A Compact Multiband mm-Wave Franklin Array With Frequency Scanning Capability

The following paper proposes a novel multiband series-fed microstrip array based on Franklin’s theory of collinear arrays (CoA). Conventional dipole elements have been replaced by rectangular patch elements (W/L 1) to increase the gain with a lower number of radiating elements. C-shaped Coupled line sections are used as delay line structures to compensate the phase differences among the radiating elements while eliminating the undesired radiation of conventional λ/2 delay line structures. The proposed delay line structures are also shortened compared to conventional transmission line feed networks. Radiating patches have been loaded with U slots for multi banding and decreasing the physical size of each patch to less than λ_g/4 . The ground plane is patterned for optimized matching. Results indicate a frequency beam scanning capability in range of 21~26 GHz, which makes it suitable for various mmwave applications, including drone detection radars. Radiation is broadside at 26 GHz, and the simulated gain is 10.2 dB at the same frequency. Simulation results have been processed by CST software and multiple computational methods is done to prove the validity of Franklin CoA theory on the proposed work.