An antenna transmits and receives radio waves with a particular polarization which can be reoriented by tilting the axis of the antenna in many (but not all) cases. The physical size of an antenna is often a practical issue, particularly at lower frequencies (longer wavelengths). Highly directional antennas need to be significantly larger than the wavelength. Resonant antennas usually use a linear conductor (or element), or pair of such elements, each of which is about a quarter of the wavelength in length (an odd multiple of quarter wavelengths will also be resonant). Antennas that are required to be small compared to the wavelength sacrifice efficiency and cannot be very directional. Fortunately at higher frequencies (UHF, microwaves) trading off performance to obtain a smaller physical size is usually not required. COUNT 5
QSN1 What is the essential difference in radio waves transmitted by an antenna? ANS1 polarization QSN2 How can this be adjusted more easily than changing antenna types? ANS2 tilting the axis QSN3 When might the size of an antenna cause an issue? ANS3 at lower frequencies QSN4 What size antenna would not be good when the antenna needs to be directional? ANS4 small QSN5 There is a relationship between the size of the antenna and the size of the wavelength with what antenna type? ANS5 Highly directional