be an opened ended wave guide with directionality for simplicity only one receive antenna 312 can be used however in other embodiments multiple receive antennas 312 can be used in certain embodiments one power setting can be used for reading and an elevated power setting can be used for writing since passive rfid needs more power to write then to read having separate power setting for the read and write process can reduce exposure to high power rf fields for the tags for example in one embodiment the system can be configured to rely on tag encode information to determine what power setting to use this can be accomplished for example by writing information into each tag indicting the number of documents present in slot 302 for example when the first document is placed in slot 302 the number 1 can be written into the corresponding tag when a second document is placed into slot 302 then the number 2 can written into each tag the system can the be configured to read this number out of the tags in order to determine a power setting for example if the number 10 is read out of documents 304 then the system knows that 10 documents are present and it can be configured to automatically set the power to the appropriate level for 10 documents by doing this the system can eliminate the possibly of overpowering tags in situation where only 1 exist and under powering when 10 or more exists in another embodiment the transmission power of the interrogator including antenna can operate within a range for example the transmission power can start with the minimum power setting with a.