SparkFun GPS Dead Reckoning NEO-M8U

hai there i want to use this module in my project but before using that i want to confirm few details does this product can recieve and send location without using antenna as i want to keep it undeground at a depth of 4 feet and i want to receive the location is it possible to receive the signals of lat and log.

or if i receive the signal of lat and log before placing it in the underground location and than remove the antenna can i get the signal as it can send the location without any signal(dead reckoning)

or please suggest any solution for my query

GPS signals do not penetrate the ground or the roofs of most buildings. GPS may not also work in forested areas.

Plan on a clear view of the sky when using GPS, and forget about dead reckoning, unless you use professional, aviation grade IMUs (USD $10,000 to $50,000 per unit).