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We experimentally demonstrate for the first time the degenerate band edge (DBE) condition, namely, the degeneracy of four Bloch modes, in loaded circular metallic waveguides. The four modes forming the DBE represent a degeneracy of the fourth order occurring in a periodic structure where four Bloch modes, two propagating and two evanescent, coalesce. The DBE is associated with four Bloch eigenmodes...
The degenerate band edge (DBE) is a fourth order degeneracy occurring in a periodic structure at which four Bloch modes, both propagation and evanescent, coalesce. We experimentally demonstrate here for the first time the DBE dispersion in loaded metallic waveguides at microwave frequencies. The proposed waveguide in which DBE is observed here is designed by periodically-loading a circular waveguide...
We present results of simulation, fabrication, and testing of an S-band narrow-wall longitudinal slot antenna designed for high-power-microwave (HPM) systems. A key aspect of the proposed antenna structure is the use of longitudinal slots in the narrow-wall of a rectangular waveguide as elements of the slot array to enhance the power handling capability of the antenna. Cold test of the antenna showed...
Complementary-split-ring (CSR) Slotted Waveguide Antennas have been proven to be critical to high-power-microwave (HPM) systems, due to their compact size, high gain and high power-handling capability. CSR-SWA designs depend on highly accurate electromagnetic simulations that take geometric details into full account. Conventional antenna manufacturing approaches such as direct machining and platelet...
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...
This paper presents the design of a 5-element array consisting of four complementary split ring (CSR) slots on the narrow-wall of a rectangular waveguide and an H-plane-bend (HPB) radiator. Subwavelength CSR slots are recently proposed as elements of slotted waveguide antenna (SWA) arrays. Combining CSR slots on the narrow-wall of a rectangular waveguide with an HPB radiator provides significant size...
This work seeks novel designs of S-band high power microwave antennas based on rectangular waveguide narrow-wall longitudinal-aperture array structure. A narrow-wall slot-array is proposed to achieve higher gain. It consists of two identical narrow-wall slot-arrays with a common broad wall. A much more uniform aperture electrical fielded distribution is obtained, resulting in a higher gain for the...
In this work, an S-band slotted waveguide antenna (SWA) with optimized corrugations is presented. It is based on 10 identical longitudinal elliptical slots cut in one of the broadwalls of a WR-284 waveguide (a = 2.84″, b = 1.37″). The waveguide is shorted at one end and fed from the other, leading to a resonating SWA. Elliptical slots, which have no sharp corners, are known to be more suitable for...
Horn antennas are widely used in high power microwave systems, mainly due to their high power handling properties. Different variations of the traditional horn antenna geometry have been introduced in the past years to improve the radiation characteristics. Some of these techniques are used to alter the boundary conditions on the walls of the horn antennas allowing for the propagation of hybrid modes...
In this paper, a split-ring-resonator-loaded sub-wavelength waveguide with H-plane-bend (HPB) radiator structure is proposed. Improved matching is applied to minimize the reflected power at the input. This proposed waveguide is used as part of a high-power narrow-wall slotted waveguide antenna. The waveguide is loaded with an optimized split-ring resonator (SRR) array applying H-plane discontinuity...
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