Rotman Lens Development at the Army Research Lab

Abstract

An electronic scanning antenna (ESA) that uses a beamformer for scanning the beam has the advantage of being able to form multiple beams for multimode, sharedaperture applications. This scanning approach is achieved at a reduced parts count for the antenna subassembly and therefore at a lower cost than approaches utilizing phaseshifting elements for controlling the beam. This paper discusses our efforts to realize such a beamformer using Rotman lens geometry and details some of the technologies we investigated as well as some engineering tradeoffs encountered.

Low profile arrays with integrated beamformers

“…As the Rotman is actually two mirror images that are secured together, the improvement in performance over the Aluminum lens is attributed to better contact achieved between the waveguide transmission lines and the cavity itself. The Aluminum lens was a far more rigid structure and the loss of continuity between the two halves is felt to be more pronounced accounting for the degraded patterns [1]. …”

“…This was for a proof of concept design, and less expensive plating would need to be used for any significant volume of production. The plating approach allowed a 60% reduction in weight; dropping it from 14.65 lbs to 6.05 lbs [1]. The radiated patterns for this Rotman lens were measured ( Figure 3) for comparison to the Aluminum structure.…”

Millimeter-wave phased-array antennas

“…Rotman lens array [14] is a low-cost, multi-beam solution but it is bulky and not suitable for monopulse and conical-scan applications.…”

Recent Trends in Computational Electromagnetics for Defence Applications

“…Defence applications span a broad electromagnetic frequency range. Radio frequency (RF) 1,2 , microwave antennas [3][4][5] , radars and spaceborne imaging 6,7 , terahertz and optical applications [8][9][10][11] are some of the major applications. An emerging area combining radio and optical frequencies, namely RF photonics, shows great promise for defence applications 12,13 .…”