create the difference pattern for a monopulse radar, this is a good approach. Phase-difference couplers can be used to create beam tilt in a VHF FM radio station, by delaying the phase to the lower elements of an antenna array. More generally, phase-difference couplers, together with fixed phase delays and antenna arrays, are used in beam-forming networks such as the Butler matrix, to create a radio beam in any prescribed direction. See also Star coupler Beam splitter References Bibliography Stephen J. Bigelow, Joseph J. Carr, Steve Winder, Understanding telephone electronics Newnes, 2001 . Geoff H. Bryant, Principles of Microwave Measurements, Institution of Electrical Engineers, 1993 . Robert J. Chapuis, Amos E. Joel, 100 Years of Telephone Switching (1878–1978): Electronics, computers, and telephone switching (1960–1985), IOS Press, 2003 . Walter Y. Chen, Home Networking Basis, Prentice Hall Professional, 2003 . R. Comitangelo, D. Minervini, B. Piovano, "Beam forming networks of optimum size and compactness for multibeam antennas at 900 MHz", IEEE Antennas and Propagation Society International Symposium 1997, vol. 4, pp. 2127-2130, 1997. Stephen A. Dyer, Survey of instrumentation and measurement Wiley-IEEE, 2001 . Kyōhei Fujimoto, Mobile Antenna Systems Handbook, Artech House, 2008 . Preston Gralla, How the Internet Works, Que Publishing, 1998 . Ian Hickman, Practical Radio-frequency Handbook, Newnes, 2006 . Apinya Innok, Peerapong Uthansakul, Monthippa Uthansakul, "Angular beamforming technique for MIMO beamforming system", International Journal of Antennas and Propagation, vol. 2012, iss. 11, December 2012. Thomas Koryu Ishii, Handbook of Microwave Technology: Components and devices, Academic Press, 1995 . Y. T. Lo, S. W. Lee, Antenna Handbook: Applications, Springer, 1993 . Matthaei, George L.; Young, Leo and Jones, E. M. T. Microwave Filters, Impedance-Matching Networks, and Coupling Structures McGraw-Hill 1964 D. Morgan, A Handbook for EMC Testing and Measurement, IET, 1994 . Antti V. Räisänen, Arto Lehto, Radio engineering for wireless communication and sensor applications, Artech House, 2003 . K.R. Reddy, S. B. Badami, V. Balasubramanian, Oscillations And Waves, Universities Press, 1994 . Peter Vizmuller, RF design guide: systems, circuits, and equations, Volume 1'', Artech House, 1995 . Radio electronics Microwave technology Distributed element circuits