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We propose a hybrid full duplex passive optical network with fusion of wavelength‐division‐multiplexing and orthogonal frequency‐division multiplexing (WDM‐OFDM) for a radio‐over‐fiber (RoF) system application. The key of the system is a tunable optical frequency comb (OFC) embedded cascading modulators and a parameter mixer. Moreover, 23 frequency components with 0.6 dB flatness generated by the OFC are used as light sources for each WDM channel. We utilize a 7.5 GHz OFDM wired signal and a 12.5 GHz OFDM wireless signal for downstream transmission and 10 Gb/s OOK (on–off keyed) signals for upstream traffic. Using polarization multiplexing technique, we extract a central optical carrier to bear the upstream signal so that no excess optical source is introduced into the ONU. Thus, the intricacy and costs of system are diminished. Moreover, successful transmission has been demonstrated since the bit error rates of the downstream and upstream signals are always under the adopted forward error correction limit. Furthermore, the proposed system can enhance power budget and reduce cost, which has a promising prospect for future wireless communication. [ABSTRACT FROM AUTHOR]

A novel broadband three‐input four‐output (3 × 4) Butler matrix (BM) without crossover is presented for the wider band operation. The proposed 3 × 4 BM is composed of three 3 dB branch‐line directional couplers, one T‐splitter power divider, and two 90° phase shifters. Unlike the traditional BM, the proposed BM network has successfully eliminated the crossover connection for simplifying the network, which operates in a wide operating range. For the validation of the design, a planar single‐layer 3 × 4 BM working at the frequency band of 1.69–2.69 GHz is designed, fabricated, and measured. The measurement result gives bandwidth up to 46% with return loss better than 14.3 dB at the full operating frequency band. [ABSTRACT FROM AUTHOR]

ABSTRACT A novel coupling matrix synthesis method for dual-band bandpass filter is presented in this article. The output admittance poles and zeros of the single-band filter prototype are firstly obtained and then transformed into dual-band prototype. Then the coupling matrix with predefined topology is optimized according to these poles and zeroes directly. This method can be achieved with no need to construct the characteristic function of dual-band filter and reconfigure the coupling matrix. Symmetric and asymmetric dual-band bandpass filter coupling matrix synthesis has been carried out to illustrate and validate this method. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:603-606, 2016 [ABSTRACT FROM AUTHOR]

ABSTRACT A compact microstrip lowpass filter (LPF) which consists of a meander line, a coupled line and two open stubs is proposed. The mechanism for reallocating filter transmission zeros and the design procedure are explained. The simulated and measured results demonstrate that this LPF provides compact size, low insertion loss, and wide stopband. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:367-371, 2015 [ABSTRACT FROM AUTHOR]