Calibration circuit boards (112) may enhance the inter-band isolation of radiating units (114) of an antenna (100) that operates in more than one frequency band. The calibration circuit board (112) may be configured to transport signals to two or more radiating units (114). The radiating units (114) may be configured to operate in a first frequency band. The antenna (100) may include another radiating unit that is configured to operate in a second frequency band. The antenna (100) also includes one or more filters connected to one or more input ports (121) of the calibration circuit board (112).