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In this letter a W-band small-size low sidelobe level (SLL) 6 × 16 microwaveguide slot array antenna is proposed based on the silicon micromachining technology. The feeding network within the limited available area consists of several stages of equal T-junctions and TE120-mode-cavity dual-layer power dividers able to build the desired tapering power distribution over a relatively wide bandwidth. The TE120-mode-cavity dual-layer power divider is at the end of the feeding network, which can implement the layer-to-layer transition and the power division simultaneously. Thus, the whole size of the array antenna can be reduced by about 25% compared with the conventional five-stage tree-like feeding network. The overall antenna size is 60 mm × 20 mm × 1.85 mm. The measured maximum gain is 26.1 dBi at 94 GHz, and the corresponding radiation efficiency is 69.2%. The measured SLL in E-plane is below than −18.5 dB within the frequency band from 92 to 96 GHz. [ABSTRACT FROM AUTHOR]

A millimeter-wave near-field-focused (NFF) full 2-D frequency-scanning antenna array is presented in this article. The proposed antenna is achieved by combining an NFF ridged-waveguide slot array with a double-layer folded focused progressive feeding network. The linear ridged-waveguide slot array antenna is designed with a height-modulated ridge to focus on the power in one direction. The folded feeding line with different length is used to generate the desired focused phase and frequency-dependent progressive phase shift in the other direction. In this case, as the working frequency is swept in the considered range, the inherent frequency-dependent behavior of the linear NFF leaky-wave antenna (LWA) allows a single-scanning sweep in one direction, whereas the focused progressive feeding network ensures multiple-scanning sweeps in the other direction. A full 2-D electronic scanning with no coverage blindness in the scanning area is achieved. To the best of our knowledge, the proposed NFF antenna array is the first design to achieve the full 2-D scanning focus in the near-field (NF) region only by sweeping the frequency, which means that the testing information in the NF region can be directly obtained with a certain band of frequency. This type of antenna is a good candidate in NF fast-scanning applications, e.g., electromagnetic imaging/detecting systems. [ABSTRACT FROM AUTHOR]

A W-band decoupling structure sandwiched between a pair of high-gain step-profiled horn array antennas using the silicon micromachining technology is proposed. To suppress the surface wave, 18 choke slots with a depth of one quarter wavelength at 94 GHz are arranged in a triangular-grid array and the isolation can be averagely improved by about 7 dB with a range of 2–20 dB. This decoupling structure and two W-band coplanar array antennas are fashioned and fully integrated together by the silicon micromachining technique. Five 400 μm thick and one 650 μm thick silicon wafers are utilized and the total thickness of the antennas is 2.65 mm. Thanks to this technology, light weight, compact size, and high integration of the decoupling structure and array antennas can also be achieved. Additionally, the two array antennas share a common ground plane within a small edge-to-edge spacing of 6.05 mm where TM surface waves exist. Experimental studies validate the performance of the proposed triangular-grid choke slot array. [ABSTRACT FROM AUTHOR]

A wideband air-filled plate array antenna with multistage impedance matching operated in $D$ -band is proposed in this article. To achieve the wide bandwidth, three stages of impedance matching are introduced in the $2\times 2$ subarray, including the step-profiled horn element, the step-profiled power divider cavity with two resonant points, and a modified E-plane bend transition. The integrated step-profiled horn with simple configuration can realize broadband matching. Wideband T-junctions are combined together to form a corporate feeding network. Essential matching pins are introduced to break through the upper bandwidth restriction of the feeding network. In addition, the square aperture shape of the horn element and the air-filled feeding structure contribute to the high radiation efficiency of the proposed array. To satisfy the fabrication tolerance, the MEMS micromachining technology with a high etching precision is utilized. The experimental results show a wide 1 dB down gain bandwidth of 23.54%. The maximum gain is 33.24 dBi and the peak efficiency is 70.91%. [ABSTRACT FROM AUTHOR]

A wideband low-profile monopulse feeder at the W-band based on the silicon micromachining technology is investigated in this letter. The proposed monopulse feeder consists of four stepped horn elements as the radiating antenna array and four Magic-Tees as the comparator network for generating SUM and DIFF beams. In order to achieve the features of wide working bandwidth and low profile, a series of special structures are employed, such as a ridged structure and a metallic reduced-height waveguide, in Magic-Tees. The total thickness of this feeder is 2.65 mm (0.80λ), which includes six metallic layers. Then, the feeder is fabricated and experimented. This feeder has a working bandwidth of 21.7% (from 80.4 to 100 GHz) for ports 1 and 2, while a working bandwidth of 15% for port 3. More than 13.5 dBi is maintained for the gain of SUM patterns, and all gain ratios of SUM and DIFF beams are within 3.2 dB in the working bandwidth. The result indicates that this kind of feeder can be an excellent candidate for the W-band high-resolution system. [ABSTRACT FROM AUTHOR]