A broadband planar power divider/synthesizer comprises a microstrip power divider/synthesizer network, a broadband gradient line impedance converter and multiple planar stripline isolators, the microstrip power divider/synthesizer network comprises multiple branch transmission ports and a single synthesized transmission port, each branch transmission port is connected to a planar stripline isolator, the synthesized transmission port is connected to the broadband gradient line impedance converter first end, the broadband gradient line impedance converter width decreases gradually from the first end to the second end
