Quasi Yagi Antenna
Abstract:A planar X-band quasi-Yagi antenna is analyzed with the FEM simulator in EMPro.Planar quasi-Yagi antennas provide broadband performance with good radiation characteristics in a compact form-factor. In this example we create a parameterized 3D model in EMPro based on a design presented in Reference (1). Finite Element Method (FEM) simulations are performed to evaluate the performance. The model includes a coaxial connector so that this is taken into account in the simulated results.
Figure 1: 3D model of quasi-Yagi antenna, including connector, in EMPro
In order to acheive the desired performance across the frequency band of interest, there are several dimensions in the physical antenna design that need to be set properly. For example, the lengths and widths of the stubs will determine the frequency of operation. In EMPro all of the key dimensions were parameterized so that the design could quickly and easily be modified to attain certain performance characteristics, such as operation across the 8-12GHz range with maximum gain at 10GHz.
Figure 2: Antenna design dimensions and parameter table in EMPro
There are several ways to feed the incoming signal to the antenna structure. The approach used in this design is a coplanar waveguide feed, without the use of a balun that is required in some designs (see Reference 1 for more information on this design approach).
Figure 3: Close-up of feed design
The antenna was analyzed using the FEM simulator in EMPro. The results below indicate good performance over the X band.
Figure 4: 3D gain pattern at 10GHz
Figure 5: 2D gain pattern at 10GHz, Theta=90deg (top view)
Figure 6: 2D gain pattern at 10GHz, Phi=90deg (side view)
Figure 7: Return loss vs. frequency
Figure 8: Gain vs. frequency
EMPro can be used to create a fully paramterized 3D model, which makes it fast and easy to develop this quasi-Yagi antenna design. The FEM simulator can quickly analyze the design and validate performance over the X-band operating range.
(1) Kan, Waterhouse, Abbosh, and Bialkowski, "Simple Broadband Planar CPW-Fed Quasi-Yagi Antenna", IEEE Antennas and Wireless Propogation Letters, Vol. 6, 2007