At low frequencies the free space wavelength becomes very large. For example, the BBC Radio 4 LW transmissions use a carrier frequency of 198 kHz. This corresponds to a free space wavelength of 1514 metres. It isn't practical to make halfwave dipoles at these frequencies, but Hertzian dipoles are a possibility. Figure 7.6 shows some examples of the use of Hertzian dipoles at long wavelengths.
Most car radios use a 'whip' antenna.
This visible rod of metal forms one half of the antenna dipole. The other half is the rod's image reflected in the metal body of the car. At first glance it may appear that it is the cables which are the antenna and that the masts are purely to hold the antenna well above the ground. As with the car whip, the masts form one half of a Hertzian dipole. The other half being their reflection in the ground.