Helmholtz-Coils are especially designed to generate precisely defined magnetic fields from DC to the upper end of the audio frequency range and beyond. The generated fields are in a strongly linear relation to the coil current. The field- strength can be 详细
Biconical Antennas have dipole like characteristics (e.g. circular directional pattern in the H-plane,"8"-shaped in the E-plane, fixed phase center, comparable gain), with an enormous wide bandwidth achieved by the double cone elements. 详细