Multi-GTD

Multi-GTD (Uniform Geometrical Theory of Diffraction) is a technique that uses ray-tracing to describe the radiation on an antenna, including phenomena that could generate interference. Grasp is a software that is able able to describe these reflections by associating them with an order. Zero order indicates that the ray has never been reflected, while order n means that it has been reflected n times. It is also possible to measure far-field radiation. 

Papers

Full-wave and multi-GTD analysis of the ice cloud imager for MetOp-SG: Multi-GTD and MoM (Method of Moments) were used for 50 GHz RF simulations on a parabolic reflector inside a semi-open cone with different geometries inside. The Multi-GTD was able to describe the main features of the graph at the frequency of interest, but it was necessary to complement with MoM at higher frequencies. Thus, it was concluded that in order to have a detailed description for high frequencies (>183 GHz) both MoM and Multi-GTD should be used. 

NOTE: The antenna is only 0.6 cm, so it could be unrepresentative for research purposes.

(Source: https://ieeexplore.ieee.org/document/7928453)

Combining GTD with MoM in analysing the scattering from the LICEF antennas on the SMOS satellite: For this research GTD is used to analyze the scattering on the solar panels of the SMOS satellite, which operates at frequencies near 1400 MHz and has an approximate size of 10m with its panels open. The satellite antennas are embedded in the satellite's solar panels, are circular and measure 145mm in diameter. MoM was preferred for the satellite body because it was relatively small compared to the wavelength of interest.

NOTE: The band used in this research is relatively far from the band of interest, on the other hand, the antennas could also be considered small.

(Source: https://ieeexplore-ieee-org.pucdechile.idm.oclc.org/document/4584973)

Utilization of the Geometrical Theory of Diffraction for antenna pattern prediction on Satellites: In this paper, the SYSTEMA-GTD computational tool (similar to Grasp) is used to simulate the mock-up response of antennas with different geometry and obstacles, in S and K band. For the analysis, GTD is compared with MoM and a comparison with Grasp is included at the end of the paper, obtaining similar results in all cases.

NOTE: This paper only includes analysis of antenna mock-ups, so it may not be of much interest.

(Source: https://ieeexplore-ieee-org.pucdechile.idm.oclc.org/document/6262301)

Method of moments (MoM) versus GTD for the analysis of aperture antennas: MATLAB is used to calculate from GTD and MoM the radiation pattern in conical horn antennas, using a frequency of 12GHz. The results obtained are then compared with the datasheets provided by the manufacturer. Finally, it is concluded that better results are obtained with GTD since it is able to detect the diffracted fields at the corners of the horn.

NOTE: The length of the horn is 0.0822m.

(Source: https://ieeexplore-ieee-org.pucdechile.idm.oclc.org/document/8809183)