Apparatus comprising: an antenna comprising a first end and a second end, the first end being connected to a first feed terminal and the second end being connected to a second ground terminal, the antenna further comprising a first conductive track having a loop structure disposed between the first end and the second end, the first conductive track being split into a first conductive part and a second conductive part at a first position of the first conductive track and the first and second conductive parts (34, 36) being joined together at a second position of the first conductive track, the first conductive part and the second conductive part each forming a U-shaped loop structure between the first and second positions (C,J) of the first conductive track, the first conductive part being configured electrically in parallel with the second conductive part, the first conductive part being configured to have a first electrical length that provides a differential resonant mode having a first operational frequency band; and a ground member having a first end and a second end and comprising the first feed terminal at the first end of the ground member, and the second ground terminal at the first end of the ground member, wherein the first conductive part comprises a portion (E-F) positioned at a distance relative to the first feed terminal and to the second ground terminal so as to electromagnetically couple to the first feed terminal and to the second ground terminal, wherein the second conductive part comprises a portion (H-I) positioned at a distance relative to the first feed terminal and to the second ground terminal so as to electromagnetically couple to the first feed terminal and to the second ground terminal, wherein the first conductive part is configured to provide the antenna, including the first conductive part, with an electrical length substantially equal to a wavelength of an electromagnetic wave in the first operational frequency band, wherein the portion (E-F) of the first conductive part is positioned approximately half way along the length of the conductive track including the first conductive part between the first feed terminal and the second ground terminal, wherein the portion (H-I) of the second conductive part is positioned approximately half way along the length of the conductive track including the second conductive part between the first feed terminal and the second ground terminal, and wherein a distance between the portion (H-I) of the second conductive part and the first and second ends (20, 22) of the antenna is between 0.1 and 5.0mm. an antenna comprising a first end and a second end, the first end being connected to a first feed terminal and the second end being connected to a second ground terminal, the antenna further comprising a first conductive track having a loop structure disposed between the first end and the second end, the first conductive track being split into a first conductive part and a second conductive part at a first position of the first conductive track and the first and second conductive parts (34, 36) being joined together at a second position of the first conductive track, the first conductive part and the second conductive part each forming a U-shaped loop structure between the first and second positions (C,J) of the first conductive track, the first conductive part being configured electrically in parallel with the second conductive part, the first conductive part being configured to have a first electrical length that provides a differential resonant mode having a first operational frequency band; and a ground member having a first end and a second end and comprising the first feed terminal at the first end of the ground member, and the second ground terminal at the first end of the ground member, wherein the first conductive part comprises a portion (E-F) positioned at a distance relative to the first feed terminal and to the second ground terminal so as to electromagnetically couple to the first feed terminal and to the second ground terminal, wherein the second conductive part comprises a portion (H-I) positioned at a distance relative to the first feed terminal and to the second ground terminal so as to electromagnetically couple to the first feed terminal and to the second ground terminal, wherein the first conductive part is configured to provide the antenna, including the first conductive part, with an electrical length substantially equal to a wavelength of an electromagnetic wave in the first operational frequency band, wherein the portion (E-F) of the first conductive part is positioned approximately half way along the length of the conductive track including the first conductive part between the first feed terminal and the second ground terminal, wherein the portion (H-I) of the second conductive part is positioned approximately half way along the length of the conductive track including the second conductive part between the first feed terminal and the second ground terminal, and wherein a distance between the portion (H-I) of the second conductive part and the first and second ends (20, 22) of the antenna is between 0.1 and 5.0mm.