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  • mbenkerumass 5:00 am on March 28, 2020 Permalink | Reply
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    Ray Tracing Examples (1) Curved Mirrors 

    The following ray tracing examples all utilize Fermat’s principle in examining ray traces incident at a mirror.

    Example 1. Draw a ray trace for a ray angled at a convex mirror.

    The ray makes a 40 degree angle with the normal of the mirror at the point of incidence. In accordance with the law of reflection (Fermat’s Principle), the ray will exit at 40 degrees on the other side of the normal.

    op12

     

    The above example shows a single ray at an angle. Often, rays are drawn together in a group of parrallel rays. This example shows how an incident set of parallel rays will no longer be parallel when reflected by a non-uniform (not flat) mirror surface.

    op6

     

    This example brings up an important concept that happens especially with concave mirrors. Two rays drawn seem to be directed towards the same point, known as the focal point. A focal point however is only consistent for smaller angles. The third ray at the bottom makes a 55 degree incident angle with the normal of the surface. The reflected ray is also 55 degrees separated from the normal but is directed to the other side of the normal. The ray does not converge at the focal point as the others do. This effect is known as an aberration and may be discussed further at length in a later article.

    op7

     

    This example makes use of the above concept of focal point. An object placed at the focal point will not make an image at the focal point. This is useful if for instance, some type of lense or collecter should be placed at the focus of the mirror. This can be done without worry for it causing disturbances to the image that is formed at the focal point by the reflected rays.

    op8

     
  • mbenkerumass 5:00 am on March 13, 2020 Permalink | Reply
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    DeBroglie Relations and the Scale of Quantum Effects (MIT OpenCourseWare) 

    Assignment Sheet MIT OpenCourseWare – Quantum Physics I

    debroglie22333333333

    qmscan1

    PDF of solutions

    Barton Zwiebach. 8.04 Quantum Physics I. Spring 2016. Massachusetts Institute of Technology: MIT OpenCourseWare, https://ocw.mit.edu. License: Creative Commons BY-NC-SA.

     

     
  • mbenkerumass 5:00 am on March 11, 2020 Permalink | Reply
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    Ray Tracing with Snell’s Law – Optics, ECE591 

    Of the four ways of manipulating light, these examples employ shaping of a lens and the refractive index to change the path of a ray.

    591-1

    591-2

    591-3

     
  • mbenkerumass 6:00 am on February 28, 2020 Permalink | Reply
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    Tape Measure Yagi Antenna 

    Radio Club Meeting – Tape Measure Yagi build

    image3image2image160082311118__8CCDCFDA-BFA7-4E2D-8351-9F4533FC0B00

     
  • mbenkerumass 9:00 am on February 3, 2020 Permalink | Reply
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    028/100 VSWR Circles on the Smith Chart 

    Example 3.5-2B: Show the direction of movement on the Smith Chart when adding a series or shunt element to an impedance.

    Shunt Inductor:

    027-1

    Series Inductor:

    026-4

    Shunt Capacitor:

    027-2

    Series Capacitor:

    028-1

    Series Resistance:

    028-2

    Shunt Resistance:

    028-3

    Shunt Transmission Line:

    028-5

    Series Transmission Line:

    028-4

     
  • mbenkerumass 9:00 am on February 2, 2020 Permalink | Reply
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    Microstrip Stub Low-Pass Filter (10 GHz) 

    This is a 10 GHz Stub Low-pass filter, made using ADS.

     

    First, build the component using the ADS DesignGuide/Smart Component Passive Circuit tool.

    stublp1

     

    This is the original, equation-based simulation.stublp2

     

    This is the substrate used for the Low-pass filter.

    stublp3

     

    This is the Momentum simulation of the layout component.stublp4

     

    This is the layout component for the 10 GHz Stub Low-pass filter component.

    stublp5

     
  • mbenkerumass 9:00 am on January 27, 2020 Permalink | Reply
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    Messing with Substrates (10 GHz bandpass filter) [silly] 

    In this post we will take a reasonable 10 GHz bandpass filter (at least for a new grad student) and see how a new substrate will change how this filter works.

    This is the original bandpass filter with the standard substrate:

    messybp2

    messybp1

    If you can read the numbers on the above pic, you could also build this filter. Let’s get a better picture of what the substrate is for the original circuit:

    messybp3

     


    Let’s try a silicon dielectric, shall we?

    messybpsilicon

    One thing is for sure – it’s not a bandpass filter anymore.messybpsilicon2

     


    Let’s add a 20 mil Indium conductive layer below the dielectric:

    messybpindium

    Voilà! It’s centered at 8 GHz! Brilliant!

    messybpindium2

     


    Here’s a thought – how well does your bandpass filter work underwater?

    messybpwater1

    It looks like your bandpass filter might give you a little gain there at some frequencies in water!messybpwater2

     

     
  • mbenkerumass 9:09 pm on January 26, 2020 Permalink | Reply
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    Microstrip Lange Coupler (5 GHz) 

    The Lange Microstrip (quadrature) coupler is known for it’s low loss, wide bandwidth and compact layout. Similar to other couplers, it consists of an isolated port, through port and coupled port.

    You can build a microstrip Lange coupler using the DesignGuide tool in ADS:

    langec0

     

    These are the results for the equation-based simulation. These results admittedly look considerably better.

    langecoupler2

     

    This is the substrate used:

    langecoupler1

     

    These are the results for the momentum simulation. Admittedly, some tuning would improve this considerable.

    langec3

    And here is the layout component:

    langec4

     
  • mbenkerumass 9:00 am on January 19, 2020 Permalink | Reply
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    027/100 Shunt Reactance on Smith Chart 

    Example 3.5-2A: Measure the effect of susceptance on Smith Chart impedance matching.

    First, build the circuit and run the Smith Chart Matching tool.

    026-3

    A shunt capacitor moves in a clockwise direction across the smith chart tool:

    027-2

    Also note that a shunt inductor moves counter-clockwise across the smith chart tool:

    027-1

     
  • mbenkerumass 6:00 am on January 15, 2020 Permalink | Reply
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    Microstrip Double-Stub Load Matching 

    The following matches a 50 Ohm line to a 100 Ohm load at 10 GHz using a double-stub component. This was designed using the ADS passive circuit DesignGuide tool. This method is a great alternative to using the Smith Chart matching tool for lumped elements if you need a microstrip line for matching.

    Circuit:

    dsmat1

    Substrate:

    dsmat2

     

    Momentum simulation result (can be tuned to center better at 10 GHz):

    dsmat3

    Layout component:

    dsmat4

     

     

     
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