, and today they used in radio astronomy, satellite
communications, in communication dishes as feeders, in measurements,
etc.
The main characteristic of the rectangular horn antenna presented here
is its approximately 20 dB gain. Horn antenna can be considered as an
especially designed waveguide extension. The most important parameters
for operation of this antenna are shown in Fig. 1. These parameters are:
• Length of antenna (determined by Lhorn)
• Width of aperture (determined by a2 and b2)
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Figure 1. Rectangular horn |
Figure 2. Quarter of a
rectangular horn |
WIPL-D Simulation
In WIPL-D Pro, horn antenna given in Fig. 1, can be modeled in a very
simple way, by using several basic building blocks. One can use the
Symmetry feature in both electric and magnetic plane, so only half or
quarter of given antenna can be modeled (Fig. 2), depending on the type
of feeding. Antenna is considered to be surrounded by vacuum, i.e. it is
located in free-space.
For parameters given in Tab. 1, we will calculate gain, near field and
we will compare analysis characteristics for different models of antenna
(with and without Symmetry feature). Computer used for these calculations is Intel Core2 Quad, 2.83 GHz clock.
Dimensions of the rectangular horn model are given in Tab. 1. Operating
frequency is 10 GHz.
Radiation pattern is shown in Fig. 3 and
its phi-cut, where phi=0 (antenna is placed along x axis) is shown in
Fig. 4. Please note that the theta angle is measured with respect to the
xOy plane.
Calculated near field is shown in Fig. 5.
It illustrates the radiation mechanism of the horn.
Numbers of unknowns, memory requirements,
and simulation time are given in Tab. 2.
Table 1. Parameters of
analysis
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Figure 3. Radiation pattern
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Figure 4. Radiation pattern,
phi-cut
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Figure 5. Near field |
Table 2. Simulation data
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Model |
No. of unknowns (memory [MB]) |
Time @ 10 GHz [sec] |
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quarter |
658 (3.5) |
1 |
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half |
1265 (12.8) |
1 |
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full |
2478 (49.2) |
2 |
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Conclusion
The rectangular horn antenna is one of the simplest antennas for EM
modeling and simulation. However, some simulation tools use
computational methods that require relatively long time (several
minutes) to produce results even for the simplest horn models. WIPL-D
Pro provides simulation results swiftly in a matter of seconds rather
than minutes, demonstrating that higher order MoM makes a difference
comparing to other methods even on the simplest examples, not just the
electrically large structures.
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