Hongfu Meng

In this paper, the difference‐sum sidelobe suppression limitation in sequential rotation (SR) circularly polarized monopulse array is theoretically analyzed from a vector field superposition perspective. The SR architectures make the rotated radiators no longer identical, breaking the classical scalar array factor formulation and leading to angle‐dependent sidelobe elevation under amplitude tapering. To address this issue, an impedance‐redistributed SR feeding structure is introduced to facilitate a compact design with a reduced element spacing of 0.47 λ ₀ and achieve effective difference‐sum coverage, which ensures that the difference beam level remains higher than the sum beam. An 8 × 16 Ka‐band circularly polarized monopulse microstrip array is designed and fabricated. The measured results show that the antenna achieves a sum beam sidelobe level below –18 dB, difference‐sum coverage from −78.5° to 88° at 35.5 GHz, a 3 dB axial ratio bandwidth of 34 to 39 GHz (14%), and a peak gain of 20.4 dBic. The result validates the feasibility of the adequate coverage of the difference beam over the sum beam in SR feeding circularly polarized monopulse microstrip array.

In this letter, a D-band 8 × 8 substrate integrated waveguide (SIW) slot array antenna with wideband and high integration based on high-density interconnect (HDI) technology is proposed. To achieve broadband, a novel series-fed 1 × 8 slot linear array configuration is investigated. Through the optimized radiating slot geometry, integration of parasitic patches, and redesigned feeding layer layout, the presented structure achieves significant enhancements in both impedance bandwidth (IMBW) and radiation performance. Furthermore, the introduced surface-welded solder balls, serving as a replacement for conventional metal fences, effectively improves the |S₁₁| and gain flatness of the 8 × 8 array antenna. As a result, the antenna maintains excellent broadband characteristics even with half-wavelength spacing. Meanwhile, the antenna is manufactured using HDI technology, which further enhances the overall integration level of the antenna. Measured results demonstrate that the 8 × 8 slot array antenna achieves a -10 dB IMBW of 17.2% from 113 GHz to 134.6 GHz, a peak gain of 17.5 dBi at 120 GHz, a 3-dB gain bandwidth of 17%, and a 1-dB gain bandwidth of 13.8% from 115 GHz to 131.4 GHz.

In this letter, a stacked patch antenna loaded with a U-shaped slot is proposed for W-band active phased array applications. The proposed antenna comprises stacked patches and a substrate integrated coaxial line (SICL) feed, facilitating straightforward integration with the chips. A U-shaped slot is etched in the lower patch to improve impedance matching and enhance the beam scanning ability over a wide bandwidth. Sensitivity analysis further demonstrates that the U-shaped slot improves robustness against manufacturing variations. Based on the proposed antenna, a 2 × 8 array with a wideband differential SICL feeding network is designed, fabricated, and measured. The array achieves a measured −10 dB impedance bandwidth of 16.6%. A stable realized gain exceeding 12.2 dBi is observed within the frequency range from 90 to 103 GHz; the measured peak realized gain is 15.2 dBi at 94 GHz. Furthermore, the cross polarization discrimination over 36.9 dB is measured in both the H- and E-planes. The beam scanning capability (up to ±55°) of the array is also verified by active simulation.

A novel full W-band circularly polarized (CP) horn antenna is proposed. It contains a rectangular waveguide (RWG) for feeding, a waveguide polarizer based on evanescent and propagation modes, and a large pyramidal horn. The proposed polarizer is a ridge waveguide-to-RWG structure, where the ridge waveguide (RW) is the primary polarizer based on evanescent and propagation modes, and the RWG is the secondary one based on propagation modes. The polarizer overcomes the inherent limits of traditional ones that solely employ propagation modes, and achieves both broadband and miniaturization. With the proposed polarizer, a CP horn antenna is fabricated and measured. The entire antenna is a low-cost unibody construction, which avoids redundant splitting and assembly. Experimental results indicate that the proposed CP horn antenna performs well, with |S11| less than -14.2 dB, AR lower than 2.7 dB, and realized gain better than 18.1 dBi in the full W-band (75-110 GHz).

This paper introduces an active integrated fully-polarized architecture of one-dimensional (1-D) beam-scanning planar phased array based on linear arrays. The 1-D scanning capability of this architecture is realized based on compact linear arrays rather than individual units, which utilizes fewer active channels, leading to a substantial decrease in power consumption, heat dissipation requirements and overall system cost, particularly for large-scale phased array implementations. The fully-polarized waves are generated by superposition of two orthogonal linearly polarized waves. With the amplitude and phase of the two orthogonally polarized ports precisely controlled by active chips, the fully-polarized beam-scanning capability is achieved. The theoretical formulation of full-polarization beam-scanning synthesis of this architecture is derived. Then, a 16×24-scale active phased array constructed from 16 linear subarrays is designed, fabricated and measured to validate the effectiveness of the architecture. The operating bandwidth of the antenna covers 10.7 GHz to 12.75 GHz. And the prototype demonstrates a scanning range of ±45° across six typical polarization states, including linear x-polarization, linear y-polarization, linear ±45° polarizations, and both left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP). Moreover, employing the proposed architecture, the power of each unit in this 16×24 phased array is only 0.006w and the ratio of array unit numbers to active channel numbers is 12. Combining the full-polarization scanning capability with the high-gain, ultra-low power consumption and cost-effective attributes, the proposed active phased array positions it as a promising alternative for advanced satellite communication applications.

This paper presents an orbital angular momentum (OAM) multiplexing communication system employing active uniform circular arrays (UCAs) to achieve simultan

In this letter, a transmit-receive separation scheme of monopulse antenna applied in the terahertz (THz) band is proposed. This scheme does not require the circulator to achieve the separation between the transmitting and receiving channels, which reduces the loss and complexity of the monopulse antenna system, and greatly improves the integration of the antenna. Although still adopting five units to realize the function of monopulse, the presented scheme is distinct from the traditional five-unit scheme. In the proposed scheme, one antenna is placed at the center of the array to generate the transmitting sum (T-Σ) signal, and the other four antennas are placed at the top, bottom, left, and right of the central antenna, to generate the receiving sum (R-Σ) and receiving difference (R-Δ) signals at the azimuth (AZ) and elevation (EL) planes. A 220 GHz Cassegrain antenna, fed by the horn antenna array designed in the transmit-receive separation scheme, is fabricated and measured. The measured impedance bandwidth of all ports exceeds 10.9% (from 208 to 232 GHz). The isolation between the T-Σ and R-Σ ports is lower than -24 dB. The measured peak gains of the T-Σ and R-Σ beams is 38.4 and 37.7 dBi, respectively. The measured null depths of the R-Δ-AZ and R-Δ-EL beams are -23.1 and -25.6 dB, respectively. The experimental results are consistency with the expectation, and indicate the feasibility and superiority of the presented scheme in the THz band.

This letter presents a millimeter-wave (mmWave) compact broadband in-line microstrip-to-waveguide (M2W) transition based on the Single-side Defected Ground (SDG) method. The proposed SDG method achieves in-line M2W transition within a broadband through grooving the ground surface of the microstrip line (MSL) and shorting the end of the MSL. Furthermore, the SDG structure, aligned in the same direction as the MSL, effectively reduces the dimensions of the transition. The proposed structure of the in-line transition consists of a reduced-height waveguide and a probe with shorted terminals fed by a MSL. An in-line M2W transition operating at the Ka-band is analyzed and designed based on the proposed method. To evaluate the performance of the transition, a back-to-back structure is manufactured and measured. The measured results are in good agreement with the simulation results, confirming the effectiveness of the proposed method. The results demonstrate that the proposed transition reflection coefficient is better than -11 dB and the insertion loss is between 0.26-0.6 dB over the 25.3-41 GHz (47.4%).

This letter introduces the design of a highly efficient reconfigurable C/X dual‐band power amplifier (PA). Conventional dual‐band designs connect two amplifier branches for each band by a switch, whose transmitting losses will limit the efficiency of the PA. In alternative to the switching solution, the authors propose a novel design method using two branches of output matching networks (OMN) which the 5–6 and 8–12 GHz branch acting as active loads for each other, respectively. The band‐pass OMNs are applied, and parts of the passive matching components are replaced by transistors for channel selection. The proposed design has been simulated, implemented, and measured. The experimental results demonstrate a power added efficiency (PAE) of 45% at a pulsed output power (P_out) of 42 dBm in 5–6 GHz while a PAE greater than 39% at 42 dBm P_out in 8–12 GHz. Moreover, the second and third harmonics of both operating bands are compressed to −35 and −40 dBc, respectively. The proposed design technique addresses the challenges of low‐efficiency and lower‐band harmonic suppression in traditional dual‐band designs, making it suitable for application in next‐generation satellite communication and remote sensing systems.