this page is intended to guide you through software defined radio. cubicsdr is a SDR application that has few requirements and is known to work well.
root # echo "net-wireless/soapysdr rtlsdr" >> /etc/portage/package.use root # emerge cubicsdr
gpasswd -a $USER usb #users need to be in the usb group to control the sdr dongle.
radio antenna length measured to the frequency and divided in half provides high gain, and strong signal reception. antenna lengths work in 1/2s 1/4ths 1/8ths and between, many cb antennas run something like 5/8ths length or 1/4 wave 109 inch whip antennas. there are many types of antennas, parabolic dish antennas provide long distance narrow signal beams good for point to point such as long distance wireless network connections.
here's a handy antenna length calculator, 1/2 wave is usually the best bet. http://www.csgnetwork.com/freqwavelengthcalc.html
145.800 is the international space station frequency. here is a link to track its real time position. https://spotthestation.nasa.gov/tracking_map.cfm
radio reference has handy frequency lists of local police for your police scanning fun https://www.radioreference.com/
rtl-sdr blog sells a kit for 30 dollars with a dipole antenna, with two antenna element length sets, and dongle on amazon. this is a good starting point to getting into listening to FM, AM, amateur radio, and CB. the kit is found here: