| 摘要 |
The invention sets forth an aerial (1) having at least one plane spiral arm (3a . . . 3d) being provided in front of and parallel with a plane face of a reflecting member (4), the aerial furthermore having a ferro-electric member (2) arranged between the at least one spiral arm (3a . . . 3d) and the reflecting member (4). An interface circuit provides an adjustable bias voltage over the at least one arm (3a . . . 3d) and the reflecting member (4) for varying the dielectric constant of, and thereby the delay through, the ferro-electric member (2). In this manner, the aerial is tuned to various frequencies of interest and providing for an enhanced antenna gain. According to a further aspect of the invention an interface circuit provides individually controllable bias voltages to respective spiral arms for accomplishing tuning of the axial ratio and/or impedance match of the aerial. |
