| 摘要 |
<p>An electric field screen assembly comprises a primary screen 106 and two secondary screens (110a, 110b). Each screen has a tubular conductor defining a longitudinal gap throughout its length. The primary screen may accommodate a magnetic field generator such as a coil antenna 102 with ferrite rod 104. The gaps of the secondary screens are aligned with each other but are offset to the gap of the primary screen (e.g. by 180 degrees). In use, the electric field radiated from the gaps of the secondary screens are of equal strength and opposite phase to the electric field radiated from the gap of the primary screen, which minimises or cancels the production of interfering transverse electric fields. The secondary screens preferably have a combined length or surface area equal to the length or surface area of the primary screen. Multiple primary screens each associated with at least two secondary screens may be used.</p> |
