We are using Xbee pro s2c 802.15.4 PCB antennamodules in our project. When we analyze the rf signals in a signal analyzer, we see too many harmonics of the 802.15.4 signals, such as 4.8 ghz, 7.2ghz, 9.6 ghz, 12ghz etc. This is wierd situation that we do not want. In addition, if we jam the harmonic signals, for example at 4.8 ghz, the communication is lost between module. What should I do in order to suppress the harmonics? Can we use any bandpass filter between antenna and module if we decide to use RPSMA connector based Xbee module?