Obstacles like buildings and houses have minimal impact on broadcast reception due to their size relative to the wavelength of radio transmissions. The wavelength of typical radio signals is much larger than the dimensions of most structures, allowing signals to diffract around them. This phenomenon is similar to how visible light interacts with objects, where larger obstacles can cause more interference. Additionally, radio waves can penetrate some materials, further reducing potential disruptions. Overall, the physical properties of radio waves enable effective transmission despite nearby obstacles.