are described below, but a great variety of designs and types exist. Many have a dial on the antenna with a number of different settings to alter the antenna's reception pattern. This should be rotated with the set on while looking at the screen until the best picture is obtained. Rabbit ears The oldest and most widely used indoor antenna is the rabbit ears or bunny ears, which are often provided with new television sets. It is a simple half-wave dipole antenna used to receive the VHF television bands, consisting in the US of 54 to 88 MHz (band I) and 174 to 216 MHz (band III), with wavelengths of . It is constructed of two telescoping rods attached to a base, which extend out to about length (approximately one quarter wavelength at 54 MHz), and can be collapsed when not in use. For best reception, the rods should be adjusted to be a little less than wavelength at the frequency of the television channel being received. However the dipole has a wide bandwidth, so often adequate reception is achieved without adjusting the length. The measured gain of rabbit ears is low, about ―2 dBi, or ―4 dB with respect to a half wave dipole. This means it is not as directional and sensitive to distant stations as a large rooftop antenna, but its wide angle reception pattern may allow it to receive several stations located in different directions without requiring readjustment when the channel is changed. Dipole antennas are bi-directional, that is, they have two main lobes in opposite directions, 180° apart. Instead of being fixed in position like other antennas, the elements are mounted on ball-and-socket joints and can be adjusted to various angles in a "V" shape, allowing them to be moved out of the way in crowded quarters. Another reason for the V shape is that when receiving channels at the top of the band with the rods fully extended, the antenna elements will typically resonate at their 3rd harmonic. In this mode, the direction of maximum gain (the main lobe) is no longer perpendicular to the rods, but the radiation pattern will have lobes at an angle to the rods, making it advantageous to be able to adjust them to various angles. Whip antenna Some portable televisions use a whip antenna. This consists of a single telescoping rod about long attached to the television, which