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!