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Antennas for High Power Microwave Applications

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Hilal El Misilmani
added 6 research items
Slotted waveguide antenna (SWA) arrays offer clear advantages in terms of their design, weight, volume, power handling, directivity, and efficiency. For broadwall SWAs, the slot displacements from the wall centerline determine the antenna’s sidelobe level (SLL). This paper presents a simple inventive procedure for the design of broadwall SWAs with desired SLLs. For a specified number of identical longitudinal slots and given the required SLL and operating frequency, this procedure finds the slots length, width, locations along the length of the waveguide, and displacements from the centerline. Compared to existing methods, this procedure is much simpler as it uses a uniform length for all the slots and employs closed-form equations for the calculation of the displacements. A computer program has been developed to perform the design calculations and generate the needed slots data. Illustrative examples, based on Taylor, Chebyshev and the binomial distributions are given. In these examples, elliptical slots are considered, since their rounded corners are more robust for high power applications. A prototype SWA has been fabricated and tested, and the results are in accordance with the design Objectives
This paper presents an inventive and simple procedure for the design of a 2D slotted waveguide antenna (SWA) having a desired sidelobe level (SLL) and a pencil shape pattern. The 2D array is formed by a defined number of 1D broadwall SWAs, which are fed using an extra broadwall SWA. For specified number of identical longitudinal slots in both dimensions, the desired SLL and the required operating frequency, this procedure finds the slots length, width, locations along the length of the waveguide, and offsets from its centerline. This is done for the radiating SWAs as well as the feed SWA. An example SWA with 8×8 elliptical slots is designed using this procedure for an SLL lower than −20 dB, where the design results are also reported in this paper.
Hilal El Misilmani
added a research item
This article presents a complete design procedure for planar slotted waveguide antennas (SWA). For a desired sidelobe level ratio (SLR), the proposed method provides a pencil shape pattern with a narrow half power beamwidth, which makes the proposed system suitable for high power microwave applications. The proposed planar SWA is composed of only two layers, and uses longitudinal coupling slots rather than the conventional inclined coupling slots. For a desired SLR, the slots excitation in the radiating and feeder SWAs are calculated based on a specified distribution. Simplified closed-form equations are then used to determine the slots nonuniform displacements, for both the radiating and feeder SWAs, without the need to use optimization algorithms. Using simplified equations, the slots lengths, widths, and their distribution along the length of the radiating and feeder SWAs can be found. The feeder dimensions and slots positions are deduced from the dimensions and total number of the radiating SWAs. An 8 × 8 planar SWA has been designed and tested to show the validity of the proposed method. The obtained measured and simulated results are in accordance with the design objectives.
Mohammed Husseini
added a research item
Slotted waveguide antenna arrays offer clear advantages in terms of their design, weight, volume, power handling, directivity and efficiency. Slots with rounded corners are more robust for high power applications. This paper presents a slotted waveguide antenna with elliptical slots made to one broadwall of an S-band rectangular waveguide. The antenna is designed for operation at 3 GHz. The slots length and width are optimized for this frequency, and their displacements are determined for a 20 dB sidelobe level ratio. Two rectangular metal sheets are then symmetrically added as reflectors to focus the azimuth plane beam and increase the gain.
Hilal El Misilmani
added a research item
Slotted waveguide antennas (SWAs) are widely used in high power microwave applications. In this paper, the slots displacements in broadwall SWAs, previously used to control the SWA sidelobe level ratio (SLR), are further investigated to also adjust the beamwidth of the SWA. A modified Taylor array design method is used to estimate the excitations of the SWA slots leading to independently controllable SLR and first-null beamwidth (FNBW). The slots displacements are then calculated from these excitations. An example is presented where the SWA has 7 slots and the proposed method is employed to find the displacements required for desired SLR and FNBW
Hilal El Misilmani
added a research item
This paper presents a procedure for the design of a 2D Slotted Waveguide Antenna (SWA) array having circular polarization. The 2D array is formed by a defined number of 1D branchlines broadwall SWAs, which are fed using an extra broadwall SWA. The SWA branchlines have cross-shaped slots that radiate with a circular polarization. The dimensions of these slots are optimized for best performance. The feed SWA is made with rectangular slots, which are designed to achieve a low SLL. An example SWA with 10 χ 10 slots is designed using this procedure, and the design results are reported in this paper.
Hilal El Misilmani
added a research item
A simple method for the design of rectangular slotted waveguide antennas (SWAs) with specified sidelobe levels is briefly described, and is used to design an example SWA with 7 broadwall elliptical slots and sidelobes lower than −20 dB. A special corrugation geometry is then added to the SWA, where the uniform height of the corrugations controls the SWA's operation frequency. This height can be changed by either pushing the corrugations through the non-slotted broadwall, or by implementing them on a conducting thin plate that can be replaced as needed, leading to some form of mechanical frequency reconfigurability.
Hilal El Misilmani
added 2 research items
This paper presents antenna designs with improved performance and characteristics for applications requiring high levels of microwave power. One such application is in the remote neutralization of landmines and unexploded ordnance, which is part of a wide research program on Humanitarian Demining. A description of this program is included in this paper. Two types of antennas are dealt with in this work: Vlasov and the slotted waveguide antennas. A Vlasov antenna with a curved cut is first introduced. This novel cut shape is more suitable for high power microwave (HPM) applications and results in increased antenna gain and good sidelobe level and half-power beamwidth. Bevel-cut and step-cut Vlasov antennas with optimized reflector position and angle are also reported. The optimized reflector is directly attached to the waveguide making the Vlasov antenna, which gives a simpler design. It also offers the advantages of a better control over the direction of maximum radiation, an increased antenna gain and a reduced half-power beamwidth. Corrugations are used inside slotted waveguide antennas in two configurations: one leading to a much smaller reflection coefficient at the antenna input, which is essential for HPM, and the second resulting in antenna size reduction by shifting down its operational frequency
This paper presents a Vlasov antenna with optimized reflector position and angle suitable for high power microwave applications. With the proposed configuration, the reflector is directly attached to the waveguide, which is an advantage and makes it simpler to radiate in the direction of the axis of the waveguide. Bevel-cut and Step-cut Vlasov antennas, designed for operation at 3 GHz, are used to validate the effect of the reflector. In addition to proper radiation of the direction of maximum radiation, the optimized reflector results in increased antenna gain and reduced half-power beamwidth.