I have recently purchased a single RTL-SDR kit that came with the dipole antenna. After much reading I have decided on building a 1/4 wave ground plane antenna and mounting it on the roof of my home. The main goal is to monitor the local 700MHz public safety/ems/fire. I am less that one mile from tower 1 and roughly 14 miles to tower 4. My question is what type of coaxial should I use? I'm a little confused about variations of impedance. Also planning on getting a second dongle so I will need a splitter but again i'm unsure of which one to get.