Product data
https://www.bksv.com/-/media/literature/Product-Data/bp1702.ashx
https://www.upc.edu/sct/en/documents_equipament/d_157_id-560.pdf
http://pcfarina.eng.unipr.it/Public/Standing-Wave/bruel_2013-11-20.pdf
http://www.ee.bgu.ac.il/~acl/Equip/NEXUS.pdf
http://www.softing.it/files/tesi_arcoleo.pdf
