Angular spectrum simulation of X-ray focusing by Fresnel zone plates Angular spectrum simulation of X-ray focusing by Fresnel zone plates

Fresnel zone plate simulation dating, article versions

Compared with the standard version, the FZPA with alternating hex-cut zones had a decreased peak directivity of 0. V, Proceeding of the "Diffractive Optics ", Sept. But as with all scientific progress, experimentation will be the key. Measurements were performed and were found to match closely with the simulated results.

The aperture illumination was a problem because the same feed was used for all simulations despite it not providing dB edge illumination for all cases. For the case of square zones, approximations are required since the square boundaries do not coincide with the circular Fresnel zones.

Proposed topology mikey s hookup closed reviews on spirit be seen in Figure 1. The FZPA is much simpler to fabricate, has a reduced aperture thickness, is lighter weight, and is an overall lower cost antenna solution.

The performance of square FZPLs with these various zoning rules is then compared in the final section. A second disadvantage of the FZPA is its relatively large physical volume when compared with planar arrays.

Table 2 summarizes a selection of these simulated results where the xbdating of rotation angles go from outer zone to inner zone.

An open-ended WR28 waveguide with a ground plane around its aperture was used to feed the FZPAs and was placed at the lens focal point.

All the structures were simulated in the Ka-band, and measurements were performed to verify the simulations. It was found that focal distances below 0. In this way, the designer can effectively place the sidelobes in a desired location.

Currently we are considering perfect, flat metallic reflectors. In optics, this is called "blazing". When considering frequency hopping, it is very valuable. It also allows an appropriately patterned Fresnel reflector to be mounted flush to the side of a building, avoiding the wind loading that a parabaloid would be subject to.

Measurements were performed to verify the simulated results and showed good agreement. Several approaches suggest themselves if it is determined that the "specularity" of these surfaces needs to be increased. As the CMOS scaling continues, chip cost per area keeps increas- ing, rendering the bulky on-chip inductors increasingly costly.

There was work done in the 's using foam plastics as lenses: The smaller focal distance yielded a broader band response and a higher directivity at 30 GHz.

Numerical simulation of acoustic lenses based on Fresnel zone plate

It was also observed that slit- patterned FM layers exhibited better quality factors than blanket FM layers, leading to values comparable to that of the inductors without FM layer. A is the computed amplitude of the received signal.

Despite these tremendous advantages, they have not been widely used in the past. This was expected since the aperture size was also decreasing due to the relationship between the focal distance and the radii given in 1. Mixing the rotations from clockwise to counter-clockwise did not produce desirable results.

The result is that the effective f-number of a zone plate is lower than for the corresponding pinhole and the exposure time can be decreased.

There may be a typo left, but I don't think so. In these cases, the lens tends to behave more like a leaky-wave structure. Also, this new structure has an improved sidelobe level over the standard version.

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Peak Directivity Bandwidth To properly observe the variation in directivity with focal distance, the aperture size must remain constant while the focal distance decreased.

The derivation of this improved zoning rule is presented along with simulated results for some typical cases. This additional drop was thought to be related mostly to the aperture illumination effect since very little of the aperture was being illuminated at these small focal distances.

Rotation of AD through Pi radians is sufficient, as continued rotation only duplicates.

Design Fresnel zone plate antenna in HFSS.

The optimal hexagon was found to yield the least amount of impact to the directivity. Fresnel zone plate antenna, hexagon, lens antennas 1. If A represents a point on the square boundary and B, a point on the circular zone boundary, then one can define a maximum error A between the difference of a set of rays from the lens aperture to the focal point as: These items were not included in the original simulations.

However, if the rotation was not progressive, the sidelobe smearing would not occur. Young, Integrated waveguide slot antennas, Electron Lett 4 In this article, the hexagonal geometry is applied to the standard FZPA in a different manner.

The simulation is accurate, and produces the expected tight beams and sidelobes. Because of the different sizes of metal zone radii for the different focal distances, a direct comparison was only possible for the 3.

Introduction Fresnel zone plate lenses FZPLs have found many applications in both optical and microwave fields either as lenses to collimate energy or as antennas for high-gain applications [].

This leakage signal degrades the sensitivity of the receiver; moreover, it even saturates the receiver circuits in partial cases.

With a single zone, the 1. All dimensions are in meters, angles in radians, except for DG which is the off-axis pointer, and is in degrees.

Colwiz | Numerical simulation of acoustic lenses based on Fresnel zone plate - publication

It was found that rotations in the counter-clockwise direction produced the same results as those in the clockwise direction. The feed was modeled on its own and shown to have a peak directivity of about 7 dB and beamwidths that satisfactorily achieve a 10 dB edge taper on the aperture of the antenna.

Software testing[ edit ] A bitmap representation of a zone plate image may be used for testing various image processing algorithms, such as: Recently, however, the large area occu- pied by the inductors has emerged as yet another serious challenge. When the focal distance spacing reached 0.

It was found that the single metal zone with 1. The effect of FM material is different for the two types of inductors. Therefore, TX leak- age signals can be more comprehensively eliminated, which leads to higher grade isolation characteristics. When the same curves were generated without the ground-plane they increased monotonically.

Figure 7 shows an example of the FZPA with rotated hex-cut zones. MS ].

Figure 2 c illustrates this proposed structure. However, the maximum cross-polarization was still better than 40 dB down from the co-polarized maximum.