we need rf id field detector and rfid power mapper The Power-Mapper is a battery free UHF RFID power meter The Vulcan RFID Power Mapper is a pocket size device that helps to map an RF field up to 15 meters in range for an RFID application. Only using RF power, this device is very sensitive and is capable of showing constructive and destructive interference patterns caused by multi-path. It works with all known European and US UHF RFID readers and can indicate to the user where a Gen2 tag may or may not be readable. With the Vulcan RFID Power Mapper you're no longer working in the dark. This meter is specially designed to show nulls in the UHF radio field at large distances from the antenna. You will find it hard to believe how large the signal variation can be, even quite close to the antenna. The meter will show polarization effects and destructive null cancellations, ground and water absorption. The meter relies on the power in the radio waves, so it cannot give a fails reading or have a flat battery. Almost 100% of the signal on at the antenna is shown on the meter, giving a massive 15+ meters (49+ feet) range. Show More