SteppIR BigIR - HOW TO TUNE YOUR VERTICAL (MANDATORY)

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A vertical antenna’s resonant frequency is determined by the length of its radiator, radial(s), soil con-
ductivity, as well as a variety of other factors. Since every installation is different, the factory default lengths in
the controller for each band/frequency are almost guaranteed to be need adjustment for your particular instal-
lation. Because of this, it is mandatory to tune the length of the antenna on all frequencies of operation
before application of high power.
This is done by pressing “Setup” and selecting the “Create/Modify” menu. In this menu, the operator
can adjust the length of the driven element (DVR/DE) until the SWR is at least below 1.4-1.3. An antenna an-
alyzer (Vector Network Analyzer) is extremely helpful for this task as it allows the user to plot SWR over a fre-
quency range, at which you can match the SWR dip in the antenna with the frequency which you are tuning in
the create/modify menu. If you are unable to make a good match by adjusting the length of the driven
element, you most likely have an issue with your connections/radials.
SteppIR antenna tunes are broken up into “segments” which we use to create an ideal antenna at a
specific frequency. Each segment consists of a frequency, element lengths, coil switch command, and some
miscellaneous display settings like gain, F/R, and beam width. To get the element lengths at frequencies in
between segments, the controller utilizes an algorithm to calculate them with the given segment information.
The controller can only “store” lengths at the start of each segment, and it calculates the lengths in between.
What this means for the end user is that the antenna can only be tuned once in between each segment.
Important notes:
• In order to save a setting in the Create/Modify menu, you can simply exit from the screen by pressing
“Setup” again, and when the controller prompts you whether you want to save your changes make sure
you select “Y” to save your changes.
• Adjusting the coil tap position is almost never necessary to get a good match, and if you have to do so,
you most likely have a problem with your radials that is worth addressing.
On the next few pages are lists of the segments, segment frequencies, and recommended tune
frequencies for the BigIR for the SDA100 and OptimizIR controllers.
HOW TO TUNE YOUR VERTICAL (MANDATORY)