Ultra-wideband antennas are designed for use over a wide frequency range. They are often used to capture signals from different sources without the need to change antennas. These antennas are an ideal choice for applications such as medical imaging, telecommunications, the Internet of Things, detection, etc.
At the same time, it’s important to keep antenna dimensions as small as possible, to facilitate their integration into complex devices. This is a complex challenge in the antenna design process.
This topic presents the design and development of a miniature, broadband spiral cavity antenna. This antenna represents an improvement on existing work in terms of compactness and low frequency of use. Using the advanced features of Ansys HFSS, we were able to design and optimize both the antenna and the feed balun.
The model antenna is a double spiral with a diameter of 14.5 cm. The feed balun (not visible here) is integrated into the cavity. The cavity is designed to eliminate back radiation, which can be problematic for antenna integration.
We study the antenna matching (figure 2) to find out its operating frequency range.
We can see that the antenna operates from 330 MHz up to 1.5 GHz.
Next, we look at the antenna’s radiation pattern. In 3D and in polar.
We can see that the antenna is directional and that back radiation is strongly attenuated.
Finally, we study the axial ratio to ensure the purity of the circular polarization of this antenna:
This antenna is circularly polarized from 340 MHz.
To conclude, we have designed a circularly polarized cavity spiral antenna that operates from 350 MHz and measures 14.5 cm in diameter.
