A novel method for enhancing the directivity of coupled-line directional couplers is presented. In a coupled-line directional coupler formed on thin multi-layered substrates, it is difficult to match the coupled-line characteristic impedance with the load impedance. This impedance mismatch causes forward coupling in the directional coupler, thus degrading the directivity. This method utilizes reverse-phase forward coupling with an additional coupled line to cancel the undesired forward coupling due to the primary coupled line. It has been experimentally verified that the directivity of the proposed 20-dB coupler is increased by 13 dB at 840 MHz in comparison with the conventional coupler.
SUMMARYIn order to meet various requirements for the 5th generation mobile communication, a high SHF wideband massive-MIMO system has been widely studied which offers wide system bandwidth and high spectral efficiency. A hybrid beamforming configuration which combines analog beamforming by APAA (Active Phased Array Antenna) and digital MIMO signal processing is one of the promising approaches for reducing the complexity and power consumption of the high SHF wideband massive-MIMO system. In order to realize the hybrid beamforming configuration in high SHF band, small size, low power consumption and precise beam forming over the wide-band frequency range are strongly required for RF frontend which constitutes analog beam former. In this paper, a compact RF frontend module for high SHF wideband 5G small cell base station is proposed. This RF frontend module is prototyped. Various key components of the RF frontend module are fabricated in 15 GHz band, and measured results show that high RF performances are able to meet the requirements of RF frontend.
Abstract:A highly compact microstrip-fed planar monopole antenna is proposed. It consists of a radiation patch, four stubs and a truncated ground. The antenna exhibits dual-band operation with −10 dB return loss bandwidths 0.45 GHz (2.20-2.65 GHz) and 5.23 GHz (6.52-11.75 GHz) in the lower band and upper band, respectively. Simulated and measured results show this antenna is suitable for WLAN, UWB and other wireless communication applications.
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