4.3 Yagi antennaMatlab programIn this layer, we present a user's guide to the program for the analysis of Yagi antenna (the programmer's guide can be found in the layer D). The program is started by entering Yagi_Gui_Master
to the command window of Matlab (path is set to folder Yagi). Menu items of the main form are of the following meaning:
Wavelength | wavelength of the supplying voltage; |
Radius | radius of the wire of antenna elements; |
Reflector length | length of the whole reflector; |
Reflector-dipole | distance between the reflector and the active dipole; |
Number of elements | the number of segments to which the reflector is going to be divided (odd number required); |
Difference 1 | the number of segments for which the active element is shorter than the reflector; |
Difference 2 | the number of segments for which the directors are shorter than the reflector; |
Input element | index of the feeding segment of the active dipole in the complete current vector
(an information item, which cannot be edited); |
Number of elements | the total number of antenna elements; |
Dipole-director | the distance between the active dipole and the nearest director; |
Director-director | the distance between two neighboring directors; |
Dipole length | the length of the active dipole (an information item, which cannot be edited); |
Director lengths | the length of all the directors (an information item, which cannot be edited). |
Pressing the button OK
on the main form, the computation is started. Respective charts
(current distribution, directivity pattern) are sequentially displayed in a single form
after pressing the key Enter.
Pressing the button Apply
on the main form, information items display values of real lengths
(recomputed from the number of segments) of the active dipole and directors, and the value of
the index of the excitation segment. If needed, the number of segments of antenna elements can
be changed before starting the computations.
Pressing the button Cancel
on the main form, the program is terminated.
When the computations are finished, the actual
value of input impedance is printed in the header of the main form. In charts
of directivity patterns, the angle 270° corresponds to the direction from the
dipole to the directors, the angle 90° corresponds to the direction from the
dipole to the reflector.
Since the graphic interface of the program does not support the
setting of individual distances among directors, a more general function
Yagi_Antenna has to be used as a
stand-alone program. for this purpose. When this m-function is started, parameters N
and feed
have to be given (their meaning is explained in the layer D).
The m-function returns the input impedance of the antenna. Further
parameters can be changed in the source code of the function. Individual distances among antenna
elements are set indirectly changing their coordinates with respect to the active dipole (the
positive orientation goes from the dipole to the reflector). Respective charts (current
distribution, directivity pattern) are sequentially displayed in a single form after pressing
the key Enter.
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