Luneberg Lens Antenna Illuminated by Corrugated HornLenses are used to collimate incident energy to prevent
it from spreading in undesired directions.
Luneberg lenses are broadband. These kinds of lenses
are usually used in microwave frequencies. They areused in antenna constructions, radar calibrations,satellite systems and they are expected to be used infuture in some of the internet communication systems.
Corrugated horn antennas are a type of horn antennas
developed for achieving high efficiency. Horn antennas
are used in satellite systems, radar applications, etc. andare the main type of feeders of reflector and lensantennas.

Theoretical Background
Luneberg lens is a spherically symmetric structure withvariable refracting index, decreases radially out fromthe center. Luneberg lens creates two conjugate focioutside of the lens. Each point on the surface of an ideal
Luneberg lens is the focal point for parallel radiation
incident on the opposite side.

Figure 1. Luneberg lens and corrugated horn antenna

Placing grooves on the walls of a horn antenna is
implemented so that the same boundary conditions toall polarizations are achieved and that the field
distribution is tapered at the aperture in all the planes.
Same boundary conditions eliminate the spurious
diffractions at the edges of the aperture.
Main characteristics of Luneberg lenses are•Broad band,•

Dielectric lens influences the signal transition.

WIPL-D Simulation
An antenna model which consists of a Luneberg lensandacorrugatedhorn,
simulatedusing
WIPL-D Pro 3D EM solver, is presented here. Fullmodel is shown in Fig. 1. Quarter model, wheredielectric layers can be clearly seen, is shown in Fig. 2.
The variable refracting index is approximated by using
five layers of dielectrics with different electricalproperties. The corrugated horn model is shown in
Fig. 3.

Figure 2. Quarter model of Luneberg lens and corrugatedhorn antenna

Our aim is to inspect simulation times and memory
requirements, radiation pattern and near field at theoperating frequency.
Operating frequency is 1414 MHz (D band – NATOband classification).

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Figure 5. Radiation pattern in phi-cut
Figure 3. Corrugated horn antenna

Radiation pattern in 3D and a phi-cut are given in
Figs 4-5, respectively. The diagram shows relatively
high directivity and low side-lobes, as expected. Please
note that the theta angle is measured with respect to thexOy plane.
Distribution of the near field is shown in Fig. 6. The
focusing effect of the lens is clearly seen where aspherical EM wave comes into the lens originatingfrom the horn while on the other side it is transformed
into a plane wave.

Figure 6. Near field

Number of unknowns and simulation time are given inTab. 1. Computer used for these calculations is Intel®
Core2 Quad CPU @ 2.83 GHz, 8 GB RAM.
Table 1. Analysis characteristics

Number ofunknowns

Time [sec]

17174

256

Conclusion
Figure 4. 3D radiation patternThis kind of antenna is usually very difficult for
simulation
usingarigorous
computational
electromagnetics code. However, WIPL-D Pro
successfully analyses the antenna using MoM thanks tosophisticated techniques such as higher order basis
functions. Simulation times are very short comparing toother computational methods of similar accuracy. Thismakes WIPL-D Pro an excellent tool for tackling very
challenging lens antenna designs.
Results given here by WIPL-D Pro coincide withtheoretical expectations.

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