ABSTRACT In this letter, a dual‐circularly polarized (dual‐CP) decoupled folded transmitarray antenna (FTA) is proposed, consisting of a transmissive metasurface (TMS), a reflective metasurface (RMS), and two magnetoelectric‐dipoles for LHCP and RHCP excitation. The unit cells in the TMS and RMS are capable of achieving dual‐CP decoupling. A low profile () is realized by incorporating the principle of anomalous reflection. The proposed FTA has been experimentally validated, and the measured results agree well with the simulations. The LHCP and RHCP beams are directed toward () and (), achieving peak aperture efficiencies (AEs) of 27.7%/28.3%. The 3‐dB gain and axial ratio bandwidths (BWs) for LHCP/RHCP beams are 24.8%/23.8% and 29.3%/27.9%, respectively. This work integrates dual‐CP decoupling into an FTA, featuring high AEs, wide BWs and a low profile, enabling independent beam pointing for dual‐CP satellite communication scenarios.
ABSTRACT In this article, an effective self‐decoupling method based on magnetic current coupling cancellation is presented to facilitate the isolation improvement of a closely spaced E ‐plane coupled microstrip patch antenna (MPA) array. By introducing three short‐circuit vias to the antenna element, the electric field intensities along the radiating edges of the antenna element can be effectively regulated. The coupling from the radiating edges of the active antenna element cancels out each other to achieve high port isolation. A mirror‐arranged two‐element transceiver MPA array with center‐to‐center spacing of ~0.33 λ 0 and edge‐to‐edge spacing of 0.05 λ 0 is fabricated and measured. The measured results exhibit a port isolation level of more than 41 dB over the −10 dB operating bandwidth, and a maximum level of 71 dB is observed. A prototype of the developed self‐decoupling MPA array was fabricated and measured; good agreement between the simulated and measured results was achieved.
ABSTRACT This letter presents a 0.2–7‐GHz 10‐W three‐stage gallium nitride (GaN) thic microwave integrated circuit (MMIC) non‐uniform distributed power amplifier (NDPA) for the next‐generation wireless communications. An impedance‐enhanced artificial transmission line (IE‐ATL) based on the coupling effect is proposed to enhance the equivalent characteristic impedance, thereby improving the efficiency while preserving the high current‐handling capacity required by the large‐periphery transistor. The impedance characteristics of the IE‑ATL are analyzed from both time‑domain and frequency‑domain perspectives. The die area is as small as 7.41 mm 2 . Continuous‐wave (CW) mode performance evaluations in 0.2–7 GHz demonstrate a saturated output power ( P SAT ) of 40.1–41.2 dBm, a power‐added efficiency (PAE) of 34.1%–46.7%, and a power gain ( G P ) of 28.3–31.2 dB. Benefiting from the proposed IE‐ATL, the presented NDPA achieves a superior broadband figure‐of‐merit (FOM) compared with reported counterparts.
ABSTRACT A circularly polarized (CP) microstrip composite right/left‐handed (CRLH) leaky‐wave antenna (LWA) with wide‐angle scanning capability is proposed. The antenna is based on a microstrip transmission line that integrates patch, metallic via, and folded branches for miniaturization. The left‐handed and right‐handed parameters generated among the branches, patch, and via are balanced, thereby eliminating the OSB effect. A prototype was fabricated and tested, and the unit cell features a compact size of 0.79 λg × 0.45 λg. Measurement results indicate that the antenna achieves a wide scanning range from −68° to +34° across 9.5–12.5 GHz (27.3%). The antenna achieves a circularly polarized beam‐scanning range from −30° to +10° over 10.3–12.0 GHz (15.2%), and the maximum gain reaches 15.2 dBi with smooth variation over the operating band. These characteristics render the proposed antenna well suited for satellite communication applications.
ABSTRACT In this letter, a reflective‐type voltage‐controlled oscillator (VCO) is proposed based on a compact shielded eighth‐mode substrate‐integrated waveguide (EMSIW) tunable cavity. The varactor diode is conveniently integrated at the apex of the EMSIW cavity, where the electric field is strongly concentrated due to the open resonator structure. This integration enables a broad frequency tuning range and compact size of the VCO. The reflective‐type VCO using EMSIW is designed, fabricated, and measured. Measurement results show that the VCO covers a tuning range from 10.12 GHz to 11.06 GHz. The output power ranges between 3 dBm and 6.5 dBm, while the phase noise remains better than − 97.5 dBc/Hz@1 MHz offset, with most values around − 105 dBc/Hz@1 MHz. Owing to its compact size, wide tuning range, and low phase noise, the proposed VCO is a promising candidate for X‐band frequency synthesizers in radar systems, satellite communication, and microwave links.
