Practical Microwave Beam Concepts
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Transcript of Practical Microwave Beam Concepts
Practical Microwave Beam Concepts
Jasper Nance
Outline
1. What is a microwave?
2. How do you make microwaves?
3. How do you send microwaves?
4. How do you recieve microwaves?
5. Can it be done?
What Are They?
How do you make ‘emHistorical Tubes
How do you make ‘emOperation
Phase 1: Production and acceleration of an electron beam
Phase 2: Velocity-modulation of the electron beam
Phase 3: Forming of a “Space-Charge Wheel”
Phase 4: Giving up energy to the ac field
How do you make ‘emOperation
Phase 1: Production and acceleration of an electron beam
Phase 2: Velocity-modulation of the electron beam
HF Electric FieldElectron Paths
No B Field
Small B Field
Too much B Field
Cutoff ( just right!)
How do you make ‘emOperation
Phase 4: The Electron takes the DC field energy and gives it to the AC field
Phase 3: Forming of a “Space-Charge Wheel”
Resulting Path of the Electron
Electron Bunching and Velocity Modulation in
response to AC field
How do you make ‘emOperation
Filament Leads
Resonant Cavities Anode
Cathode
Pickup LoopStrapping
How do you make ‘emPractical Considerations
Output WaveguideOutput LoopPossible Plate Construction
Patterns
a) slot- type b) vane- type c) rising sun- type d) hole-and-slot- type
How do you send ‘em?
Step1: Use waveguide horn to create a spherically diverging field
How do you send ‘em?
Step2: Feed it into a parabolic dish to create a planar field
Sidenote: Beam Dispersion
How do you receive ‘em?
Step1: Receive with another parabolic dish
How do you receive ‘em?
Step2: Use dish to concentrate signal onto receiving element
Helical
Dipole
How do you receive ‘em?
Step3: Couple Signal to a HF Bridge Diode
How do you receive ‘em?
Step3: Couple Signal to a HF Bridge Diode
How do you receive ‘em?
Step4: Feed into a buck (boost?) converter
Real World Example
Wifi signal powers bike lamp LED!