# Week 1 Note (mmWave)
## Name : Christofel Rio Goenawan
## University : Bandung Institute of Technology (ITB)
## Date : 7/1/2020 - 14/1/2020
## Objectives:
1. Understand concept and work of mmWave (What? How? Why ? )
2. Know application of mmWave and the advantage.
## 1. What is mmWave
Millimeter waves ( usually called mmWave ) are electromagnetic (radio) waves typically defined within the frequency range of 30–300 GHz. The microwave band is just below the millimeter-wave band and is typically defined to cover the 3–30-GHz range. The terahertz band is just above the millimeter-wave band and is typically defined to cover the 300 GHz to 3 + THz range. The wavelength of electromagnetic radiation is given by λ= c/f, where c = 3 × 108 m /s is the speed of light and f is the frequency (in Hz). The millimeter-wave band thus corresponds to a wavelength range of 10 mm at 30 GHz decreasing to 1 mm at 300 GHz. The range of mmWave can be seen below.
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This wave can be used for high-speed wireless communications as seen with the latest 802.11ad Wi-Fi standard (operating at 60 GHz). It is being considered by standards organization, the Federal Communications Commission and researchers "as the way to bring 5G into the future" by allocating more bandwidth to deliver faster, higher-quality video, and multimedia content and services.

## 2. How does mmWave work
Just like another range of wave, mmWave used as signal in wireless connection ( by coding the data into PWM of signal ) and as detector of object by using reflection caused by the object. In object detector the transmitting signal can take form of different types of waveforms, including Pulsed, Frequency-Shift Keying (FSK), Continuous Wave (CW), and Frequency Modulated Continuous Waveform (FMCW). TI mmWave Sensors implement Fast FMCW for its robust operation, rapid sensing and reduced ambiguity in dense scenes. Fast FMCW is also able to provide accurate measurement in both range and velocity of objects enabling TI mmWave Sensors to provide multi-dimensional sensing.
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## 3. Why mmWave needed
The needed of mmWave arise because start of 4.0 industry revolution in the world. Because of needed of connection, faster wireless communication needed to provide the connection. One of the way to make connection faster is by using shorter length of wave as signal because the shorter the wave then enable large numbers of antenna elements to be deployed in the same form factor thereby providing high spatial processing gains. This make mmWave suite better for high speed wireless connection.
The other reason mmWave needed is because human need detector that can through some solid object like plastic , clothing etc for security , military , etc. This is provided by mmWave sensor because due to shorter wavelength mmWave can penetrate certain materials such plastic , drywall , and is impervious to environmental conditions such as rain, fog, dust and snow.These reflected wavefronts can be focused by an imaging system that will reveal the size, shape, and orientation of the concealed object.Additionally, operating in this spectrum makes mmWave sensors interesting for the following reasons

1. Ability to penetrate materials: see through plastic, drywall and clothing
2. Highly Directional: compact beam forming with 1° angular accuracy
3. Light-like: can be focused and steered using standard optical techniques
4. Large absolute bandwidths: distinguish two nearby objects
Antenna-on-package integration enables smaller system size

## 4. Application of mmWave
### a. Object Detector
Millimeter waves are effective for explosive detection on personnel because the waves readily pass through common clothing materials and reflect from the body and any concealed items. Due to the technology’s use of small wavelengths it can provide sub-mm range accuracy and is able to penetrate certain materials such as plastic, drywall, clothing, and is impervious to environmental conditions such as rain, fog, dust and snow.These reflected wavefronts can be focused by an imaging system that will reveal the size, shape, and orientation of the concealed object. Diffraction generally limits resolution to spot sizes of λ/2 or larger, so resolution spot sizes of <10 mm are readily achievable at millimeter wavelengths.
### b. High- Speed Wireless Communication
In general, the overall loss of mmWave systems is significantly larger than that of microwave systems for a point-to-point link. However the small wavelengths of mmWave frequencies enable large numbers of antenna elements to be deployed in the same form factor thereby providing high spatial processing gains that can theoretically compensate for at least the isotropic path loss. This advantage make mmWave very suitable for wireless communication in 5G.
The high loss of energy in mmWave signal systemcs can be reduced by limiting the amount of interference between adjacent cells. In addition, where longer paths are desired, the extremely short wavelengths of mm wave signals make it feasible for very small antennas to concentrate signals into highly focused beams with enough gain to overcome propagation losses. The short wavelengths of mm wave signals also make it possible to build multi-element, dynamic beamforming antennas that will be small enough to fit into handsets.