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This paper demonstrates an optically controlled Co-Planar Waveguide (CPW) switch operating in the millimetre wave region. Full wave electromagnetic analysis used a multi-layer model to simulate the photoinduced plasmas and good agreement between measured and simulated results has been achieved. The insertion loss is less than 4dB and isolation is greater than 15dB from 32GHz-50GHz. This approach requires the use of 175mW of optical power at a wavelength 980nm, but it removes the need for bandwidth limiting electrical bias networks. Index Terms-Optically induced plasmas (OIP), Co-Planar Waveguide (CPW), millimeter wave (mmW), optical switch

This paper evaluates the performance of three-dimensionally (3D) printed spiral phase plates (SPPs) for enabling an orbital angular momentum (OAM) multiplexed radio system. The design and realization of the SPPs by means of additive manufacturing exploiting a high-permittivity material is described. Modes 1 and 2 SPPs are then evaluated at 15 GHz in terms of 3D complex radiation pattern, mode purity and beam collimation by means of a 3D printed dielectric lens. The results with the lens yield a crosstalk of −8 dB for between modes 1 and −1, and −11.4 dB for between modes 2 and −2. We suggest a mode multiplexer architecture that is expected to further reduce the crosstalk for each mode. An additional loss of 4.2 dB is incurred with the SPPs inserted into the communication link, which is undesirable for obtaining reliable LTE-based communications. Thus, we suggest: using lower loss materials, seeking ways to reduce material interface reflections or alternative ways of OAM multiplexing to realize a viable OAM multiplexed radio system.

We present a technique using a laser diode to actively tune a Franklin Array type antenna. We investigate the effect of directly illuminating the silicon dielectric to generate free charge carriers, increasing the conductivity of illuminated regions. Measurements and simulated results show reconfigurability of radiation patterns, resonant frequencies and polarization. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:994–998, 2016

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