xtex 43,
deep penetrating radar is fine.but you have to have a locator first that is not a metal detector. if you can find a positive area using your metal detector, there is a 100% chance that what you detected is only a decoy. instead, look for the area near the detected decoy. the real item is usually there. but you have to be patient and persistent. a good way to start is to look for the opposite area where your detected site was identified. you will know where the real treasure is if you can find a spot where there are so many positive detected areas in one spot. that is where the real item is. the real item is surrounded by so many decoys.
the reason for the ineffectiveness of the metal detector in jap treasure hunting is this. a real item is fully laden with anti-detectors. these are materials that are designed to repel any metal detection away from the real item. not only that, it will also lead you to the decoy items. that is the reason why there are so many failed diggings here in the philippines.
another reason why so many failed is there are also anti-scanners. anti-scanner materials may be in the form of a lead materials, corals, cement layers averaging from 10 feet or more, alternating hard cement layers with sand and corals, black sand, brown sand, clays, and so many gold dust near the real item. this is where your penetrating radar must be employed in the immediate environs. and a drill is a must also. you drill for actual results.
anti-scanners may not be able to repel your penetrating radar. but it will give you false depthness. if you can read that the item is located at 20 feet, chances are, the real item is located at 48 feet, or 90 feet. or 60 feet. or 100 plus feet. that would depend on the burial design of your area.
if the japanese engineers were not so skilled and cunning during the war days, almost all filipinos would have been rich by now as treasure hunting, i suppose, was a backyard activity during the late 1980's to 1990's. more and more filipinos are becoming discouraged nowadays. thus, you think like you are in the shoes of the japanese engineers. think like them. think about the anti-detectors and anti-scanners. that is the only treasure item in the world where there are anti-components like those i have mentioned.