Junction Circulators

Bosma, H.

doi:10.1016/b978-0-12-027906-7.50010-2

Cited by 15 publications

(10 citation statements)

References 80 publications

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“…For a considerable time galaxy rotation curves have been providing some of the strongest evidence for Dark Matter (DM) in the Universe (e.g., Freeman 1970;Rubin 1978;Bosma 1981). A long standing problem has been the derivation of the DM mass distribution from the observed rotation curves.…”

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confidence: 99%

Properties of Dark Matter Halos in Disk Galaxies

Jong¹,

Kassin

Bell

et al. 2004

Symp. - Int. Astron. Union

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We present a simple technique to estimate mass-to-light (M/L) ratios of stellar populations based on two broadband photometry measurements, i.e. a colour-M/L relation. We apply the colour-M/L relation to galaxy rotation curves, using a large set of galaxies that span a great range in Hubble type, luminosity and scale size and that have accurately measured HI and/or Hα rotation curves. Using the colour-M/L relation, we construct stellar mass models of the galaxies and derive the dark matter contribution to the rotation curves.We compare our dark matter rotation curves with adiabatically contracted Navarro, Frenk, & White (1997, NFW hereafter) dark matter halos. We find that before adiabatic contraction most high surface brightness galaxies and some low surface brightness galaxies are well fit by a NFW dark matter profile. However, after adiabatic contraction, most galaxies are poorly fit in the central few kpc. the observed angular momentum distribution in the baryonic component is poorly matched by ACDM model predictions, indicating that the angular momentum distribution is not conserved during the galaxy assembly process. We find that in most galaxies the dark matter distribution can be derived by scaling up the HI gas contribution. However, we find no consistent value for the scaling factor among all the galaxies.

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mentioning

confidence: 99%

Properties of Dark Matter Halos in Disk Galaxies

Jong¹,

Kassin

Bell

et al. 2004

Symp. - Int. Astron. Union

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“…According to the well-known expression [1], [2], the diameter of the ferrite disks planar resonators should be mm if . This result is close to that used above.…”

Section: Numerical Resultsmentioning

confidence: 99%

“…T HE CLASSICAL stripline circulator consisting of perpendicularly magnetized ferrite disks constituting, together with a circular strip conductor, two TM resonators, is known from the remarkable works of Bosma summarized in [1] and additionally described in details in [2]. The input characteristic impedance of this junction is several times smaller than the standard value of 50 and needs matching with quarter-wave transformers, which can ensure narrowband or wide-band operation in dependence of the design.…”

Section: Introductionmentioning

confidence: 99%

Inherently matched Y-junction stripline circulator

Ivanov

1997

IEEE Trans. Microwave Theory Techn.

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An operation principle based on the field-effect displacement phenomenon of the perpendicularly magnetized ferrite striplines constituting the Y-junction circulator is proposed. The experimental results are in agreement with the idea that the striplines of the junction act as half-wavelength transformers ensuring 5%-8% bandwidth of the investigated circulators in the S-band without external matching.

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“…The theory for microstrip circulator design is mainly based on Bosma's circulation conditions [1]. And in the condition equations, relative permittivity is instead by e ε , where ( )…”

Section: Minimized Circulator Structurementioning

confidence: 99%