**5. Conclusion**

 The importance of aquifer water increased these days after decreasing the fresh water. A precise approach for the detection of buried nonmetallic objects is groundpenetrating radar (GPR). It should be importance of aquifer water increased these days after decreasing the freshwater. A precise approach for the detection of buried nonmetallic objects is ground penetrating radar (GPR). A novel, miniaturized, and low-cost antennas, which compromise between depth and resolution for different applications, are highly needed. This requires hundreds of conducting research activities in this area. However, although GPR has shown some promising results, the complexity of the problem requires certain challenges on the operation of GPR systems. One of the most serious hardware components for the performance of ground-penetrating radar (GPR) is the antenna system. First, a new compact Vivaldi antenna is designed to achieve ultra-wideband extending from 0.4 to 10 GHz and high average gain of about 17 dBi with average radiation efficiency of about 80%. The proposed antenna consists of dual exponential Vivaldi shapes on both dielectric substrates with the same feeding network. The GPR results in frequency range extending from 0.4 to 2 GHz of the water detection have also been investigated under certain system parameters. Second, ultra-wideband printed quasi-Yagi antenna has been introduced. The proposed antenna has the advantage of simple single feed structure which consists of a circulator balun with a microstrip line and a circulator slot. The antenna bandwidth extends from 47 to 150 MHz based on −6 dB reflection coefficient. The gains at the upper and lower bands are 3.5 and 6.5 dBi. It should be noted that the proposed antenna has the advantage of simple structure and stable end-fire radiation pattern, which makes it widely used in ground-penetrating radar. The average simulated gain in this band is about 5 dBi. At the same time, this antenna possesses low profile and miniaturization characteristics. Furthermore, the wide beamwidth and high gain can promise the antenna to be widely applied in many communication systems.
