Since now it’s available in stock a new accessory in our store: low cost multiband (L1/L2/L5/L6) GPS antenna RF splitter. Use it to compare 2 different receivers with the exact same antenna location, or to compare the same receiver with different settings under the same conditions!
The splitter is powering the antenna via the GPS receiver #1 while blocking the power to the antenna from GPS receiver #2 so you don’t need to worry about powering the antenna externally.