The SMA (SubMiniature version A) connector is a widely - used semi - precision, ultra - small RF and microwave connector. With a threaded coupling design, it reduces signal reflections and attenuation at high frequencies. Its characteristic impedance is usually 50Ω, originally for 0Hz - 12GHz, now up to 26.5GHz. Small in size, it suits compact electronics. It has low insertion loss and good impedance matching, with an insulation resistance ≥5000MΩ. Applied in telecommunications, testing, aerospace, and industrial automation, SMA connectors ensure reliable high - frequency signal transmission.