Chao Gu is a Research Associate in the School of Engineering and Digital Arts.



  • Gu, C. et al. (2018). Wideband high-gain millimetre/submillimetre wave antenna using additive manufacturing. IET Microwaves, Antennas & Propagation [Online] 12:1758-1764. Available at: https://doi.org/10.1049/iet-map.2018.5412.
    This paper presents a novel design of a wideband high-gain resonant cavity antenna (RCA) for millimetre and
    submillimetre wave bands, and its fabrication using additive manufacturing. The proposed RCA antenna consists of a partially
    reflecting surface and three impedance matching layers fed by a waveguide. Additive manufacturing (AM) techniques are
    utilized to fabricate the design operating at 30 GHz. Two fabrication techniques are assessed for printing the antenna. The
    first technique is based on printing a dielectric material and fully coating the parts with a metallic layer, while the second
    technique involves printing the parts in a single process using metal 3D printing. The first technique offers a lightweight
    solution while the second technique can print the whole model in one run. The antenna design is investigated by both
    simulations and experiments. The measured results show an 3dB gain bandwidth of about 10%, and high gain over 15 dBi
    for all the three resulting antennas. Good agreement between simulation and measurement is obtained. The antenna has a
    low cost and achieved good performance in terms of wide bandwidth and high gain, thus it is potentially useful for highspeed
    wireless communications at millimetre-wave and sub-millimetre-wave frequencies.
  • Gu, C. et al. (2017). 3D-Coverage Beam-Scanning Antenna Using Feed Array and Active Frequency Selective Surface. IEEE Transactions on Antennas and Propagation [Online] 65:5862-5870. Available at: http://dx.doi.org/10.1109/TAP.2017.2754400.
    This paper presents the design of a smart antenna that can achieve three-dimensional beam scanning coverage. The antenna consists of a novel planar feed array and a cylindrical active frequency selective surface (AFSS). First, an array fed metallic reflector is studied as a reference antenna to validate the beam scanning characteristics in the elevation plane. Then the AFSS is assessed through simulation and measurement results. Finally, the complete structure containing the planar collinear array and the AFSS is analyzed. A prototype at S-band has been designed, manufactured and measured. The resulting antenna is shown to be able to operate at the 2.4 – 2.5 GHz frequency band and switch beams in both the azimuth and elevation planes. In the azimuth plane, the proposed antenna is capable of sweeping beams towards different directions to cover a full range of 360˚. In the elevation plane, it can achieve beam steering within an angle range of +16˚/-15˚. The measured maximum gain of the antenna is 9.2 dBi. This is the first report of a low-cost 3D coverage beam scanning antenna based on AFSS.
  • Gu, C. et al. (2017). Frequency-Agile Beam-Switchable Antenna. IEEE Transactions on Antennas and Propagation [Online] 65:3819-3826. Available at: https://doi.org/10.1109/TAP.2017.2713978.
    A novel antenna with both frequency and pattern reconfigurability is presented. The reconfigurability is achieved by integrating an active frequency selective surface (AFSS) with feed antenna. The smart FSS comprises a printed slot array loaded by varactors. A novel dc biasing arrangement is proposed to feed the slots vertically so that the unwanted effects caused by bias lines are minimized. A monopole antenna is designed to illuminate the AFSS. The resulting structure can operate in a frequency tuning range of 30%. By reconfiguring the different sections of active FSS cylinder into a transparent or reflector mode, the omnidirectional pattern of the source antenna can be converted to a directive beam. As an illustration, half of the AFSS cylinder is successively biased, enabling the beam switching to cover the entire horizontal plane over a range of frequencies. An antenna prototype was fabricated and measured. Experimental results demonstrate the capability of providing useful gain levels and good impedance matching from 1.7 to 2.3 GHz. The antenna offers a low-cost, low-power solution for wireless systems that require frequency and beam reconfigurable antennas. The proposed design consumes about 1000 times less dc power than the equivalent narrowband beam-switching antenna design using p-i-n diode-loaded AFSS.

Conference or workshop item

  • Gu, C., Gao, S. and Sanz-Izquierdo, B. (2017). Wideband low-THz antennas for high-speed wireless communications. in: Electromagnetics in Advanced Applications (ICEAA), 2017 International Conference on. IEEE, pp. 141-145. Available at: https://doi.org/10.1109/APWC.2017.8062263.
    This paper presents a brief review of low THz antennas and discusses their corresponding manufacturing techniques. In addition, a new antenna is introduced for the 300 GHz frequency band. The design is an all-metal structure with interesting features such as compactness, high gain, and wide operational bandwidth. These characteristics make it a promising solution for future high-speed THz communication systems.
  • Gu, C., Gao, S. and Sanz-Izquierdo, B. (2017). Low-cost wideband low-THz antennas for wireless communications and sensing. in: 10th UK-Europe-China Workshop on Millimetre Waves and Terahertz Technologies (UCMMT), 2017. IEEE. Available at: https://doi.org/10.1109/UCMMT.2017.8068470.
    Terahertz technology is expected to provide a significant improvement in wireless system performance. A common assumption is that traditional microwave devices can be scaled down to operate at higher frequency bands. However, it can be a challenge to directly transfer the design methodology from microwave to THz band as the size of the devices becomes a few millimeter large. The reduced antenna size at the THz band limits the suitable fabrication processes. This paper reviews a wide range of THz antennas and their fabrication methodology. Then based on the resonant cavity antenna concept, an all-metal 300 GHz wideband high-gain antenna is designed and simulated. The presented metallic antenna is suitable to be fabricated using 3D printing techniques, which can lead to a low-cost, reliable solution for the emerging THz applications.