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So I started writing an antenna simulator program to design antennas for my needs. To calculate the electric field vector at every point, I split the active element of the antenna into a large number of smaller parts and the calculate the electric field generated by each element at that point - taking into account speed of light. In the program I simulated a dipole antenna and it worked well.

Now I'm thinking how could I add support for passive element? If I would like to simulate a yagi-uda antenna, I need to somehow take into account a passive element which does not fit into my model.

Mike Waters
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atomd
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1 Answers1

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Without any insight into the design of your program, I can only offer some basic guidance.

The parasitic elements in a yagi design are shorted dipoles that can also be modeled as a collection of infinitesimal dipoles. A shorted dipole will re-radiate nearly all of the power that it intercepts. This re-radiation will interact with the driven element. The conditions of this interaction depend upon the relative spacial phase separation of the parasitic element from the driven element (and other elements).

The parasitic elements are also slightly shortened or lengthened compared to their resonant frequency. This is done so that the current to voltage phase relationship of the elements simulate the progressive spacial phase shift of a plane wave intercepting, or emanating from, the yagi antenna.

I would think you would find it beneficial to first understand the details of the design theory of a yagi type antenna. There are many references in text books on this subject as well as Internet resources. Here is one of many credible Internet sources.

Glenn W9IQ
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