AN-SOF MPAS-Lite Vertical
This is an AN-SOF antenna model for a Chameleon Antenna MPAS-Lite ground mounted vertical antenna using the CHA 5:1 Hybrid Mini, CHA SS-17 telescoping 17' whip, ground mounted spike, 4 each DIY 25' counterpoise wires, and 50' of RG-58C coaxial feed line. This model assumes average North American ground properties.
This analysis does not call out many of the analysis/setup steps and instead, focuses on the key analysis results needed to understand the top-level performance of the antenna. See the 10m vertical in free space post for a walk through with all the detailed steps called out.
Setup simulation and counterpoise parameters:
Add the vertical element, source, and source location:
Setup the coaxial feedline and hybrid parameters (Note that 0 dB IL for TRAFO is selected):
Run the analysis and look at the VSWR over the frequency range:
The VSWR is over 14:1 down at 7 MHz, decreasing down to and stabilizing at around 3:1 as the frequency increases.
Plots of antenna parameters (note Zin radio button for "Feeder" is selected):
Zoom in on the VSWR plot (Feeder selected):
Chameleon Antenna positions this antenna as broad-band with tuner required. Use during ARRL Field Day 2024 showed good performance over the 7 - 54 MHz bands with the 50' RG-58C feedline and using a LDG Electronics automatic antenna tuner in-line.
This antenna has an omni-directional pattern with low elevation angles. Over the 7 to 29 MHz frequency range, the patterns do not exhibit moding and yield a decreasing elevation angle as the frequency is increased.
Conclusions: This is a reasonable antenna to use when quick setup, broad frequency range, and omini-directional coverage is needed. The antenna is easy to deploy and does not have a lot of visual presence (only a single 17' telescoping whip). No vertical supports or trees are needed for this ground mounted vertical system. An antenna tuner is needed on most bands, with an automatic tuner providing quick frequency changes between bands. This antenna was used at my 2024 ARRL Field Day station and provided lots of contacts when temporarily setup for the weekend.
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