As the first slide states, this presentation has everything you need to know about millimeter waves. What is mmwave? Why the name mmwave? Origin of mmwave? What are the advantages of mmwaves? What are the disadvantages of mmwaves? Why mmwaves are used in the next generation of wireless technology 5G? If will find answers to all these questions in this presentation.

1. Everything you need to know
about “mmwaves”
Todays wireless networks have run into a problem: More people and
devices are consuming increased amount of data like never before, but it
remains crammed on the same bands of RF spectrum that the mobile
networks have always used. This means less bandwidth is available for the
users, causing slower data service or dropped connections.
One way to get around this problem is to consider transmitting signals on
a whole new swath of spectrum, one that’s never been used for mobile
service before. When we start looking for large chunks of unused
bandwidth, mmwaves (millimeter waves) come into the picture.
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By – Pavithra Nagaraj, 5G Researcher

2. What is mmWave Spectrum?
• The mmWave Spectrum corresponds to band of frequencies between
30GHz to 300GHz, and sometimes it is also known as Extremely High
Frequency(EHF).
• Wedged between the super high frequency band and the far infrared
band, it is the subset of microwave radio frequencies.
• The high frequency of millimeter waves as well as their propagation
characteristics make them useful for variety of applications which
includes transmitting large amounts of data. Thus, this spectrum is
currently used for high speed wireless communications as seen in IEEE
802.11ad Wi-Gig Standard (operating at 60GHz).
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4. • This section of spectrum is pretty much unused, so large chunks of
bandwidth is available in this frequency band compared to lower
frequency bands which are currently in use by mobile networks.
• So far, only operators of radar systems and satellites use mmwaves for
real world applications. The use of these frequencies to connect mobile
users to nearby base stations is an entirely new approach.
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5. Why the name ‘mmWaves’?
• As we all know, wavelength(𝜆) can be calculated using the frequency (f)
and speed of light in vacuum (c).
𝜆 =
𝑐
𝑓
When,
f=30GHz, Wavelength will be approximately 10mm since the speed of light is 3.8 × 108
m/sec.
f=300GHz, Wavelength will be approximately 1mm since the speed of light is 3.8 × 108
m/sec.
• As shown above, high frequencies mean narrow wavelengths. The
wavelength of mmwaves range between 1 millimeter to 10 millimetres
whereas the wavelengths of radio waves currently used are mostly
several dozen centimeters in length. Hence the name ‘millimetre Waves’.
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6. Origin of mmwaves ( usage in communication systems)
• Millimetre wave frequencies were first investigated by Indian Physicist
“Jagadish Chandra Bose” during 1894-1896, when he reached upto 60GHz
(approximately 5mm wavelength) in his experiments.
• First demonstrated at the Presidency college, Calcutta, India by transmitting
and receiving electromagnetic waves at 60 GHz, over a distance of 23 meters,
through intervening walls by ringing a bell and detonating gunpowder.
• For this communication system, Bose pioneered in development of entire
mmwave components like Spark transmitter, coherer, dielectric lens, polarizer,
horn antenna and cylindrical diffraction grating.
• It was the first mmwave based communication system in the world, developed
125 years ago. This is also an oldest milestone achievement from the Asian
Continent.
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7. Advantages of mmwaves
• Large Bandwidth
- The large bandwidth available in mmwaves translate to better data
transfer rates, attaining speeds of about 10Gbps or more compared to the 1Gbit/s
limit when using the microwave frequencies. This makes high-quality video
streaming, real-time gaming, and other bandwidth intensive applications a reality.
• Higher resolution
- The narrow beam width allows the ability of mmwaves to achieve greater
resolutions. For Same antenna size, when frequency increases, the beam width
decreases.
• Low interference (High immunity to cramming)
- The narrow beam width and short range can be a benefit since there is less
interference from nearby radios.
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8. • Small components sizes
- The components and antennas for the higher millimeter waves are
usually very small compared to those for lower frequencies. This makes it
possible to design physically smaller circuitry and equipment. Higher the
frequency, Smaller is the antenna size (Large no. of antennas can be packed
in small area).
• Increased security
- In addition, it is much harder to intercept the signals and there is
also increased security since the signal is only restricted to a small area.
• Cost efficiency
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9. Disadvantages of mmwaves
• High manufacturing costs
- Manufacturing the small components require high precision and care, hence
increased costs.
• Limited range.
- Due to the short wavelength, mmwaves have a short transmission range of
about 10 meters for most low power applications. However, the range is extended by
using high transmit power and antenna gains, and receivers with high sensitivity.
• Requires Line of Sight (LOS)
- Physical objects such as trees, buildings, even humans will block the waves,
leading to weak wave signals and a reduced range.
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10. • Vulnerability to atmosphere and meteorological conditions
- The short wavelengths between 1 to 10mm suffer high atmospheric
attenuation; with fog, rain and moisture attenuating the waves the highest, and
shortening the transmission distances. All these factors reduce the possible range
to about one kilometre. Use of high-gain antenna arrays can boost the effective
radiated power and increase the transmission range.
• Over sensitivity of mmwaves can be a problem at certain instances, leading to
false alarm even when there was no real threat.
• In some instances, the mmwaves receiving system may be less sensitive due to
less energy collected by smaller size antennas.
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