The present article proposes a novel method to reduce phase noise in a PLL based X-Band source consisting of oscillating and non-oscillating components for the use in Pulse Doppler radar. It also provides phase noise performance stabilization under random vibration. The method consists of improved electrical design and PCB layout, noise filtering technique and passive isolation scheme to suppress vibration-induced noise. Acceleration sensitivity is an important requirement for radars and sensors mounted in unmanned aerial vehicles, aircrafts, missiles and other dynamic platforms. These systems provide superior performance when subjected to severe environmental condition. However, mechanical vibration and acceleration can introduce physical deformation that thereby degrades the frequency source generated signal phase noise. It effects the complete radar system that depends on frequency source performance. The development and testing of a stable X-Band source at 10.64 GHz using indirect method has been carried out which proved that the phase noise is stable both in steady state and under random vibration of 7g magnitude. The study of critical design aspects of test fixture, test object mounting arrangement, investigation on vibration response and performance stabilization along with description of test setup and measurement procedure has been reported. An improvement of around 35-40 dB in phase noise is achieved at close-in offset frequencies. Few challenges and suggestions for the accurate measurement of random vibration testing for frequency sources have also been mentioned.

In this article, a qualitative work is carried out based on research of uniform PRF signal for phase noise analysis and accuracy parameter for RF sensor design. Presence of large clutter level in target return needs in-depth analysis of phase noise impact in clutter cancellation and importance of PRF selection in RF sensor processed SNR or accuracy. Detailed investigation of phase noise parameter in pulsed RF secnsor is examined out for target identification and tracking purpose. Critical aspects of phase noise in multiple PRF mode has been analyzed and Matlab simulations are carried out to support theoretical aspects of noise effects at particular offset. Impact of phase noise in clutter cancellation for uniform PRF waveform and multiple uniform PRF waveforms is evaluated in terms of SNR, sensor accuracy and allied limitations. Thus, outcomes can be utilized to unique analysis of PRF selection and phase noise together for RF sensor accuracy. Present work findings and results have been validated using simulation environment. This research outcomes offer great importance in design of highly accurate RF sensor.

The present article presents critical aspects of RF system development process and its sequential phases along with associated challenges. It also discusses importance of active and passive components thermal behavior and their impact in overall system performance. The study on performance deviation of these components with temperature change has been reported. Potential issues for gain variation and frequency selectivity have been analysed and suitable solutions are explored accordingly. Implementation of temperature stabilization method in designed RF product has been carried out during prototype development. Practical achieved results are noted down during testing and measurement to monitor effectiveness of thermal stabilization mentioned in it. Finally, wideband flat gain response has been achieved by implementation of thermal stabilization for active and passive components to avoid any performance degradation.

A component attachment process and noise sustain mechanism have been proposed in this article to realize a quad channel high gain phase-matched receiver. A critical issue in the conventional soldering process is the formation of unwanted voids beneath the component which affects gain and phase performances of the system under consideration at microwave frequencies. Assembly conditions and process sequence followed by bonding process for oscillation-free flat gain, low noise figure (NF), and sustain phase noise performance are selected to ensure less than 2% void formation. Vapor phase assembly (VPA) at 250 degrees is performed in case of longer RF track PCBs for avoidance of any phase mismatch. Experimentations on assembly conditions, number of bonding stands, and bond wire thickness are carried out for multiple trails respectively. In each step, X-ray scan reports and monitored performance results have been analyzed to set checkpoints in the complete development process. Finally, gain, NF, and phase noise responses of developed multichannel receivers have been analyzed. Multichannel pulse repetition time (PRT) controlled microwave module has been realized and tested over thermal screening for several cycles and performed random vibration (RV) test to validate the proposed component attachment process. Electrical parameter results achieved using proposed techniques have been compared with conventional method results in this article. The proposed component attachment process is equally applicable to the realization of any other RF circuit design to be operated under ambient conditions and harsh environments.

Some critical investigations on the phase non-linearity in Delay Line Discriminator (DLD) are reported in this article to increase phase noise measurement sensitivity. A critical issue of phase non-linearity in wide-band phase noise measurement is studied during practical system realization. Substrate attachment process for longer delay line printed circuit board (PCB) over metallic housing has been proposed for DLD based phase noise measurement system development in details. Conventional lead or lead free reflow methods for PBC attachment over metal base have void formation issue for large surface area. Phase nonlinearity effect has been analyzed for its importance in measurement sensitivity. Vapour Phase Assembly (VPA) at 250 °C is suggested in case of long track PCBs for avoidance of any phase mismatch. Finally, non-linearity result of conventional reflow are compared with VPA substrate attachment. Examination of non-linearity reduction within ± 20° for improving measurement sensitivity is applicable for narrow and wideband phase noise analyzers.

In this article, a low phase noise signal source to be used as local oscillator in pulse Doppler radio frequency (PDRF) sensor is proposed. Innovative design techniques for realization of the low phase noise frequency source using phase-locked loop (PLL) and dielectric resonator (DR) are presented. Qualitative investigations have been carried out on the effect of phase noise in PDRF sensor performance. An X-band vibration resistant PLL-based frequency source with phase noise better than -95 dBc at 1 kHz frequency offset has been designed here. It also presents the design of a 7.6 GHz low phase noise, vibration resistant DR oscillator. Systematic analysis of the key design aspects, their thermal-vibrational stability, and ease of integration with hybrid microwave integrated circuits have been disclosed. A prototype board is fabricated, assembled in a compact mechanical enclosure of dimension 55 x 55 x 15 mm3. Finally, developed module is experimentally validated under 7.6 g rms magnitude random vibration test in three axes and compared results with other state of-the-art similar works. The comparison clearly shows the merit of present research work over other similar existing works.

This paper present unique design technique of 4 channel downconverter receiver for monopulse AESA based target tracking radar. Sum and difference channels are designed along with Guard channel which possess extra gain requirement and stringent noise figure as per system requirements. Supportive calibration mechanism via innovative switch circuitry is incorporated along with Guard channel thus avoids need of dedicated additional channel. In line with system needs design methodology is chosen, block diagram is developed, circuit and EM simulations are carried out in ADS, CST and Cascade software and critical aspects of designing such receiver are also disclosed.

The purpose of this paper is to disclose improved crystal based frequency source system covering design techniques and experimental methodologies for the stabilization of phase noise performance of X-band phase-locked loop (PLL) at 10.6 GHz. Phase noise performance of PLL-based unit under test (UUT) is prone to disturbance occurred in random vibration profile frequency spectrum. UUT self-resonance plays vital role in occurrence of disturbance in random vibration profile. The stabilization of phase noise performance during dynamic (random) vibration condition is achieved by following methodologies, i.e. vibration-isolator compensation techniques, purification tactic for reference crystal of PLL, and spatial location analysis for finding out mounting position of reference crystal. Spatial analysis helps to filter out UUT self-resonance frequency from random vibration spectrum which leads to reduction of frequency resonance pickups during random vibration testing.

The purpose of this article is to understand significance of random vibration stress screening for high frequency source module. Analysis of random vibration test with their impact on complex frequency source module performance is explained. Importance of sensitive component, structural analysis and design compensation for frequency source module are explained for random vibration test. Analysis of practically observed performance degradation results of frequency source during vibration testing is done. Performance stabilization of frequency source achieved through prior analysis, usage of filtering mechanisms and removal of measurement errors using well-defined procedure is disclosed. Solutions leads to development of frequency module performance as per design during testing.

The purpose of this article is to study of thermal stress screening process for RF system. Concept of thermal cycling and thermal chamber for simulating thermal conditions as per design requirement is discussed. Importance of thermal cycling test for RF system, its procedure, and parameter has been explained. Study on different error sources occurs during thermal cycling and associated risk assessment for RF system under test is done. Finally, precautions during thermal cycling test for smooth conduction of test are mentioned.

Some critical investigations on direct substrate-attachment process over double-sided metallic housing have been discussed in this article under wideband instantaneous frequency measurement receiver development in detail. Conventional reflow method-based substrate-attachment techniques have many issues when the surface area becomes larger. One of the major issues is that it forms unwanted voids beneath the substrate, which affects phase performances at higher frequencies. To overcome these issues, a direct substrate-attachment process has been carried out under inert environment using a customized vaporphase assembly (VPA) process. The final temperature and its profile have been readjusted by tuning gradient and duration of rise, equilibrium, and fall times to customize the VPA process. Conventional methods are compared with VPA of direct substrate attachment for large (phi approximate to 265 mm) surface area. Experimentations of direct substrate attachments are carried out for diverse quality of nickel (Ni)- and silver (Ag)-plated housings, respectively. In each step of plating depth, the percentage of impurities in plating and X-ray scan reports have been analyzed to make crucial decisions about attachment improvement, and limits have been set for mass production. Modules have been made and tested over extensive thermal cycling from -40 degrees C to +71 degrees C and random vibrations in three axes to establish the analysis.

This article explains design methodologies, appropriate solutions of development challenges, testing and validation of high performance microwave frequency up-converter module operating in X-band. Multi-function up-converter prototype has been designed and developed for sophisticated applications. This article describes detailed conceptual level planning at various stages and sequential phases of product development. Design risks allied with electrical and mechanical plans are explained based on an area of application for a developed prototype. Product specification formulation, block diagram development, schematic design and simulation of critical components have been accomplished. The importance of assembly method, quality inspection along with testing measures are also explained in this article. Functional testing and measurement of a developed prototype with importance of different parameters have been covered. Finally, a prototype is tested under different stress screenings for checking performance redundancy in operational environmental conditions as per application.

The purpose of this paper is to give temperature compensation techniques for active components and better design methods for passive circuits for robust trans-receiver modules used in airborne radar application. Performance of any trans-receiver module is dependent on active or passive components used in it. Gain stabilization techniques for mitigating any performance deviation are discussed. Parameter variation like gain, selectivity with temperature changes are shown later, compensation technique and method are discussed for elimination of such issues with active or passive blocks of any trans-receiver system. Finally, practical implementation of suggested compensation techniques and methods for performance stabilization are shown which are necessary for making high robust trans-receivers for electronic system used in airborne application.

This paper presents the design and analysis of multi-section dual band branch line coupler (BLC) using meta line structures. This BLC incorporates enhanced bandwidth of multi-section topology and miniaturization capabilities of composite right/left hand (CRLH) configuration structures. A prototype is designed and fabricated to operate at GSM 900 MHz and ISM 2.45 GHz. The designed structure achieves miniaturization of 47% with coupling bandwidth 18% in lower band and 28.1% in upper band. Phase imbalance between the output ports in both the bands is ≤ 5 0 for this coupling bandwidth.

Phase noise performance of microwave synthesizers is sensitive to vibrations to some extent. The reference source is one of the prime performance-limiting components in microwave systems ranging from simple RF receivers to advanced radars. Phase noise performance improvement of PLL during random vibration environment is discussed in this article. It's basically achieved by following methodologies, viz; vibro-isolator compensation technique, purification tactic of source crystal reference for PLL and also analyzed the spatial location for mounting of crystal reference and avoid UUT (unit under test) resonance out of frequency spectrum (PSD) of Random vibration profile. We point out some challenges and provide suggestions for the accurate measurement of vibration sensitivity of Airborne Radar system.

The purpose of this article is to understand importance of environmental stress screening with special emphasis on random vibration test, risk assessment linked with system which is subjected to such test. Well-explained techniques of filtering sources of error are explained with special focus on vibration fixture design. Finally explained concept of structural research and procedure to carry out test while covering precaution for failure avoidance of any electronic system. It allows a system to operate to its full capability when exposed to such harsh environment of random vibration.

This paper proposes a design of broadband microwave gain equalizer with asymmetric parabolic gain-slope profile to compensate the gain variations of the amplifier over frequency. Since the gain blocks (i.e. amplifiers or tubes) typically follows asymmetric parabolic nature over the frequency, an equalization circuit with desired attenuation control is necessary to compensate while maintaining the parabolic nature of equalization. The simulated results show that the proposed design of gain slope equalization has an asymmetric performance from 1.5 GHz to 10 GHz with good impedance matching and profile selectivity. Equalization curve is very much suitable to meet the practical requirements of amplifiers flat gain response of wide band receivers for modern electronic warfare.

Phase noise performance of PLL during Random vibration environment is discussed in this article. Experimentation is carried out in X band frequency. It's basically achieved by following methodologies, via; vibration- isolator compensation technique, purification tactic of source Crystal Reference for PLL and also analyzed the spatial location to find out center of gravity for mounting of Crystal Reference. It helps to avoid UUT (unit under test) resonance out of frequency spectrum (PSD) of Random vibration profile which avoids resonance pickups during testing in Phase noise performance.

This article explains finding of power issues and the methodology of giving a suitable solution for performance stabilization of an ultra-wideband very high gain receiver with steep gain gradient. The origin of this problem lies in homodyning down conversion technique itself. Its LO is derived from input RF source. Varieties of frequency band limited equalizers like RC, RL and RLC are examined to overcome initial gain fluctuations at low frequencies as well as region based gain humps to reduce slope gradient. Thereby at the same time it helps to enhance practically achievable gain against theoretical gain at around highest frequencies by reducing power distribution among all harmonic and spurious components caused by lower frequency elements.