Initial docs for plane wave

docs/source/input_api.rst

@@ -222,6 +222,10 @@ Transmission Line
 -----------------
 .. autoclass:: gprMax.cmds_multiuse.TransmissionLine
 
+Discrete Plane Wave
+-------------------
+.. autoclass:: gprMax.cmds_multiuse.DiscretePlaneWave
+
 Excitation File
 ---------------
 .. autoclass:: gprMax.cmds_multiuse.ExcitationFile

docs/source/input_hash_cmds.rst

@@ -900,6 +900,23 @@ For example, to specify a z directed transmission line source with a resistance
 
 An example antenna model using a transmission line can be found in the :ref:`examples <example-wire-dipole>` section.
 
+#discrete_plane_wave:
+---------------------
+
+Allows you to introduce a discrete plane wave source [TAN2010]_. Plane wave sources are useful tool in multiple different scenarios of electromagnetic simulations, especially when the wave is emitted by a source that is quite far away from the target. The syntax of the command is:
+
+.. code-block:: none
+
+    #discrete_plane_wave: f1 f2 f3 f4 f5 f6 f7 f8 f9 str1 [f10 f11]
+
+* ``f1 f2 f3`` are the lower left (x,y,z) coordinates of the total field, scattered field (TFSF) box, and ``f4 f5 f6`` are the upper right (x,y,z) coordinates of the total field, scattered field (TFSF) box.
+* ``f7`` is psi the polarisation of the wave.
+* ``f8`` is phi the propagation angle (degrees) of the wave.
+* ``f9`` is theta the propagation angle (degrees) of the wave.
+* ``f10 f11`` are optional parameters. ``f10`` is a time delay in starting the excitation of the transmission line. ``f11`` is a time to remove the excitation of the transmission line. If the time window is longer than the excitation of the transmission line removal time then the excitation of the transmission line will stop after the excitation of the transmission line removal time. If the excitation of the transmission line removal time is longer than the time window then the excitation of the transmission line will be active for the entire time window. If ``f10 f11`` are omitted the excitation of the transmission line will start at the beginning of time window and stop at the end of the time window.
+* ``str1`` is the identifier of the waveform that should be used with the source.
+
+
 #rx:
 ----
 

docs/source/references.rst

@@ -23,6 +23,7 @@ References
 .. [PIE2009] Pieraccini, M., Bicci, A., Mecatti, D., Macaluso, G., & Atzeni, C. (2009). Propagation of large bandwidth microwave signals in water. Antennas and Propagation, IEEE Transactions on, 57(11), 3612-3618. (http://dx.doi.org/10.1109/tap.2009.2025674)
 .. [STA2017] Stadler, S. (2017). A Forward Modeling Study for the Investigation of the Vertical Water-Content Distribution of Using Guided GPR Waves (Master’s Thesis, Freiberg University of Mining and Technology, Germany) (https://app.box.com/s/h2n2ytsdllcm77du1o9lknumngmq8vq8)
 .. [TAF2005] Taflove, A., & Hagness, S. C. (2005). Computational electrodynamics. Artech house.
+.. [TAN2010] Tan, T., & Potter, M. (2010). FDTD discrete planewave (FDTD-DPW) formulation for a perfectly matched source in TFSF simulations. IEEE Transactions on Antennas and Propagation, 58(8), 2641-2648. (https://doi.org/10.1109/TAP.2010.2050446)
 .. [TEI1998] Teixeira, F. L., Chew, W. C., Straka, M., Oristaglio, M. L., & Wang, T. (1998). Finite-difference time-domain simulation of ground penetrating radar on dispersive, inhomogeneous, and conductive soils. Geoscience and Remote Sensing, IEEE Transactions on, 36(6), 1928-1937. (http://dx.doi.org/10.1109/36.729364)
 .. [TUR1987] Turcotte, D. L. (1987). A fractal interpretation of topography and geoid spectra on the Earth, Moon, Venus, and Mars. Journal of Geophysical Research: Solid Earth (1978–2012), 92(B4), E597-E601. (http://dx.doi.org/10.1029/jb092ib04p0e597)
 .. [TUR1997] Turcotte, D. L. (1997). Fractals and chaos in geology and geophysics. Cambridge university press. (http://dx.doi.org/10.1017/cbo9781139174695)