| 摘要 |
PURPOSE:To irradiate a search signal whose signal intensity is constant within a prescribed direction angle by exciting a wave front by a signal having an amplitude of a point of a prescribed curve corresponding to the eave front so as to form a transmission beam within the direction angle. CONSTITUTION: Electrodes divided into three by a main electrode 2, 2l in length and two sub electrodes 3, l in length is adhered closely to the upper side of a rectangular piezoelectric vibrator 1 and lne rectangular electrode 4 is adhered closely to the lower side. A signal where a prescribed carrier frequency is subject to amplitude modulation by a prescribed amplitude of pulse is fed to the primary winding of a transformer 5. One end of the secondarh winding 6 of the transformer 5 is connected to the electrode 2 and the other end is connected to the electrode 3, and the tap 7 is connected to the electrode 4. A signal curve fed to the electrodes 2-4 is expressed in SinA/A, where A=2piXtheta0, theta0 is a direction angle, ¦X¦<=l/lambda, and lambda is a wavelength of the carrier frequency. A signal with a reference amplitude (a) is fed to the electrode 4, a signal with an amplitude (b) is fed to the electrode 2 and a signal with amplitude (c) is fed to the electrode 3 respectively, the direction angle theta0=lambda/2l, and the signal intensity irradiated in the angle theta0 is constant as shown in figure (B). |
