Vivaldi Antenna
The conventional Vivaldi antenna typically has at leastoctave bandwidth and thus it can be used in many
applications. Vivaldi antenna is placed on dielectric
substrate and because of its complex shape and size, it
is considered to be not so easy for modeling andsimulation.

Because of complex geometry, full explanation ofantenna model is appropriate here, so we add Figs 2-3
to show dimensions and shape of the antenna from bothsides.

Antenna shown here is a balanced antipodal antenna
which consists of a microstrip line and its ground plane
which both gradually flare out. Thus, the lower
operating band limit is determined by the cut-off
mechanism of the flare. The skew in the electric field
across the slot makes poor cross-polar polarization
performance which degrades with frequency rising.
Antenna is considered as triplate based structure. Thatis done by adding additional dielectric and metallization
layer, which is provided for balancing the E-field
distribution in the flared slot. The configuration ofantenna uses arcs and elliptically tapered geometrywhat is serious test for some software in terms ofproviding accurate meshing and far field results.

Figure 2. Vivaldi antenna, dimensions

In November 2000, presented antenna was used for EM
solver comparison, when six software vendors took partin benchmarking. Although WIPL-D didn’t take part in
the benchmarking, we will show here that it thesoftware is capable for designing and simulating thisVivaldi antenna.
Main characteristics of Vivaldi antenna are•

Broad band,•

Dielectrictransition.

substrate

influenceon

signalThe picture of Vivaldi antenna with flared slot aperture(taken from the 2000 benchmark) is shown in Fig. 1.

Figure 3. Dimensions and explanations of Vivaldi antenna

Figure 1. Vivaldi antenna

Our aim is to inspect S11 parameter from 1 GHz up to20 GHz, radiation pattern and near field for two
operating frequencies. Also, we will see what is thesimulation time, i.e. how long do we need to simulate
this model in entire frequency range. For near field andradiation pattern, frequencies 3 GHz and 15 GHz will
be used.

www.wipl-d.com
contactus@wipl-d.com

WIPL-D Simulation
The model of Vivaldi antenna designed and simulatedusing WIPL-D Pro is shown in Fig. 4. The antenna(blue) is printed on dielectric substrate (red). Dielectricused has permittivity of 2.32 and height of 3.15 mm.

Figure 7. Radiation pattern at 15 GHz

Figure 4. Vivaldi antenna model in WIPL-D Pro

Computer used for these calculations is Intel® Core2
Quad CPU @ 2.83 GHz. Memory requirements andsimulation times are given in Tab. 1.

Figure 8. Near field at 3 GHz

Parameter S11 is shown on Fig. 5.

Figure 9. Near field at 15 GHz
Figure 5. S11 parameter for Vivaldi antenna

Radiation patterns and distribution of near field for
3 GHz and 15 GHz are given on Figs 6-9.

Table 1. Simulation characteristics

Model

Number ofunknowns

Memory[MB]Time [sec]

3 GHz

3160

80

217

15 GHz

17339

2400

1344

Conclusion
WIPL-D Pro offers very efficient simulation of aVivaldi antenna.
Figure 6. Radiation pattern at 3 GHz

Results given by WIPL-D Pro, presented here, coincidewith theoretical expectations, and agree well with theresults presented by most other software vendors in thesoftware benchmark published in 2000.

www.wipl-d.com
contactus@wipl-d.com