RF Explorer is a handheld digital spectrum analyzer, a really economical tool for work in all popular frequency bands. It is based on an extremely integrated frequency synthesizer and double well balanced mixer which uses high performance, compact size, low usage and low cost. It has actually been designed to be used similarly well outdoor and indoor, and can be linked to a PC for extra functionality utilizing basic mini-USB 2.0 connector. This design consists of a WSUB1G baseline unit plus an RFEMWSUB3G Expansion Module conveniently put together and tested. It features two SMA ports and two antennas, a good Nagoya NA-773 wideband telescopic antenna for all Sub-GHz frequencies and a whip helical for 2.4 GHz band. Extra, specific band antennas may be needed to cover efficiently some of the frequencies supported.