Half-wavelength antenna device and low-profile antenna device using same

The invention provides a half-wavelength antenna device which is small in size and capable of adjusting directivity. A half-wavelength antenna device for a vehicle is configured from a conductive plate (10), a half-wavelength element (20), and a passive element (30). The conductive plate (10) has a feed section (11) and a ground (12). The half-wavelength element (20) is vertically provided on the conductive plate (10), is connected to the power feeding unit (11), and is insulated from the ground (12). The passive element (30) is disposed parallel to and close to the half-wavelength element (20) so as to be electromagnetically coupled to the half-wavelength element (20), and the passive element (30) is insulated from the ground (12). 本发明提供一种小型且能够调整指向性的半波长天线装置。车辆用的半波长天线装置由导电板(10)、半波长元件(20)以及无源元件(30)构成。导电板(10)具有馈电部(11)和地(12)。半波长元件(20)竖立设置在导电板(10)上，与馈电部(11)连接并且与地(12)绝缘。无源元件(30)以同半波长元件(20)平行且接近的方式配置以与半波长元件(20)电磁耦合，并且该无源元件(30)与地(12)绝缘。