Piezoelectric crystal resonator - with electrode positions and crystal shapes minimising second mode resonances by use of square crystal disc r mounted above base-plate

Crystals for oscillators in the higher frequency ranges produce inconvenient subsidiary resonances. To diminish these, a square crystal disc (11) with electrode strips (13, 14) fastened along one diagonal, has its X-Axis arranged to be at right angles thereto or, optimally, at an assessable angle. Six variations of the square or rectangular resonators are available to illustrate ways and means for further supporting the suppression of unwanted resonance modes, examples being square discs with rounded edges, chamfered edges, discs tapered from a central, flat area towards the edges, and discs spherically rounded on one side but flat on the other. The electrode strips are connected to holding elements (15, 16) which are fixed in an insulating base plate (17) and which are fitted into rod shaped fixing elements (18, 19).