COAXIAL ANTENNA SIMULATION

A coaxial antenna is a vertically polarized omni-di-rectional antenna. It was first registered as US patent by Arnold B. Bailey in 1939 as a vertical antenna pro-viding 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. The following example models a basic prototype of coaxial antennas: a quarter-wavelength section of a coaxial cable such that the inner and outer conduc-tors 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.

FIGURE 1: GEOMETRY OF THE COAXIAL ANTENNA

Through this simulation, we should be able to visualize ra-diation patterns of the antenna, calculate the reflection at its port and view its near and far field distribution in 2D and 3D plots between 2 and 4 GHz.

SIMULATION BOUNDARY CONDITIONS

This coaxial antenna has a PEC volume laying along the conduc-tor’s stem. The input port is placed on the Teflon surface between the ground and signal conductors. We assign -as it is usual for antenna studies-, radiation boundaries to the lateral surfaces of the mod-el. In this example, we’re only in-terested in the radiations made in front of the wider circular face.

HFWORKS APPLICATIONS

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 as we can see the dis-tances separating the points from the origin.

FIGURE 2: WAVE PROPAGATION IN THE ANTENNA AT 2 GHZ

This animation shows a capture of the wave propagation inside the co-axial antenna using ths section clipping feature of HFWorks.

FIGURE 3: RADIATION PATTERN OF THE ANTENNA

We might have a rough 3D electric field plot due to a bad choice of chart scale and angles’ steps. so we define the minimum and maximum values and things will get clearer. We can animate the 3D plot by vary-ing its phase to see how changing the omega T phase affects the distribution of the field.

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