Far zone radiation incorporates shadowing and radar scattering from fuselage and wings


Far Zone Radiation, RCS, and EMI/EMC
for Electrically-Large Platforms

XGtd is a general purpose ray-based electromagnetic analysis tool for assessing the effects of a vehicle or vessel on antenna radiation, estimating radar cross section (RCS), and predicting coupling between antennas. Based on techniques such as Geometric Optics (GO), the Uniform Theory of Diffraction (UTD), Physical Optics (PO), and the Method of Equivalent Currents (MEC), performance and memory requirements are less dependent on the electrical size of objects than full wave methods. This makes it ideally suited for applications with higher frequencies or very large platforms where requirements of a full physics method, such as Finite Difference Time Domain (FDTD), may exceed available computational resources. XGtd also includes a number of capabilities that extend well beyond standard ray-tracing codes to provide high-fidelity outputs that are tailored to its intended applications, including the following:

  • Far Zone Antenna Radiation for surface-mounted antennas
  • Monostatic or bistatic Radar Cross Section (RCS)
  • Creeping Wave Diffraction: high-fidelity field prediction in shadow zones 
  • Doppler for moving transmitters and receivers
  • Coupling between antennas (equivalent to S-parameters)
  • Wide range of outputs for predicted EM fields and channel characteristics

What’s New in XGtd

The latest release of XGtd includes new functionality for radar cross section (RCS) applications.  Highlights include:

  • New, more accurate model for RCS analysis based on Physical Optics (PO) and the Method of Equivalent Currents (MEC)
  • New output types for far zone RCS and antenna gain field points
  • Ray path visualization to far zone field points
  • Visualization of edges considered by the calculation to be part of curved surfaces

See the complete Latest Enhancements list...

Key Benefits


Far Zone Radiation for Platform-Mounted Antennas


Calculate far-zone antenna radiation patterns that incorporate the local effects of the platform.

Radiation from antenna on shuttle. Results agree with XFdtd full physics code.

Large Platform Simulations


XGtd’s methods are less strongly affected by the platform’s electric size than typical full wave techniques, allowing modeling of larger, more complex structures.

Local radiation on Navy cruiser

Radar Cross Section


The new MEC/PO model calculates monostatic and bistatic radar cross section with greater accuracy than either MEC or PO alone. Results include both co-polarized and cross-polarized returns. New outputs provide field data and allow visualization of ray paths to far zone RCS field points.

Backscatter from a simple Tomahawk missile validated against a full-wave FDTD model
XFdtd/XGtd Hybrid Capability for Higher Fidelity


Calculate antenna radiation patterns for complex antenna designs within XFdtd, incorporating all impedance, coupling and scattering effects. Import into XGtd to determine effects of placement on electrically-large platforms.

Helical antenna in XFdtd mounted on large satellite in XGtd

Coupling & Dominant Paths for EMI/EMC Assessment


Display dominant paths between transmitter and receiver locations; use to better understand propagation or determine methods to mitigate undesired interference or scattering.

Dominant paths and received power at second antenna

Specialized Anechoic Chamber Editor with RAM Materials


Use Anechoic Chamber Editor to set up and model test geometry and specialized materials within chambers. 

C-17 in large anechoic chamber

The full XGtd product, including its powerful graphical user interface, runs on the Windows XP, Vista, and Windows 7 operating systems, including 32-bit and 64-bit versions. The propagation analysis engine runs on both Windows and Linux operating systems and can take advantage of multiple processors to reduce the computation time.