I don't know if this has been discussed but just wanted to share my experience with the Vortech ReRadiator Antenna.
My GPS units do not have the External Antenna plug so this was the only option. (I have a couple Rino 120's and Etrex Legend)
I just installed it in my Montero and WOW. I used to get good coverage with the Etrex mounted using a vent clip mount. But when I plugged the Vortech (Truck in Driveway) in I got 4 more satellites totalling 10, all at max or near max signal! Before the vortech, I had 6 sats withhalf or less reception.
Anyway, I just wanted to recommend the Vortech to those like me with GPS units without and external adaptor.