U3641/3641PHS/3641N is a portable spectrum analyzer that allows analysis with high stability by the adoption of a synthesized local oscillator. The U3641/3641PHS has the input impedance of 50Ω and the U3641N has 75Ω. To further increase portability there are three power supply choices: a battery pack, AC/DC adapter or an external DC supply. This allows a variety of power configurations. The 6 inch TFT color LCD display greatly improves the efficiency of waveform observation. By using the internal preamplifier, this analyzer’s strength comes into play for the analysis of the micro level signal.