Plain-language answer: A vertical antenna is a radiator whose intended dominant electric field is vertically polarized.
Why it changes the result
It can favor low-angle coverage and broad azimuth response, but shortening, loading, return loss, ground, and nearby metal change efficiency and pattern.
What to verify
Use the documented radiator, base, return system, support, and feed line; tune only after final placement.
The common mistake
Assuming every upright whip is efficient and omnidirectional.
Complete-system boundary
Match the exact radiator, feed system, return path, frequency, height, orientation, and environment. Connector or thread fit does not establish electrical compatibility, structural capacity, or safe operation.
