RLSA

Radial Line Slot Antenna is a planar antenna, a pair of slot antennas are located on a radial line or cocentric lines to be coherent with the phase, which make the radiation concentrate on the bore side of the antenna.

It is well known as a telemetry antenna of Akatsuki, launched for Venus mission by JAXA.

Here, we show a case of simulation by our house-made simulator, Electro Magnetica Numerical.

RLSA model

Figure 1 shows the model we are about to simulate. The number of the slots are 284 and the target frequency is 32GHz.

Figure 1: Bird’s eye view of RLSA model

Figure 2 shows the view of the RLSA antenna. There is a coaxial waveguide port is connected in the other side.

Figure 2: Cross section of the Antenna 

The main purpose of this antenna module is to communicate the far distance from Venus to the Earth. So the directivity is very important. The ideal directivity of the module is expected to be 30.5dB. This would be the upper limit of the module.

 Numerical Analysis

The Top panel, the connector and coaxial waveguide are prepared as CAD data, the simulator imports them as STL files. User specify the signal input port and the impulse signal which is centered with 32GHz. Simulation are performed with these parameters and calculate the response of the antenna in the far field radiation pattern.

Electro Magnetica Numerica can perform the simulation without any struggle on mesh generation. The generation is performed automatically.

Figure 3 shows the snap shot of signal front of the input impulse approaching to the slots on the Top antenna panel.

Figure 3: 同軸導波管から給電された信号波面がスロットに近づいていく様子。

Figure 4 shows the simulated directivity at 32 GHz.

Figure 4: Directivity at 32GHz

Authority of the antenna gives us a comment this is a reasonable value.