Sure the metal disk/sheet/can helps a lot. I conducted an experiment last week to compare different sizes of ground plane. Found mag mount when placed over a metallic can/disk/sheet of 70mm dia or more, improves a lot. Please see details here:
Trial Run Results for Four Sizes of Ground Planes
This antenna is useless. I have conducted an experiment last week to find the best mag mount antenna. I found that the stock whip (which came with generic black dongle), when chopped to 52 mm length, gets optimum prformance.
Please see details here:
Trial Run Results for Three Types of Whip Antennas
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