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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...
The virtual cathode oscillator (vircator) can be one of the most promising high-power microwave sources due to its conceptual simplicity, high-output power capability, and potential tunability. Microwaves can be generated when the current of an intense relativistic electron beam exceeds the space-charge-limiting current of the structure. In this case, a virtual cathode comprising an electrostatic...
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...
Magnetrons have been widely used over the years in a variety of high power microwave applications. Their high peak power as well as their compact configuration have made them suitable to airborne and spaceborne communication applications, radar systems as well as heating applications. One of the most common ways to extract microwave power from a magnetron is radially, by coupling the energy from at...
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...
Metamaterials are artificial assemblies of multiple structures arranged in periodic patterns, designed to have electromagnetic properties that are not found in nature, such as negative refractive index, permittivity or permeability. Such properties enable a number of novel applications such as cloaking and can be utilized to reduce physical size or enhance operation of well-studied devices such as...
A quantum dot mode locked laser can generate microwave frequencies, functioning as a photonic microwave oscillator. The advantages of this microwave oscillator include the compact size of the laser device, the low phase noise, the tunability of the output power and frequency as well as the high optical to electrical conversion efficiency. Despite the advantages of this oscillator though, a maximum...
Microwave signals can be photonically generated by a quantum dot, passively mode locked laser. The main advantages of using this microwave source configuration are the small size of the device (approximately 8000×300 microns at a frequency of 5GHz), the stable signal output with low phase noise, the reconfigurability (tunable output power and frequency by controlling the dc biasing) and high optical...
In this paper, a polarization reconfigurable microstrip antenna, for WLAN applications, is proposed. The antenna structure is based on a reconfigurable feed network, which drives a circular patch. The approach, presented herein, is based on electronically reconfiguring the phase difference, between the antenna's feeding ports, to achieve polarization diversity. The proposed antenna is designed and...
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