Methods and systems for packet preamble sequences are provided. The slotted pin tool contains a plurality of pins having slotted ends designed to fit around each loci of material deposited on a surface, such as a microarray, without contacting any of the deposited material. The phase shifter controllably connects one or more of the switched lines in series between the input line and the output line, thus providing phase shifts of an input radio frequency signal between one of four discrete phase shift amounts.