DISPOSITIF DE CAPTATION ET DE RAYONNEMENT DES ONDES ELECTROMAGNETIQUES

• Main Author: A. A. BOZHKO, V. V. LAVRINENKO, M. M. NEKRASOV ET I. A. KARTASHEV
• Format: Patent
• Language: French
• Published: 19.11.1976
• Subjects: ANTENNAS, i.e. RADIO AERIALS; BASIC ELECTRIC ELEMENTS; ELECTRICITY

1499033 Aerials KIEV POLITEKHNICHE INST IM 50-LETIA VELIKOI OKTYABR SOTSIALISTICHE REVOL JUT 4 March 1975 8977/75 Heading H4A An aerial comprises a piezoelectric element 1, the element having first 4 and second 5 sections acoustically coupled together the first section 4 being connected to a transmission line 8 and the second section 5 radiating or receiving e.m. waves into or from free space. Different elements can be constructed to cover the frequency range 102-107 Hz. As shown in Fig. 1 the section 4 is connected to the transmission line 8 by leads from electrodes 6 and terminals 7 in the insulating housing 2. The second section 5 may also carry an electrode 9 which may be connected to a layer of foil 15 spread on the housing surface. As shown in Fig. 2, the element 1 may be composed of two acoustically coupled layers 10. The mode of vibration of the element is governed by the selection of polarization directions (indicated as arrows) relative to the electrodes 6. The aerial efficiency is increased by the introduction of a symmetrically disposed third section 51, by using a ring form for electrodes 6 (not shown), by composing at least the sections 5, 5' from acoustically coupled half-wave units (Figs. 4, 6, not shown) and by using materials of differing electrical and acoustical impedances for sections 4 and 5. The operating frequency can be lowered by loading (12, Fig. 3, not shown) with a body of relative permitivity less than 100 and by attaching the element 1 to a support (11). In the last case, mechanically compensating elements (16, Fig. 8, not shown) may be disposed on the support. In another embodiment (Fig. 9, not shown) the selectivity and bandwidth are increased by using two piezoelements with different operating frequencies. The use of more than one element imparts directivity to the aerial. The elements 1 may be clamped at nodes (not shown) or held in place by rubber packing 3. The elements may be discs (Fig. 5, not shown) or cylinders (Fig. 4, not shown).