1. Fundamentals of Microwaves
1.1. Core Properties
Microwaves are electromagnetic waves characterized by their shorter wavelength. Their fundamental properties dictate their use and behavior in various systems:
- They radiate electromagnetic energy.
- They travel in a straight line and are not reflected by the ionosphere.
- They are reflected by conducting surfaces.
- They are susceptible to attenuation over shorter distances.
- Microwave currents can flow through a thin layer of a cable, a phenomenon known as the Skin Effect.
1.2. Advantages and Disadvantages
| Advantages | Disadvantages |
| Larger Bandwidth: Supports transmission of more information, ideal for point-to-point communications. | High Equipment Cost: Installation and component costs are significant. |
| Higher Antenna Gain: More focused signal transmission and reception is possible. | Bulky Components: Equipment can be hefty and require considerable space. |
| Increased Data Rates: Direct result of the larger available bandwidth. | Electromagnetic Interference: Susceptible to interference from other sources. |
| Reduced Antenna Size: Higher frequencies allow for smaller, more compact antennas. | Dielectric Property Variation: Properties can change with temperature fluctuations. |
| Low Power Consumption: Higher frequency signals require less power. | Inherent Power Inefficiency: Conversion of electric power can be inefficient. |
| Reduced Fading: Line-of-sight propagation minimizes signal fading effects. | |
| Effective Radar Reflection: Provides a good reflection area for radar systems. | |
| High-Capacity Communications: Enables high-capacity satellite and terrestrial links. | |
| Miniaturization: Low-cost, miniature microwave components can be developed. | |
| Spectrum Usage: Offers a wide variety of applications across all available frequency ranges. |
1.3. Key Applications
Microwaves have a vast and diverse range of applications across numerous fields.
| Category | Specific Applications |
| Wireless Communications | Long-distance telephone, Bluetooth, WiMAX, outdoor broadcasting, Direct Broadcast Satellite (DBS), Personal Communication Systems (PCSs), WLANs, automobile collision avoidance systems. |
| Electronics | Fast jitter-free switches, phase shifters, HF generation, tuning elements, Electronic Counter Measure (ECM/ECCM) systems, spread spectrum systems. |
| Commercial Uses | Burglar alarms, garage door openers, police speed detectors, non-contact identification, cell phones, pagers, satellite television, motion detectors. |
| Navigation | Global Positioning System (GPS) and other global navigation satellite systems. |
| Military and Radar | Target range/speed detection, SONAR, air traffic control, weather forecasting, ship navigation, minesweeping, speed limit enforcement. |
| Research | Atomic and nuclear resonances. |
| Radio Astronomy | Marking cosmic microwave background radiation, detecting powerful waves and radiations in the universe. |
| Food Industry | Microwave ovens, food processing (pre-heating, roasting, drying), moisture leveling. |
| Industrial Uses | Vulcanizing rubber, analytical chemistry, processing ceramics, sterilizing pharmaceuticals, power transmission, tunnel boring, breaking rock/concrete, RF Lighting, fusion reactors, active denial systems. |
| Semiconductor Processing | Reactive ion etching, chemical vapor deposition. |
| Spectroscopy | Electron Paramagnetic Resonance (EPR/ESR) Spectroscopy for studying unpaired electrons and free radicals. |
| Medical Applications | Monitoring heartbeat, lung water detection, tumor detection, regional hyperthermia, angioplasty, microwave tomography, and acoustic imaging. |