I have a G5RV Jr. antenna on a fiberglass mast at 10m height. The only metal on the mast is a 1/8" thick steel guy ring with stainless steel snap links, plus a few small metal screws. Hanging freely, the twin lead on the G5RV Jr. is about six inches away from the guy ring and snap links. (The guy ring is also about three feet from the feed point for the antenna elements, which are in an inverted V configuration.) Can I expect any significant negative effects (i.e. impact on SWR or RF in the shack) from that one guy ring? Thanks.
For the wavelengths (10m upwards) that antenna operates on, small metal objects shouldn't matter significantly.
If anything, they just change the antenna impedance ever so slightly. But since that antenna needs to be used with a tuner anyways, that's not even a downside.