Printed dual-band Yagi-Uda antenna and circular polarization antenna

A printed dual-band Yagi-Uda antenna, comprising:

• a substrate;
• a first driver, formed on the substrate, for generating a radiation pattern of a first frequency band;
• a first director, formed at a side of the first driver on the substrate in a first direction, for directing the radiation pattern of the first frequency band toward the first direction;
• a second driver, formed between the first driver and the first director on the substrate, for generating a radiation pattern of a second frequency band, wherein a distance between the second driver and the first director makes the first director an open-circuit element of the second frequency band;
• a reflector, formed at another side of the first driver on the substrate in an opposite direction of the first direction, for reflecting both the radiation patterns of the first frequency band and the second frequency band toward the first direction;
• a transmission line, formed along the first direction on the substrate, sequentially coupled to the reflector, the first driver and the second driver;
• a matching element, formed adjacent to the second driver on the substrate, for increasing a bandwidth of the second frequency band as a reactive load;
• wherein, the substrate includes a first metal layer and a second metal layer, the matching element is formed in the first metal layer, and the reflector is formed in the second metal layer.