Alexis
The only time I have seen a similar wide vswr bandwidth with a vector style antenna is when using very lossy coax,
I got lucky with my Vector 4000 install but they can be prone to cmc like any j-pole type antenna compared to a 5/8 with proper radials,
having it connected to a switch that the other antennas are connected to means its possible current could be flowing in any or all coax & antennas connected to the box,
even when using a choke its still possible, a reactive choke can make cmc worse if you are unlucky & it resonates one of the common mode paths,
Vectors can be sensitive to changes in height above ground & mast length if you tune close to ground then raise them higher up,
placing one over a reinforced concrete roof could upset it too,
I run coax from the radio to my antennas & if that means having to unscrew the coax to swap antennas or to swap to another socket on the radio for a different band that's what I do, no switch boxes duplers/diplexers,
no measuring vswr through switches, amplifiers, duplexers/diplexers or anything that adds impedance discontinuities & reactance,
every antenna switch for CB or Ham radio I ever opened up including ALPHA switches are garbage inside or use regular relays.
My radio buddies think I am OCD about it all, which is true, once you go down the rabbit hole there's no turning back,
I think they just like wasting money on things to put inline with their coax so they can sit back & be lazy,
it gives them more time to talk about why their vswr is not right & how they can't hear the guy IM talking to & how noisy their RX is.
