Analysis of the PM and AM associated with the natural eigenfrequencies of spinning metallic and dielectric cylinders illuminated at high frequencies

Christensen, J.K.; Underhill, M.J.

doi:10.1049/cp:20040879

Cited by 4 publications

(2 citation statements)

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“…A continuous 77GHz signal from a 'phase-coherent' CW radar, when reflected from a smooth or rough spinning cylinder, is converted into a pulse train with a repetion frequency equal to the cylinder spin frequency [1,2,3,4]. The pulses look like those from a pulsar.…”

Section: Introductionmentioning

confidence: 99%

A rotating fan-beam radiation model for the pulse duration and frequency spectrum of pulsar radiation

Underhill¹

2016

2016 European Frequency and Time Forum (EFTF)

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The assumption of a rotating fan-beam of broadband RF radiation appears to fit the observed pulse length to period ratio and pulse amplitude statistics of some pulsars. Here an electromagnetic (EM) mechanism is proposed for the generation of the fan-beam. The radiation pattern is assumed to arise from coupled standing wave components at harmonics of the pulsar spin frequency in radiating layers of (ionospheric) plasma above and around the equator of the pulsar neutron star. The conductive plasma carries current which circulates the magnetic axis of the pulsar. The particle beams emitted from the poles can also act as secondary radiators for the pulse radiation generated by the equatorial layer currents. In this model the radiation is not directed along the magnetic pole axis but is at right angles to it. The frequencies of the multiple layers form a comb spectrum with components spaced at harmonics of the pulsar rotation frequency. The pulse length to period ratio can be argued to be related to the fundamental EM coupling coefficients first presented in [6].

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Section: Introductionmentioning

confidence: 99%

A rotating fan-beam radiation model for the pulse duration and frequency spectrum of pulsar radiation

Underhill¹

2016

2016 European Frequency and Time Forum (EFTF)

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“…The motivation was (and is) partly in our need for an autonomous Doppler evaluation target for millimeterwave radar work out in the field. The motivation was also partly in the recent series of interesting articles [4][5][6][7] where a quasimonostatic radar was used to experimentally study the frequencydomain behavior of radar returns from rotating long conducting cylinders. In particular, if possible we wanted to extend the audiofrequency range beyond values shown in [5] and, at the same time, to have a look at "flat," more disk-like targets.…”

Section: Introductionmentioning

confidence: 99%

The Doppler wheel revisited

Eskelinen

Ruoskanen

2008

IEEE Antennas Propag. Mag.

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Millimeter-wave radar returns from cylindrical targets, such as artillery shells or helicopter rotor shafts, can be experimentally evaluated with the classic Doppler wheel. This also is a simple autonomous calibration tool for radar development and field testing. However, the less-apparent wheel-return characteristics found in practice must be taken into account. Doppler spectra for speeds up to 3000 rpm measured with a Ka-band radar against a 100 mm-diameter flat cylinder are presented, showing a frequency range from 200 to 4200 Hz. Meaningful signal amplitudes were measured up to the rim-speed Doppler. Frequency components beyond the range defined by the local radial velocity of the illuminated portion were observed up to 2500 Hz. Miniature surface deformations increased the amplitude of the highest frequencies by 5-10 dB3. Simulated spectra agreed with measurement results at the higher Doppler frequencies, but a model based on Physical and Geometrical Optics failed to explain the low-frequency components.

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Doppler measurements of smooth and rough surface high frequency scattering from spinning steel cylinders

Christensen

Underhill²

2004

IEEE Aerosp. Electron. Syst. Mag.

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Preliminary measurement results gathered using a fully coherent 77GHz phase coded pulse Doppler polarimetric radar and investigating the electromagnetic signatures of electrically large spinning steel cylinders are presented. New and novel results showing the Doppler contributions due to dynamic rough and smooth surface scattering effects are discussed and analysed. In the latter case, signififant sideband conversion occurs together with a rapid fall off in the power density spectrum. Future work is proposed and discussed. A fuller analysis of these preliminary results and further results will be presented in due course.

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Analysis of the PM and AM associated with the natural eigenfrequencies of spinning metallic and dielectric cylinders illuminated at high frequencies

Cited by 4 publications

References 0 publications

A rotating fan-beam radiation model for the pulse duration and frequency spectrum of pulsar radiation

A rotating fan-beam radiation model for the pulse duration and frequency spectrum of pulsar radiation

The Doppler wheel revisited

Doppler measurements of smooth and rough surface high frequency scattering from spinning steel cylinders

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