1,680 research outputs found
Helical coaxial-resonator makes excellent RF filter
Isolation of closely spaced transmitting and receiving frequencies of an antenna without insertion loss by filtering the receiver input is accomplished by an inner conductor with two winding helices and an outer conductor of aluminum. A tuning slug is at either end of the inner conductor form
Optical Interference Suppression using MicroPhotonic RF Filter Structure
The impact of laser coherence noise on conventional photonic RF filters is investigated in this paper. In addition, a new microphotonic adaptive RF filter structure is proposed, which can simultaneously suppress the phased-induced intensity noise caused by optical interference. Results show that the coherence length of the laser light significantly degrades the RF frequency response of a photonic transversal RF filter, whereas the microphotonic RF filter has the capability of generating arbitrary transfer function with no phase-induced intensity nois
Reconfigurable photonic RF filter based on opto-VLSI processing
In this paper, a novel reconfigurable 5-tap photonic RF filter based on Opto-VLSI processor is proposed where an Opto-VLSI processor is used in conjunction with a 5-fibre Bragg grating (FBG) array to slice the spectrum of a broad band light source, thus achieving commensurate true-time delays and variable tap weights. The proposed photonic RF filterstructure is experimentally demonstrated by means of several examples which show the capability of the Opto-VLSI processor to synthesise transversal RF filter responses with adaptive weights
Reconfigurable RF-Waveform Generation Based on Incoherent-Filter Design
Radio-frequency (RF) waveform generators are key
devices for a variety of applications, including radar, ultra-wideband
communications, and electronic test measurements. Following
advances in broadband coherent pulsed sources and
pulse-shaping technologies, reconfigurable RF waveform generators
operating at bandwidths 1 GHz have become a reality. In
this work, we demonstrate reconfigurable RF waveform generation
using broadband spectrally incoherent optical sources. This
is achieved in two steps. First, we implement an RF incoherent
filter. The energy spectrum of the optical source is conveniently
apodized using a commercially available computer-controlled
D-WDM channel selector with 100-GHz resolution. The channel
controller provides high flexibility for shaping the optical source
energy spectrum and, hence, high reconfigurability capabilities in
terms of the RF filter. Second, we show that by applying a short
baseband electrical waveform to the input of the RF filter, the
output RF spectrum of the electrical signal is a mapped version of
the designed RF filter transfer function. Specifically, we illustrate
the capabilities of our technique by generating RF signals with
10 GHz bandwidth and tunable repetition rate. Finally, we
discuss how this method can be scaled up to the millimeter-wave
range with current technolog
Lessons learned from RF-Dipole Prototype Cavities for LHC High Luminosity Upgrade
The RF-Dipole Crabbing Cavity designed for the LHC High Luminosity Upgrade includes two higher order mode (HOM) couplers. One of the HOM couplers is an rf filter, which is a high pass filter designed to couple to the horizontal dipole modes and accelerating modes up to 2 GHz, while rejecting the fundamental operating mode at 400 MHz. The coupler consists of a high pass filter circuit where the rejection of the operating mode and transmission of HOMs are sensitive to dimensional deviations. An rf test box has been designed to measure the transmission of the rf filter in order to qualify the fabricated HOM coupler and to tune the coupler. This paper presents the measurements of the HOM coupler with the rf test box
Simulation and Measurements of HOM Filter of the LARP Prototype RF-Dipole Crabbing Cavity Using an RF Test Box
The RF-Dipole Crabbing Cavity designed for the LHC High Luminosity Upgrade includes two higher order mode (HOM) couplers. One of the HOM couplers is an rf filter, which is a high pass filter designed to couple to the horizontal dipole modes and accelerating modes up to 2 GHz, while rejecting the fundamental operating mode at 400 MHz. The coupler consists of a high pass filter circuit where the rejection of the operating mode and transmission of HOMs are sensitive to dimensional deviations. An rf test box has been designed to measure the transmission of the rf filter in order to qualify the fabricated HOM coupler and to tune the coupler. This paper presents the measurements of the HOM coupler with the rf test box
A Blind Interference Canceling Technique for Two-Stage Harmonic Rejection in Down-mixers
This paper presents practical experiments on a harmonic rejection down-mixer, which offers up to 75 dB of harmonic rejection, without an RF filter. The down-mixer uses a two-stage approach; the first stage is an analog multi-path/multiphase harmonic rejection mixer followed by a second stage providing additional harmonic rejection based on blind adaptive interference canceling in the discrete-time domain. The aim is to show its functional operation. The canceler cannot cope with DC offsets. The DC offsets are removed by highpass filters. The signal paths used to obtain an estimate of the interference must be designed to provide as much attenuation of the desired signal as possible. Front-end nonlinearities and DC offsets are discussed
Experimental Verification of a Harmonic-Rejection Mixing Concept using Blind Interference Canceling
Abstract—This paper presents the first practical experiments\ud
on a harmonic rejection downconverter, which offers up to 75 dB of harmonic rejection, without an RF filter. The downconverter uses a two-stage approach; the first stage is an analog multipath/ multi-phase harmonic rejection mixer followed by a second stage providing additional harmonic rejection based on blind adaptive interference canceling in the discrete-time domain. The aim is to show its functional operation and to find practical performance limitations. Measurement results show that the harmonic rejection of the downconverter is insensitive to frontend nonlinearities and LO phase noise. The canceler cannot cope with DC offsets. The DC offsets are removed by highpass filters. The signal paths used to obtain an estimate of the interference must\ud
be designed to provide as much attenuation of the desired signal as possible
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