An apparatus for use in wireless energy transfer to power a medical device, the apparatus comprising: a transmitting assembly configured to transmit electromagnetic energy, the transmitting assembly comprising: a transmitting resonant coil providing a first conductor and a first electrical insulating medium between coil turns of said first conductor; and an excitation coil inductively coupled to the transmitting resonant coil; a receiving assembly magnetic resonance coupled to the transmitting assembly, the receiving assembly comprising: a receiving resonant coil providing a second conductor and a second electrical insulating medium between coil turns of said second conductor; a power pick-up coil inductively coupled to the receiving resonant coil; wherein a first external capacitor is electrically connected to a start and end of said first conductor and a second external capacitor is electrically connected to a start and end of said second conductor; wherein said first and/or second insulating medium comprises one or more dielectric materials that is solid with a polygonal cross section, said first and/or second insulating medium providing a dielectric dissipation factor of 0.01 or less; wherein said first and/or second conductor has a thickness T of less than 0.0508 cm [0.020 inches] and said second conductor has a width W of 1.27 cm [0.5 inches] or less, wherein the thickness T is smaller than the width W, wherein the first and/or second conductor has an inter-turn spacing D greater than 0.00762 cm [0.003 inches]; and wherein said transmitting and/or receiving resonant coil (25. 35) has a diameter of 7.62 cm [3 inches] or less. a transmitting assembly configured to transmit electromagnetic energy, the transmitting assembly comprising: a transmitting resonant coil providing a first conductor and a first electrical insulating medium between coil turns of said first conductor; and an excitation coil inductively coupled to the transmitting resonant coil; a transmitting resonant coil providing a first conductor and a first electrical insulating medium between coil turns of said first conductor; and an excitation coil inductively coupled to the transmitting resonant coil; a receiving assembly magnetic resonance coupled to the transmitting assembly, the receiving assembly comprising: a receiving resonant coil providing a second conductor and a second electrical insulating medium between coil turns of said second conductor; a power pick-up coil inductively coupled to the receiving resonant coil; a receiving resonant coil providing a second conductor and a second electrical insulating medium between coil turns of said second conductor; a power pick-up coil inductively coupled to the receiving resonant coil; wherein a first external capacitor is electrically connected to a start and end of said first conductor and a second external capacitor is electrically connected to a start and end of said second conductor; wherein said first and/or second insulating medium comprises one or more dielectric materials that is solid with a polygonal cross section, said first and/or second insulating medium providing a dielectric dissipation factor of 0.01 or less; wherein said first and/or second conductor has a thickness T of less than 0.0508 cm [0.020 inches] and said second conductor has a width W of 1.27 cm [0.5 inches] or less, wherein the thickness T is smaller than the width W, wherein the first and/or second conductor has an inter-turn spacing D greater than 0.00762 cm [0.003 inches]; and wherein said transmitting and/or receiving resonant coil (25. 35) has a diameter of 7.62 cm [3 inches] or less.