eBay yet again doesn’t disappoint when it comes to fake kit. Here is a claimed dual-band antenna, a Nagoya NA-771. This is supposed to be good for both 144MHz & 433MHz.
The first clue is in the logo printing on the base, it’s not straight, or even. The base isn’t aligned correctly with the connector either, being glued on at a janky angle.
Beyond looks, a network analyser really shows the problems. Here’s a scan from 50MHz to 500MHz. There’s a fairly decent SWR of 2.01:1 at 164MHz (the tuning is still off, it’s supposed to be at 144MHz), but the SWR at 433MHz is 13:1!
Extending the range to 1GHz does show another couple of resonant points, at 544MHz (1.99:1) & 920MHz (2.83:1), well outside the band that this antenna is supposed to work to.
