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A co-design dual-polarized patch antenna operating in dual compressed high-order modes and solar cells is proposed for green communication. The solar cell patch antenna is proposed for enhancing gain, wideband communication, and powering for wireless sensors. First, to enhance the gain of the antenna and the ability of optical energy harvesting, the antenna resonates at the high-order compressed modes. Secondly, the solar cell works in the direct-current loop, and the antenna works in the radio-frequency loop, separately. A differentially coupling-fed structure and two rows of vias are employed, which are beneficial to bandwidth and prevent the two loops from interfering with each other. Intrinsic isolation is achieved without any extra circuits. Next, a parametric study is exhibited as the antenna optimization guideline. By measuring the prototype experimentally performances, the design approach and the principle are validated. The measured results photoelectric experiment confirmed the ability of the solar cell antenna to convert luminous energy into electrical energy. In the desired operating band (4.8-5 GHz), the radiation performance of the proposed dual-polarized solar cell antenna is higher than 8.6 dBi for 5G communication.

This article presents a 2.4-4-GHz wideband 7-bit switch-type phase shifter (STPS) with a switch driver. Three switch-type phase shifting topologies are employed for the design of the phase shifter (PS), including the switched L/C structure, T-type structure, and high-/low-pass network. For minimizing the phase and amplitude deviations, an improved T-type structure with a switched filter structure has been proposed to boost the performance of the PS. Besides, a phase compensation cell also has been adapted to further decrease the phase error of the STPS. Based on the topology choice of each cell and the amplitude compensation among cells, a systematic design method is developed to extend the bandwidth of the PS. The proposed 7-bit STPS was implemented in the 0.5-μm GaAs pHEMT process. The measured root-mean-square (rms) phase error of the proposed STPS is less than 3.1° from 2.4 to 4 GHz and less than 1.5° at 2.8-3.7 GHz. The average insertion loss (IL) is 4.5-4.9 dB with an rms amplitude error of less than 0.34 dB. IP $_{{1,dB}}$ is about 30 dBm. To the best of our knowledge, this PS achieves the highest resolution and the lowest rms amplitude error among the published GaAs/GaN PSs over a similar frequency band. The IL, bandwidth, and rms phase error of the proposed PS also show good performance.

This article proposed a codesign of a power amplifier (PA) and a bandpass filter (BPF) named filtering PA using metal integrated and substrate integrated suspended line (MI-SISL). Two BPFs are designed separately as the input and output matching network to realize bandpass filtering response and good harmonic suppression at the same time. The BPF matching circuits are implemented using SISL-based dual-layer interdigital capacitors for miniaturization and SISL-based dual-layer spiral inductors for low loss. The suspended substrate of the PA is patterned according to the shape of the PA core circuit, which helps to reduce the circuit loss and improve efficiency. Moreover, the metal integrated technique is also proposed by replacing the top and bottom substrates of the conventional SISL structure with metal plates with good electrical and thermal conductivities for heat dissipation. A filtering PA on the MI-SISL platform at 0.9 GHz is fabricated and measured as a demonstration case. An ultrasmall size of 0.12 $λ_{{g}}$ x 0.07 $λ_{{g}}$ is achieved, where $λ_{{g}}$ is the guide wavelength at 0.9 GHz. To the best of our knowledge, this is the most compact filtering PA on the board level to date. In addition, a harmonic suppression level of 40 dBc in up to the fifth-harmonic frequency is achieved.

This letter presents an ultralow noise K-band low-noise amplifier (LNA) using substrate integrated suspended line (SISL) technology. A simplified, purely distributed parameter matching network is utilized for simultaneous noise and impedance matching. Different from standard chip-level circuits, a K-band LNA based on board-level platform with low-cost FR4 is proposed. Using the high-Q value of the SISL platform, this LNA shows the advantages of high-power gain, ultralow noise, and self-packaging. According to the measurement, the proposed LNA achieves a 27.7-dB small signal gain with 2.4-GHz 3-dB bandwidth (25-27.4 GHz) and noise figure (NF) of 1.0 dB with 20-mW power dissipation.

A dual-band multi-mode high gain stacked-patch antenna based on substrate integrated suspended line (SISL) is proposed for 5G applications. The proposed antenna comprises five low-cost FR4 dielectric substrate layers and ten metal layers with embedded air cavities. The driven patch generates TM10 mode and TM02 mode, and the other two modes are generated by etching the U-slot and horizontal slot on the driven patch to achieve dual-band. The stacked patch with the U-slot can suppress the radiation pattern split of TM02 mode, improve the antenna gain in the high-frequency band and generate radiation null to increase the out-of-band gain-suppression level. To verify this principle, the antenna is fabricated and measured. The measured results show good agreement with the simulated ones and the proposed antenna operates at 3.21-3.66 GHz and 4.75-5.40 GHz, which can cover the 5G communication band. The antenna has high efficiency. The maximum gains in the two bands are 9.12 dBi and 8.65 dBi, respectively.

In this letter, a voltage-controlled oscillator (VCO) with low cost, wide-tuning range, and low phase noise is proposed based on substrate integrated suspended line (SISL) technology. Benefiting from the weak coupling between half-wavelength resonators, the Q value can be improved, so as to reduce the phase noise of the VCO. By introducing a varactor in the high-Q resonator, a wide-tuning range is achieved. All the used boards choose FR4 material with very low cost. The designed SISL VCO has a tuning range of 380 MHz and has a phase noise of -122.81 dBc/Hz at a 1-MHz offset relative to the 5.88-GHz carrier. Compared with the existing board-level VCOs, this design features a wide-tuning range and low phase noise based on a low-cost platform.

A low-cost differentially-fed dual-mode multiple-input- multiple-output (MIMO) antenna is proposed for enhanced isolation and filtering response based on the substrate-integrated suspended line (SISL) platform. Stacked patches are placed above the driven patches to realize dual-mode performance and filtering response in the upper band. The stacked patches are widened and notched to enhance the isolation and the filtering response in the lower band. Eight metal stripes are set at both sides of the feed lines to enhance the frequency selectivity further. Compared with the conventional MIMO antenna based on patch elements, the isolation is enhanced by 7.6 dB, and the out-of-band suppression with 17.6 dB is achieved. To verify the design, a prototype is fabricated and measured. In a operating band of 4.8-4.96 GHz, maximum gain of 8.3 dBi, and isolation of 31.3 dB are realized. The filtering response is achieved by three broadside radiation nulls at 4.36 GHz, 4.62 GHz, and 5.08 GHz.

In this article, a novel design method of dual-band and dual-state (DBDS) Doherty power amplifier (DPA) is proposed. Considering the actual parasitic parameters, the DPA can be designed by using the impedance transformation of saturation and back-off points at dual frequency bands of DBDS as well as second harmonic matching. The DBDS DPA for dual-band (DB) 5G application, i.e., 3.4 and 4.9 GHz band are designed and implemented, for the first time, by using metal-integrated and substrate-integrated suspended line (MI-SISL) technology, which has advantages of high performance and self-packaging. The fabricated DBDS DPA achieves the measured 44 and 43.2 dBm saturated power at 3.4 and 4.9 GHz bands, respectively. For the 3.4 and 4.9 GHz bands, the measured drain efficiency (DE) is 70.7% and 70.4% at peak power levels and 38% and 42% at a 6-dB output back-off, respectively. When driven by a 20- and 100-MHz modulated signal with 6-dB peak-to-average power ratio (PAPR), the adjacent channel leakage ratio is better than -27 dBc at operating frequencies. The average output power of 38 and 37 dBm with an average efficiency of 37.9% and 40.9% is achieved at 3.4 and 4.9 GHz, respectively.

This paper presents a wide-band high-gain filtering antenna for 5G applications based on substrate integrated suspended line (SISL) platform. The filtering antenna mainly consists of a driven patch, a stacked patch, and a rectangular loop. By adding a rectangular loop to the conventional patch antenna, an additional resonance can be excited. Meanwhile, the frequency selectivity of the lower band is obtained due to the formation of a radiation null. Then, a patch is stacked on the driven patch, which also generates an extra resonance mode and a radiation null at the upper band-edge. Therefore, a bandpass filtering function is realized and the bandwidth is greatly improved with three resonance frequency points. The fractional bandwidth is from 4.28 to 5.34 GHz (22.04%), covering the specific 5G n79-band (4.45.0 GHz). Besides, the height of the antenna is only 0.080 (0 is the wavelength in free space of the central operating frequency), and the peak gain of the antenna is 10.4 dBi. It is worth mentioning that the whole design is low-cost since it is based on full FR4 substrates.