BA4JPR The antenna you made is a 70cm band antenna, and according to many experienced users' diagrams, it needs to be accurate to within 0.01mm, for example:
Now, let's take a look at your antenna:
- The large butterfly has a velocity of approximately 0.02λ, which definitely has an impact. I recommend using the top wire.
- The diameter and position of the resonator must be accurate, at least to the mm level. All through-holes should be on a single line, and the through-holes should not pass through the center (the D2 appears to be significantly misaligned).
- Your parasitic unit（D/RE）Is it just a shell?
- Does the test environment strive to provide a clean, close-range environment? At the very least, it should be an open area; indoor testing is highly inappropriate.
- Is the VNA accurate?
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