In this paper, a new frequency selective surface (FSS) is proposed, which is mainly applied to 5G communication. The equivalent circuit method is used to provide assistance for structural design. This structure can generate dual-frequency passbands that resonant frequencies are 28.1 GHz and 39.5 GHz. And it acquires large enough bandwidths to cover 27.5-28.35 GHz and 38.6-40 GHz which are bands of 5G communication. In addition, this structure is a multi-layer structure composed of one metallic layer and two dielectric layers, and its unit size is 0.56λ×0.56λ where λ is the wavelength corresponding to the first resonant frequency. Simulated results show that this structure has excellent filtering properties with respect to polarization stability as well as angular stability. Finally, the prototype of this structure is fabricated. The measured results and simulated results have consistent filtering characteristics within the tolerance of error.

This letter proposes a dual-stopband frequency selective surface (FSS) with tightly spaced frequency response characteristics. The metal layer of this FSS structure is composed of a metal strip of a bow-type ring and a metal strip of a square ring type, which forms the center symmetric ring structure. This dual-band FSS can achieve reflection characteristics at 6.29 and 8.35 GHz, which belong to C-band and X-band, respectively. In addition, two resonant frequencies can be independently controlled for good flexibility. This structure has excellent polarization stability and angular stability. Furthermore, a prototype sample of the proposed structure in this letter is processed and produced, and the test results are highly consistent with the simulation structure after being measured in a microwave anechoic chamber.

Monitoring of critical frequency variation in the ionospheric F2 layer (foF2) has lately received considerable attention for the frequency selection in skywave communication. Currently, both the deep learning and machine learning model have made a striking accomplishment in comprehending the ionosphere. In this letter, we utilize an Informer architecture to predict the foF2 parameter under the two scenarios in terms of the quiet space weather and storm events. The Informer method applied the past and present foF2 samples to capture time sequence processing characteristics, trained and tested for 2017-2018 years’ measurement samples at Beijing, China (40.3°N, 116.2°E). It is evident from the results that the Informer performed better than International Reference Ionosphere 2016, Elman network, long short-term memory, and bidirectional long short-term memory models. The Informer models extensively captured the correlation within the foF2 sequence features and better predicted it in storm events.

In this letter, a miniaturized frequency selective rasorber (FSR) based on complementary bandpass frequency selective surface (FSS) for fifth generation applications is designed. It is formed by the superposition of tortuous annular resistive layer and complementary bandpass FSS layer. The tortuous annular resistive layer consists of a regular octagonal patch and two bent metal rings. Four lumped capacitors and eight chip resistors are loaded to achieve impedance matching and wave absorption. In the bandpass layer, a complementary Jerusalem cross structure is adopted to realize electromagnetic wave transmission and structural miniaturization. The proposed FSR exhibits A-T-A filtering characteristics. The center frequency of passband is located at 2.6 GHz and transmission rate reaches 87.5%. Under 80% absorption rate, low-frequency absorption band ranges from 1.64 to 2.36 GHz, and high-frequency absorption band ranges from 1.64 to 2.36 GHz. Finally, a 500 mm × 500 mm prototype is fabricated, and the measured results are highly consistent with the simulated results.

This letter studies the impact of network-coded multiple access (NCMA) on the outage performance of full-duplex cooperative non-orthogonal multiple access (NOMA). In particular, we propose a network-coded cooperative NOMA (NC-CNOMA) strategy, under which user devices utilize physical-layer network coding (PNC) to demodulate signals with greater probability. The exact analytical expression of the outage probability is derived to evaluate the performance of the proposed scheme. The provided simulation results validate our analysis and the proposed NC-CNOMA scheme outperforms the conventional cooperative NOMA with regard to outage performance.