- #1
Noudi
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Why antenna needs to be smaller in size with higher frequencies (EM waves)? please
Smaller Antennas, Higher Frequencies: The Need for Size Reductions
- Thread starter Noudi
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In summary: The wavelength of an EM wave is inversely proportional to the distance between the transmitter and the antenna.
- #2
Baluncore
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Because antenna dimension is proportional to wavelength.
Wavelength = speed of light / frequency
Wavelength = speed of light / frequency
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berkeman
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Noudi said:
Welcome to the PF.
This introductory article should also help: http://en.wikipedia.org/wiki/Antenna_(radio )
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Noudi
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Thanks Dear.
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sophiecentaur
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Actually, it's rather the other way round. The antenna for a high frequency (short wavelength) can be small. For low frequency, they need to be big.Noudi said:
When you want to launch an EM wave into space, you need to 'match' your transmitter to the antenna - in order to get the power out into space. The mechanism that causes power to be radiated (which is what the whole thing is about) ls the equivalent to a resistance for the transmitter to drive into. As the antenna gets to be a small fraction of a wavelength, this (radiation) resistance gets lower and lower - the limit being a short circuit. It is very difficult to put much power into an extremely low resistance because all the power gets dissipated in the transmitter and the connecting cable. Hence, to transmit Radio Signals at 198kHz (BBC Radio 4 Long Wave @ Droitwich) the transmitting antenna (the actual wires that radiate - not just the tower height) is a T shape with the vertical section about 100m high. Even with this massive structure, the antenna is not very efficient and a significant amount of power just warms up the metalwork and the ground nearby. For your Mobile phone, which uses wavelengths of much less than 1m, the antenna can be made to fit inside the case quite easily and is a pretty efficient design (for battery like).
To get good directivity, you need antennae that take up several (or even hundred) wavelengths. Hence the massive 'dishes' for radio astronomy.
Related to Smaller Antennas, Higher Frequencies: The Need for Size Reductions
1. What is the significance of reducing antenna size?
Reducing antenna size is important for a variety of reasons. First, it allows for more compact and lightweight communication devices, making them more portable and easier to integrate into different systems. Second, smaller antennas can operate at higher frequencies, which allows for increased data transmission rates and better signal quality. Finally, smaller antennas can be less expensive to manufacture, making them more cost-effective for mass production.
2. How does increasing frequency affect antenna size?
The size of an antenna is directly proportional to the frequency it operates at. This means that as frequency increases, the antenna size decreases. This is because higher frequencies have shorter wavelengths, which require smaller antennas to effectively transmit and receive signals. Therefore, in order to operate at higher frequencies, size reductions are necessary for antennas.
3. What challenges are faced when reducing antenna size?
Reducing antenna size poses several challenges for engineers and scientists. One of the main challenges is maintaining antenna efficiency and performance while decreasing its size. This can be achieved through careful design and optimization techniques. Another challenge is ensuring that the antenna can withstand environmental factors and maintain its functionality. This requires robust materials and designs to prevent damage or interference.
4. What are some techniques used for size reduction in antennas?
There are several techniques used for reducing antenna size. One common method is the use of metamaterials, which are artificially engineered materials with unique electromagnetic properties that can be used to miniaturize antennas. Another technique is the use of fractal geometries, which allow for more compact and efficient antenna designs. Additionally, new technologies such as 3D printing are being explored for creating smaller and more complex antenna structures.
5. How does size reduction impact the performance of an antenna?
While size reduction is necessary for operating at higher frequencies, it can also have an impact on the performance of an antenna. Smaller antennas may have reduced efficiency and coverage compared to larger antennas. Additionally, reducing the size of an antenna may limit its bandwidth and frequency range. Therefore, careful design and testing are crucial to ensure that the performance of the antenna is not significantly affected by the size reduction.
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