HackRF One is a wideband software radio transceiver with a USB interface.

hardware notes:

Schematic and layout files were designed in KiCad, an open source electronic
design automation package.

order of copper layers:
    Copper 1:  C1F (front)
    Copper 2:  C2
    Copper 3:  C3
    Copper 4:  C4B (back)

PCB description: 4 layer PCB 1.6 mm
    Copper    1   0.035 mm
    Prepreg 1-2   0.2104 mm
    Copper    2   0.0152 mm
    Core    2-3   1.065 mm
    Copper    3   0.0152 mm
    Prepreg 3-4   0.2104 mm
    Copper    4   0.035 mm

7628 prepreg with Er=4.6 (+/- 0.1)
required impedance: 50 ohm (+/- 5%) 11.55 mil microstrip impedance
double side solder mask green
single side silkscreen white
5 mil min trace width and
5 mil min isolation