A dipole microstrip antenna fed through a J-Shaped balun is presented as the electromagnetic front-end of the RF radio for a wireless sensor solution in the 750 MHz frequency band. The designed antenna is meant for the communication between a wireless sensor placed within underground pipelines buried 3 meters, and surface monitoring bases. Additionally, a miniaturized version of the antenna is also proposed based on meanders technique, reducing in more than 47% the area of the antenna's substrate. Both antennas were tested in free-space and working alike scenarios where the measurements and simulation results shows good agreement validating the design and miniaturization process.