Search

This paper presents a new wideband waveguide substrate integrated waveguide (SIW) coupler with maximum deviation of ±0.5 dB in a 7.5–12.25 GHz bandwidth (48% fractional bandwidth). Proposed coupler consists of the standard WR90 waveguide and single layer/double clad SIW printed circuit board (PCB) which is placed crosswise on the waveguide. Proposed three port coupler (isolated port was ended with match load) has a two coupling level (average of coupling in 8–12 GHz frequency range) of 43.2 and 58.3 dB, which is correspond with the hole diameter of 3.5 and 3 mm, respectively. The main contribution of this work is based on the hybrid techniques of SIW and RWG for coupler design in the high power microwave application. Validation of the simulation results with measurement one proves that the proposed X‐band waveguide to SIW coupler is a good candidate for use in high power industrial/commercial applications. [ABSTRACT FROM AUTHOR]

This paper deals with the design and fabrication of an unpretentious (single-layer, without any lump element) broadband (97%, 11.3–32.3 GHz) radar cross-section reduction (RCSR) modulated surface (MS). The proposed structure uses sinusoidal modulation gap sizes between square patches within square unit cells to form a phase gradient that plays an effective role in improving the RCSR bandwidth. An MS with dimensions of 250 × 250 mm2, consisting of 40 × 40 unit cells with a period of 6 mm printed on a RO4003C (lossy) substrate of 0.06λLF (λLF being the wavelength at the lower frequency) thickness, has been prototyped. The MS has square patch (SP) unit cells with seven different gap sizes. A genetic algorithm (GA)-based fine-tuning has been implemented to further increase the performances of the structure. Measurements on it have been conducted considering both mono- and bi-static arrangements and for oblique incidences for both TM and TE polarization tests. A good agreement between simulation and measurement results proves the validity of the design criteria. [ABSTRACT FROM AUTHOR]

In this paper, a low-cost, simple, and reliable bi-static radar cross-section (RCS) measurement method by using a historic Marconi set-up is presented. It uses a transmitting (Tx) antenna (located at a constant position, at a reference angle of θ = 0°) and a moving receiver (Rx) antenna. A time gating method is used to extract the information from the reflection in the time domain; applying time filter allows removing the antenna side-lobe effects and other ambient noises. In this method, the Rx antenna (on the movable arm) is used to measure the reflected field in the angular range from 1° to 90° from the structure (printed circuit board, PCB) and the reference configuration represented by a ground (GND) plane of the same dimension. The time gating method is then applied to each pair of PCB/GND measurements to extract the bi-static RCS pattern of the structure at a given frequency. Here, a comparison of measurement results is carried out at 18 and 32 GHz with simulation ones indicating successful performance of the proposed method. It can be used as a low-cost, reliable, and available option in future measurement and scientific research. [ABSTRACT FROM AUTHOR]