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Coaxial Antenna
Description
A coaxial antenna is a vertically polarized omni-directional antenna. It was first registered as US patent by Arnold B. Bailey in 1939 as a vertical antenna providing coaxial element sleeve structures. A new type using radiation by the outside of the coaxial elements was also registered in 2006 by Bonnie Crystal as a coaxial antenna with smaller size and more efficient broadband, wideband and controlled bandwidths. This example models a basic prototype of coaxial antennas: a quarter-wavelength section of a coaxial cable such that the inner and outer conductors are separate but still attached to the remaining cable. This antenna operates between 2 GHz and 4 GHz. In this report, we find further description and plots of the antenna's performances.
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Figure 1 - Geometry of the coaxial antenna
Simulation
Through this Antenna simulation, we should be able to visualize radiation patterns of the antenna, calculate the reflection coefficient at its port and view its near and far field distribution in 2D and 3D plots between 2 and 4 GHz.
Load/ Restraint
This coaxial antenna has a PEC volume laying along the conductor's stem. The input port is placed on the Teflon surface between the ground and signal conductors. We assign, radiation boundaries to the lateral surfacesof the air box.
Results
This chart shows the return loss at the antenna's port for the frequency band from 2 to 4 GHz. We can get the curve smoother by applying a small frequency step; However, the values will have almost the same magnitude : the magnitude of the reflection coefficient is almost the same for this frequency band.
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Figure 2 - Wave propagation in the antenna at 2 GHz
This animation shows a capture of the wave propagation inside the coaxial antenna using the section clipping feature of HFWorks.
Figure 3 - Radiation pattern of the antenna
We might have a rough 3D electric field radiation due to a bad choice of chart scale and/or angles' steps. In this case, we define the minimum and maximum values to have a clearer view.