# Rotman lens

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A **Rotman lens** (sometimes referred to as a **Rotman-Turner lens**) is a [passive electronic component](/source/Passive_electronic_component) used for [beamforming](/source/Beamforming) in [radio frequency](/source/Radio_frequency) applications. The principle was first published by [Walter Rotman](/source/Walter_Rotman) and R. F. Turner in 1963,[1] and patented by Rotman the same year.[2]

The component allows multiple antenna beams to be formed without the need for [phase shifters](/source/Phase_shift_module). It consists of a range of input ports (also called beam ports) and output ports (also called array ports).[3] A signal applied to one of the input ports arrives at each of the output ports with a different [phase shift](/source/Phase_(waves)#Phase_shift). If the output ports are connected to individual antennas in an [antenna array](/source/Antenna_array), this allows shaping the beam in different directions by switching which input port the signal is sent to.[4] So-called dummy ports can be added to the design, which are [terminated](/source/Electrical_termination) to absorb fields that hit them, thus preventing reflections from the side wall of the lens.[3][5]

Rotman lenses can be constructed either from hollow conductive [waveguides](/source/Waveguide) or on a [stripline](/source/Stripline) or [microstrip](/source/Microstrip) substrate. They are commonly used for beamforming in [radar](/source/Radar) applications.[6]

## References

1. Rotman, W. & Turner, R. (November 1963). "Wide-angle microwave lens for line source applications". *IEEE Transactions on Antennas and Propagation*. **11** (6): 623–632. [Bibcode:1963ITAP...11..623R](https://ui.adsabs.harvard.edu/abs/1963ITAP...11..623R). [doi:10.1109/TAP.1963.1138114](https://doi.org/10.1109/TAP.1963.1138114). [ISSN 0096-1973](https://www.worldcat.org/issn/0096-1973)

1. ["Multiple beam radar antenna system"](https://patents.google.com/patent/US3170158/en). No. US3170158A. [Archived](https://web.archive.org/web/20240607134817/https://patents.google.com/patent/US3170158/en) 2024-06-07 at the Wayback Machine

1. ["Impact of Substrate Thickness on Rotman Lens Designs | Remcom"](https://www.remcom.com/resources/examples/impact-of-substrate-thickness-on-rotman-lens-designs). *www.remcom.com*. [Archived](https://web.archive.org/web/20240608093809/https://www.remcom.com/resources/examples/impact-of-substrate-thickness-on-rotman-lens-designs) 2024-06-08 at the Wayback Machine. Retrieved 2024-06-08.

1. ["Rotman Lens"](https://www.microwaves101.com/encyclopedias/rotman-lens). *Microwaves101*. [Archived](https://web.archive.org/web/20240607134818/https://www.microwaves101.com/encyclopedias/rotman-lens) 2024-06-07 at the Wayback Machine. Retrieved 2024-06-07.

1. Kilic, Ozlem & Weiss, Steven J. (June 2010). ["Rotman lens applications for the US Army: A review of history, present, and future"](https://ieeexplore.ieee.org/document/7909283). *URSI Radio Science Bulletin*. **2010** (332): 10–23. – via IEEE Explore.

1. ["Rotman Lens - Radartutorial"](https://www.radartutorial.eu/06.antennas/an75.en.html). *www.radartutorial.eu*. [Archived](https://web.archive.org/web/20240607134819/https://www.radartutorial.eu/06.antennas/an75.en.html) 2024-06-07 at the Wayback Machine. Retrieved 2024-06-07.

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