What is the difference between a dipole and a terminal pair antenna?

Answer 1

A dipole (Greek: di(s) = double and polos = pivot) is a pair of electric charges or magnetic poles of equal magnitude but opposite polarity (opposite electronic charges), separated by some, usually small, distance [1] [2] . Dipoles can be characterized by their dipole moment, a vector quantity with a magnitude equal to the product of the charge or magnetic strength of one of the poles and the distance separating the two poles. The direction of the dipole moment corresponds, for electric dipoles, to the direction from the negative to the positive charge. For magnetic dipoles, the dipole moment points from the magnetic south to the magnetic north pole — confusingly, the "north" and "south" convention for magnetic dipoles is the opposite of that used to describe the Earth's geographic and magnetic poles, so that the Earth's geomagnetic north pole is the south pole of its dipole moment. The only known mechanisms for the creation of magnetic dipoles are by current loops or quantum-mechanical spin since the existence of magnetic monopoles has never been experimentally demonstrated.

Since the direction of an electric field is defined as the direction of the force on a positive charge, electric field lines point away from a positive charge and toward a negative charge.

A communications device comprises a loop antenna having a plurality of feed terminals defining at least two terminal pairs. A controller is provided for selecting one terminal pair to enable reception or transmission from the loop antenna using the selected terminal pair. The selection of terminal pair is made based on the measurement of at least one parameter which is responsive to the proximity to the antenna of, for example, a user of the device. One terminal pair provides an antenna having matched impedance when the user is near the device, and the other terminal pair provides an antenna having matched impedance when the user is distant.

Answer 2

A dipole (Greek: di(s) = double and polos = pivot) is a pair of electric charges or magnetic poles of equal magnitude but opposite polarity (opposite electronic charges), separated by some, usually small, distance [1] [2] . Dipoles can be characterized by their dipole moment, a vector quantity with a magnitude equal to the product of the charge or magnetic strength of one of the poles and the distance separating the two poles. The direction of the dipole moment corresponds, for electric dipoles, to the direction from the negative to the positive charge. For magnetic dipoles, the dipole moment points from the magnetic south to the magnetic north pole — confusingly, the "north" and "south" convention for magnetic dipoles is the opposite of that used to describe the Earth's geographic and magnetic poles, so that the Earth's geomagnetic north pole is the south pole of its dipole moment. The only known mechanisms for the creation of magnetic dipoles are by current loops or quantum-mechanical spin since the existence of magnetic monopoles has never been experimentally demonstrated.

Since the direction of an electric field is defined as the direction of the force on a positive charge, electric field lines point away from a positive charge and toward a negative charge.

A communications device comprises a loop antenna having a plurality of feed terminals defining at least two terminal pairs. A controller is provided for selecting one terminal pair to enable reception or transmission from the loop antenna using the selected terminal pair. The selection of terminal pair is made based on the measurement of at least one parameter which is responsive to the proximity to the antenna of, for example, a user of the device. One terminal pair provides an antenna having matched impedance when the user is near the device, and the other terminal pair provides an antenna having matched impedance when the user is distant.

What she said.