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A dipole antenna 34 comprises a loop 36 as a first pole and an appendage 42 comprising a strip 44 terminating in a pad 46 as a second pole. The circumference of the loop is in the order of one half-wavelength of an operating frequency and an effective length of the appendage is at least 0.15 times t

A dipole antenna 34 comprises a loop 36 as a first pole and an appendage 42 comprising a strip 44 terminating in a pad 46 as a second pole. The circumference of the loop is in the order of one half-wavelength of an operating frequency and an effective length of the appendage is at least 0.15 times the wavelength. The dipole antenna 34 is shorter than conventional half-wavelength dipole antennas, has a better frequency response and the antenna impedance ZA is dependent on the position of a feedpoint 38 in the loop 36. The antenna may be used with transponders for electronic radio frequency identification systems.

대표청구항 ▼

1. A dipole antenna comprising:a first pole comprising an electrically conductive loop having no more than one interruption and providing a high impedance feed mechanism for the antenna at a feedpoint on the loop; and a second pole comprising an electrically conductive appendage galvanically connect

1. A dipole antenna comprising:a first pole comprising an electrically conductive loop having no more than one interruption and providing a high impedance feed mechanism for the antenna at a feedpoint on the loop; and a second pole comprising an electrically conductive appendage galvanically connected to the loop in a connection region on the loop and extending outwardly from the loop, the loop and the appendage forming part of a layer on a substrate; the feedpoint being circumferentially spaced on the loop from the connection region; thereby to provide an off-center fed dipole antenna with the feed point at a higher impedance than the connection region.