8

If nothing about the physical situation changes, then the SWR will not change. But something might change in the long run, perhaps: Damage to the feed line (water intrusion, sun damage to insulation, chewing by small animals, etc.) Damage to the antenna (corroded junctions, parts broken off, wire fatigue). Plants growing near or on the antenna. Your ...


6

The NanoVNA isn't exactly precision equipment, and the Linx datasheet specifies a maximum VSWR of 2.3, so it's possible the antenna is within spec (barely). You could double-check your calibration by attaching a 50 ohm load and running a sweep: you should see a 1:1 VSWR at every frequency. Of course, if you use the same 50 ohm load you used in the ...


6

Most probably the discrepancy is caused by lack of ground: surface or radials. The coax and/or the VNA are no good ground and the impedance of this counterpoise adds up to the total antenna impedance.


5

In addition to Phil's excellent answer, these specifications are in an "ideal" free space. Having your NanoVNA in close proximity to the antenna (even having the antenna lying on a wooden desk) will influence your measurements. Try just moving it around, closer or farther from other objects, you'll see your results changing. These measurements are ...


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