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Oscillators and Signal Sources
Published in J. C. G. Lesurf, Millimetre-wave Optics, Devices and Systems, 2017
Many millimetre-wave Gunn oscillators also employ a harmonic method of operation. The device is constructed so as to work efficiently at half (or sometimes a third) of the required frequency. The device then acts as its own non-linear frequency multiplier, converting some of the lower-frequency power into harmonic signals which can be extracted. Most GaAs Gunn oscillators used at frequencies above around 80 GHz operate in this way.
Design of dual-band planar thin absorber for vehicular radar test scenario
Published in International Journal of Electronics, 2023
Ying Zhang, Li-Yu Zhu, Xin-Mi Yang
A sample of the SSR design was fabricated using the screen-printing process, and the realistic view of the sample is shown in Figure 6. The conductive film of the sample is made of carbon ink. It is composed of 200 × 200 periodic units and occupies an area of 280 mm × 280 mm. Figure 7 shows the experimental setup for measuring the specular reflection of the sample. The measurement is carried out in a microwave chamber with a pair of broadband horn antennas serving as the transmitter and receiver. In this setup, the transmitter is connected to a frequency multiplier, which is in turn connected to a signal generator. The receiver is connected to a frequency down converter, which is in turn connected to a spectrum analyser. The distance between the horn antenna and the centre of the sample was set as approximately 2 m for the 24 GHz band test and 0.8 m for the 77 GHz band. To eliminate the influence of path loss and the reflection loss caused by connectors, wires, and horn antennas, the specular reflection of a metallic reference plate of the same size as the sample is also measured. The final specular reflection coefficient of the sample is obtained by normalising the reflection spectrum of the sample to that associated with the reference plate. Due to the limitation of the experimental setup, only a small range of elevation incident angles (5° to 20°) is considered in the experiment.
Impact of Inductor Placement on DC Bus Capacitor of Adjustable Speed Drives under Non-Ideal Supply Voltage Conditions
Published in Electric Power Components and Systems, 2023
Seshadri Gopalan, Krishna Vasudevan, Dinesh Kumar
As discussed in the previous section, the main objective of this paper is to study the difference in the impact of the supply voltage disturbances on the DC bus capacitor between the two variants of ASD. To evaluate the stress on the DC bus capacitor, it is required to compute all the frequency components present in the capacitor ripple current. It is to be noted that each frequency component in the capacitor current will heat the capacitor differently and to estimate the net heating effect, an index named Capacitor Heating Factor (CHF) is introduced in Ref. [17]. The CHF value is calculated using (2). The CHF value is also represented as 100/120 Hz component in capacitor datasheets, for example as given in Ref. [18]. In (2), Mfn is the multiplication factor or frequency multiplier that can be obtained from the datasheet of the capacitor. The switching frequency of the inverter (5 kHz) is used as an upper ceiling for the CHF calculation.
A fully integrated 2TX–4RX 60-GHz FMCW radar transceiver for short-range applications
Published in International Journal of Electronics, 2023
Dušan P. Krčum, Đorđe P. Glavonjić, Veljko R. Mihajlović, Lazar V. Saranovac, Vladimir M. Milovanović, Ivan M. Milosavljević
The core of the integrated FMCW radar sensor is fractional-N charge-pump-based PLL used for the generation of linear frequency modulated waveforms. In order to achieve desired loop dynamic which results in a good compromise between chirp linearity, bandwidth, and the overall phase noise, the input reference frequency of the PLL is chosen to be in the order of a few hundred megahertz. In this way, chirp linearity better than 0.01% is achieved over 7-GHz bandwidth. Apart from that, relatively high reference frequency helps to suppress certain noise contributors and improve the overall system phase noise. On the other hand, the drawback is the need for high frequency and high purity reference, which is hard to find and costly. Consequently, the reference frequency multiplier is designed and integrated into the proposed system.