Having larger value of VSWR is indication of improper matching. Eg. http://www.abracon.com/patchantenna/ACA-107-T.pdf this datasheet claims VSWR to be around 4:1 to 5:1 (which seems bad VSWR value to me). Also it claims that the antenna is Matched to 50 Ohm. Well, it appears that load impedance (here input impedance of the antenna) should be around 4 to 5 times higher or smaller than that of transmission line impedance in order to achieve this value of VSWR (i.e. either around 200 ohm or 12 ohm for transmission line of 50 ohm characteristic impedance). First question is, if it's such a bad VSWR, why do these manufacturers claim that it is matched with 50 ohm, Second question, are there any impedance converters which can be used to compensate for such improper matching, or should we just use passive RLC networks to correct the mismatch?