Some brief explanations

• This is a simulation of a basic radio interferometer. It consists of of two (or more) antennas placed in a row at specifiable distances. All antennas are parabolic dishes of the same diameter and work at the specified frequency. There also is the choice of a single antenna, for comparison.
• The instrument's configuration can be chosen from:
  • single dish. The source passes through the centre of the antenna beam (angle=0).
  • 2-dish adding interferometer. Both antennas point to where the source passes through.
  • 2 dish correlation interferometer. Both antennas point to where the source passes through.
  • N-baseline correlation interferometer. All antennas point at the source.
• The antenna pattern of a single dish is displayed by the green button antenna. One may choose between sinc(x) = sin(x)/x, tophat, Gaussian pattern. The Half Power Beam Width is computed from the wavelength and the antenna diameter. 1-D or 2-D .....
• Several simple sky sources are available, with a specifiable angular diameter: top hat: the surface brightness is constant across the source, sun: source with limb darkening or brightening, and various radial brightness profiles: triangle, gaussian, exponential, 1/r etc. A single 1-D source can be chosen, or a 2-D disc, as well as a pair of two sources, separated by a specified angle, and with a specified intensity ratio. The source surface brightness is displayed by the grey button source, and by a grey curve.
• The output button allows to display the numerical data of the results at the bottom of this page. Simply grab the text with the mouse, copy and paste it into a text editor window for further use and storage as a simple text file. This may be imported or read by a program of your choice for further display and analysis.

Here are links to more detailed explanations:
Radiation pattern of an aperture antenna
How an interferometer works
How phasing affects an antenna array

Instrument Configuration:
Single dish: drift scan 2-dish adding interf.: drift scan 2-dish adding interf.: tracking 2-dish: drift scan (Re,Im,V) 2-dish: drift scan (V, phase) 2-dish: tracking (Re,Im,V) 2-dish: tracking (V, phase) N-baselines: visibility function (tracking) N-baselines: Re, Im (tracking) N-baselines: V, phase (tracking)
frequency [GHz]
dish diam.[m]
HPBW 2.06°
Ind.Antenna Pattern: 1-D Sinc 1-D Gauss 1-D Tophat circular Sinc circular Gauss circular Tophat evenly illuminated circular dish
baseline [m]
resolution = fringe period 0.344°
8 16 32 64 128 256 512 1024 baselines up to m
max. resolution 500 λ = 0.115°
rec.image range 3.66°

Sky source:
1-D boxcar / top hat 1-D sun with limb darkening 1-D sun with limb brightning 1-D triangle 1-D gaussian Orion 1-D 1-D 1/r profile 1-D 1/r**1.5 profile 1-D 1/r**2 profile 1-D exp(-r) profile 1-D pair of boxcars / top hats 1-D pair of suns with limb darkening 1-D pair of suns with limb brightning 1-D pair of triangles 1-D pair of gaussians 2-D top hat disc 2-D sun disc limb darkening 2-D sun disc limb brightning 2-D triangle disc 2-D gaussian disc 2-D 1/r profile disc 2-D 1/r**1.5 profile disc 2-D 1/r**2 profile disc 2-D exp(-r) profile disc pair of boxcar/top hat discs pair of sun discs with limb darkening pair of sun discs with limb brightning pair of triangle discs pair of gaussian discs pair of Orion 2D
angular diameter [deg]
L/R intensity ratio
separation in RA [deg]
DEC(L)=0°, DEC(R)= [deg]

Display:
max.angle
max.u = max.baseline/λ







Visibility:

Mouse position: