Hi everybody. I am viewing EEVBlog for a longer time and learned a big from here, but now i have some problem. I am working on a TRX based on RFM12BP, but on the output i am getting a lot garbage on the whole range from 100MHz to 1Gig. I am using 869.400MHz (869.4MHz, while it is a long range device and i need to go to the limit of output power (500mW). The question is coult someone help me to design a bandpass filter for the antenna? In and out impedance is 50Ohms. The spectral graph that was measured is attached.