Abstract: A frequency synthesizer for adding large frequency steps to an initial frequency. A first phase lock loop divides the input frequency Fo+.DELTA.(.DELTA. being the sum of smaller frequency steps) by a rational division factor and adds to the result a standard frequency P in a fixed integral ratio with the large frequency steps to form an intermediate frequency Fi. A second phase lock loop (O.sub.S -E-G-D.sub.3 -CPF.sub.2 -FL.sub.3) multiplies the intermediate frequency by a rational factor, equal to (N+1)/D. This second loop first divides (in D.sub.3) the intermediate frequency by an integral fixed ratio D and then compares (in CPF.sub.2) the result Fi/D to a beat between the output frequency Fs and a harmonic N-Fi of the intermediate frequency.

Abstract: A Frequency synthesis stage comprises two phase locked loops. The first (O.sub.1, D.sub.1, M, CP.sub.1, D.sub.2) divides the frequency Fo+.DELTA. derived from preceding stages by N/Q, N being a variable integer, and adds to the result a standard frequency P which is in a fixed ratio with a value representative of large frequency steps so as to give an intermediate frequency F.sub.A, while the second (O.sub.2, M.sub.0, M.sub.1, CP.sub.2 D.sub.3) multiplies F.sub.A by NQ/r. P and Q are selected so that the product PQ is approximately equal to the mean of the limit values desired for the output frequency.

Abstract: A decimal frequency synthesizer in which, for each decade, two identical sets of four arithmetic progression frequencies are generated by programmed frequency divisions effected in parallel from a standard frequency and applied to two mixers. The first mixer further receives the frequency from the preceding decade and is followed by a divide-by-2 divider, whereas the second mixer is further receives the output of said divider and is followed by a divide-by-5 divider.

Abstract: A microwave coaxial switch has a central conductor which comprises two fixed segments connected by a movable segment, controlled by a switch member. The resilient ends of the fixed segments come into engagement with the contacts of a quadripole such as an attenuator cell, when they are freed from the movable segment, this latter having come into engagement with the ground conductor.

Abstract: A synthesizer comprises a basic synthesizer (1) generating a frequency Fo+.xi., wherein .xi. can be varied by small incremental steps, and a phase-locking loop (including a divider 2, a comparator 3, a filter 6, a mixer 4) setting the frequency of an intermediate oscillator (5) to a value Fi=(Fo+.xi.)/(NR+M), wherein NR+M is the division rate of divider 2. A fractional multiplier including an output oscillator 8, a mixer 9, harmonic generators 7 to 12, a divider 13 and a phase comparator 11 multiplies intermediate oscillator frequency Fi by N+(M/R), wherein R preferably is 5. The synthesizer can be used to synthesize frequencies up to several gigahertz.

Abstract: A microwave spectrum analyzer comprising a first mixer which provides beats between the output of an YIG oscillator and the spectrum to be analyzed. A second mixer carries out a fixed transposition of said beats. The said YIG oscillator is locked to harmonics of the frequency of an auxiliary oscillator controlled by a phase-frequency comparator. The latter is adapted to receive on the one hand the frequency, divided by N of a synthesizer, and on the other hand, the beats between the frequency of said auxiliary oscillator and that of a crystal oscillator.

Abstract: Synthesizer including a VCO-type oscillator covering the range from 300 to 610 MHz and driving a first mixer; a source of 80 MHz standard frequency, followed by a frequency multiplier and a tunable filter driving the first mixer; a second, sampling-type mixer driven on the one hand by the output of the first mixer and on the other hand by the standard frequency divided in a divider by 8. The output from the second mixer controls the frequency of the oscillator.Application to the production of a synthesizer with very high spectral purity.

Abstract: A frequency synthesizer with multiple phase control loops offers the facility of a wide range of frequency adjustment without any discontinuity effects either in frequency or amplitude, and includes at least three phase-controlled oscillators, the first effecting the generation of the smaller steps, the second that of the large steps and the third adding algebraically the frequencies of the two first. On a positive increment of the output frequency, the frequency of the first oscillator (0.sub.1) increases and then decreases, and so on, in two successive perfectly linked modes of operation. The synthesizer may be applied to the construction of a programmable wobbulator.

Abstract: Frequency-modulated electrical signal generator comprising two oscillators, the first delivering a modulated output frequency and driving a mixer which receives in addition the output of the second oscillator. The latter is phase-controlled by a loop comprising the mixer, a filter and a first phase comparator which receives an intermediate frequency. The first oscillator is controlled by a loop including the second oscillator followed by an adjustable frequency divider and a second comparator receiving a reference frequency.

Abstract: A frequency synthesizer operating in the quaternary system of numeration and comprising a plurality of "quaternade" units, each including a frequency inserting element with a mixer which receives respective frequencies equal to 63 A, 64 A, 65 A and 66 A, A being a predetermined frequency. The said frequencies are generated from a common standard frequency through dividing the standard frequency by variable ratios generating harmonics of the resulting frequencies and filtering.