We recently camped with a Casita friend who had a Wilson Sleek. She had a Wilson ground plane magnetic antenna on a circle of metal about 5 inches diameter, mounted on a pvc pipe mast. The antenna base was about as high as the trailer roof. At my campsite, my phone had 1X, 1 bar. Thirty feet away in her Sleek, I had 3G, 4 bars. I bought a Sleek when I returned home.
2011 Escape 5.0
2011 Ford F150 5.0