US Patent 11289802 Millimeter wave impedance matching structures

An electronic device may be provided with a transceiver, a substrate, and antennas mounted to the substrate. The transceiver and antennas may convey signals between 10 GHz and 300 GHz. A radio-frequency connector may be mounted to the substrate. A coaxial cable may couple the transceiver to the connector. A stripline in the substrate may couple the connector to the antennas. Impedance matching structures may be embedded in the substrate for matching an impedance of the stripline to an impedance of the coaxial cable. The impedance matching structures may include a fence of conductive vias, landing pads, and a volume of the dielectric substrate defined by the fence of conductive vias and the landing pads. The impedance matching structures may be configured to perform impedance matching over a relatively wide bandwidth that includes the frequency band of operation for the antennas.