Metal Space Frame Radome

A metal space frame radome has metal members forming a geodesic dome over the antenna with dielectric panels stretched in triangles.
diel_dome.png
Dome using circular metal members (struts) and dielectric panels
refl_diel_dome.png
Radome from below showing the reflector located in the dome

When analyzed in GRASP (TICRA), the metal members are clustered together as a series of circular struts.  The dielectric panels are entered one at a time and then gathered into a scatter_cluster so that all panels can be operated as a single entity in the command list. Both the series of circular struts and dielectric panels are referenced to a dome coordinate system which allows rotation of the dome over the antenna. This rotation allows determination of reflector beam changes as it is scanned while keeping the antenna boresight on the z-axis.

A second type of space frame radome uses rectangular strut members.  These require that each strut have its own coordinate system in GRASP. This radome rotates the rectangular struts so that the narrow edge points radially to the center of the radome to reduce blockage.  The actual struts are trapezoidal which means the inner edge can be larger than the outer edge and reduce GRASP run-time, because currents are not excited on the edges with grazing incidence.
geodesic struts rect
Two triangular subdivision geodesic dome using rectangular members in GRASP

dielectric panels
Dielectric panels added between rectangular cross-section struts

panels and struts
Dielectric panels added to outside of struts

rect struts 3 div
Rectangular strut geodesic dome using 3 subdivisions

The following download contains DOS executables to generate GRASP tor file additions to modify the tor file of reflector for the metal space frame radomes: geodesic_domes. The download includes files of a GRASP example of a 200λ diameter reflector under a 300λ diameter geodesic dome radome.

geodesr.exe  generates geodesic dome using circular struts where the vertices location can be randomized.
geodespr.exe generates geodesic dome using trapezoidal struts with the narrow edge rotated toward the center of the dome including randomized vertices locations.
domecst.exe generates a dome using circular struts by using an input list of vertices location, strut endpoint list, and dielectric triangular panel endpoint list.
domerst.exe generates a dome using trapezoidal struts from an input list of vertices location, strut endpoints list, and dielectric triangular panel endpoints list.

The executables geodesr.exe and geodespr.exe output list files suitable for use in both domecst.exe and domerst.exe for input of geometry.