A drone detection radar required a linear type rotary joint for scanning purpose at ku-band from 14.0-14.5 GHz. The linearly polarised antenna and transceiver used rectangular waveguide topology with dominant TE10 mode. An I-type linear rotary joint is designed for loss free connection between antenna and transceiver while scanning. Asymmetric to symmetric mode transitions are used along the rotary joint. TM01 mode is used along the circular waveguide in rotary joint. A single contactless junction is required for mode coupling instead of two junctions as in coaxial type linear rotary joint. Index Terms—Circular waveguide modes,