Plain-language answer: Front-to-side ratio compares the forward response with response near the side of a directional antenna.
Why it changes the result
It can help reject unwanted signals or noise, but depends on the exact side angle, frequency, and polarization.
What to verify
Use the plotted angles and rotate through the full azimuth instead of checking only front and rear.
The common mistake
Assuming good front-to-back performance guarantees strong side rejection.
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.
