Some Numerical and Experimental Observations on the Growth of Oscillations in an X-Band Gunn Oscillator

Abstract

Abstract-The dynamics of the onset of oscillations in a wave guide cavity based Gunn Oscillator (GO) has been critically examined through numerical simulations and experimental studies.The transition of the GO from a non-oscillatory to an oscillatory state and the same in the reverse direction occurs at different critical values of the dc bias voltage applied to the GO. In presence of a weak RF field in GO cavity, oscillations with broad band continuous spectrum and multiple discrete line spectrum are observed at the GO output for different values of dc bias below the above mentioned critical values. Analysing the numerically obtained time series data, chaos quantifiers have been obtained to prove the occurrence of the chaotic oscillations in the GO. Experimental results and observations of numerical simulation show good qualitative agreement.

Effects of Chaotic Perturbation on a Periodic Gunn Oscillator

“…Among these parameters, c is most sensitive to bias voltage variation. So the tuning of value of c is taken in simulation study [17]. Values of Ω and q s are taken equal to 1.27 and 0.15 for a set of simulation.…”

“…Forcing it by an external signal of amplitude and normalized frequency, q s and Ω, respectively, one gets chaotic oscillations. Thus the equation of GO capable of producing chaotic oscillations is [17],…”

“…As such, nonlinear dynamics of forced GOs has drawn attention of the researchers [14][15][16]. Experimental studies presented in [17] have shown that building up and quenching phenomena of oscillation in a GO due to the variation of operating dc bias voltage show hysteresis. Also an under-biased GO (i.e., a GO biased below the threshold dc bias voltage required for normal oscillation) breaks into chaotic oscillation under the influence of an external periodic signal of appropriate frequency.…”

Studies on the Dynamics of a System of Bilaterally Coupled Chaotic Gunn Oscillators

“…The coefficients a, b, c, d are related with the device and the cavity parameters and implicitly depend on the magnitude of the applied dc bias (V B ) across the Gunn diode [20].…”

“…As a logical extension of the studies on the BCPGO [14], one may question on the modification of the dynamics of the system if the GOs become chaotic. Adopting the simple method reported in [20] a BCPGO can be converted into a BCCGO system. Here, the GOs would be operated in the under bias condition and a weak external RF field would be injected in the cavities.…”