Relationship between frequency and distance
Please can anybody explain how the frequency of a communication signal affect its propagation range?
Answer:
In electrical engineering, the relationship between frequency and distance can be analysed in the context of signal propagation through transmission lines or wireless communication systems. Here are a few key points to consider:
Transmission Line Propagation: In the case of transmission lines, such as coaxial cables or twisted-pair cables, the relationship between frequency and distance is affected by the transmission line's characteristics. High-frequency signals tend to exhibit different behaviours compared to low-frequency signals.
Attenuation: As frequency increases, transmission lines tend to have higher attenuation, meaning that the signal power decreases more rapidly over distance. This is due to factors such as resistance, dielectric losses, and skin effect, which become more pronounced at higher frequencies.
Dispersion: Another factor is dispersion, which refers to the distortion or spreading of a signal as it propagates. In some transmission lines, dispersion becomes more significant at higher frequencies, leading to a degradation of signal quality and a limitation on the distance over which the signal can be reliably transmitted.
Impedance Matching: The relationship between frequency and distance also involves impedance matching considerations. Transmission lines are designed to have a characteristic impedance that matches the impedance of the source and load devices. When the frequency changes, the impedance characteristics of the transmission line can affect signal reflections and distortions, which can impact the signal quality over distance.
Wireless Communication: In wireless communication systems, the relationship between frequency and distance can be analysed in terms of propagation characteristics, such as free space path loss and signal fading.
Free Space Path Loss: In general, the signal strength decreases as the distance between the transmitter and receiver increases. The rate at which the signal power decreases with distance is determined by the frequency and is typically described by the free space path loss equation. Higher frequencies, such as those used in microwave or millimeter-wave communication, tend to experience more significant path loss compared to lower frequencies, such as those used in radio or television broadcasting.
Signal Fading: Signal fading refers to the fluctuation in signal strength caused by interference, reflections, and scattering in the wireless propagation environment. The severity of fading can vary with frequency. For example, higher frequencies are more susceptible to multi-path interference, where signals arrive at the receiver through multiple paths with different delays, resulting in constructive or destructive interference. Lower frequencies are less prone to multi-path interference but may be affected by other types of fading phenomena.
It's important to note that the specific relationship between frequency and distance in electrical engineering applications can be influenced by various factors, such as the specific transmission medium, environmental conditions, interference, and system design considerations.
Therefore, detailed analysis and modelling are often required to understand and optimise the performance of systems operating at different frequencies and distances.
Antenna Design and Beamwidth: In wireless communication systems, the frequency of operation affects the design and characteristics of antennas. Higher frequencies generally require smaller antenna sizes, while lower frequencies require larger antennas. The beamwidth of an antenna, which determines the coverage area, is also influenced by frequency. Higher frequencies tend to have narrower beamwidths, resulting in a more focused coverage area and potentially limiting the distance over which the signal can be effectively transmitted.
Multi-path Interference: In wireless communication, multi-path interference occurs when signals take multiple paths to reach the receiver due to reflections, diffraction, or scattering. This interference can cause signal fading and affect the quality of the received signal. The impact of multi-path interference on the received signal strength and quality can vary with frequency. Higher frequencies are more susceptible to multi-path interference, whereas lower frequencies are relatively less affected.
Frequency-dependent Losses: Different transmission media and components used in electrical engineering exhibit frequency-dependent losses. For example, in fiber optic communication systems, signal attenuation can vary with frequency due to absorption and scattering effects. In RF circuits, components such as capacitors and inductors can have frequency-dependent losses, which can affect the performance of the circuit and the distance over which signals can be transmitted reliably.
Regulatory Considerations: The frequency used in communication systems is regulated by government agencies. Different frequency bands have different regulations and licensing requirements. Higher frequency bands, such as those used for cellular networks or satellite communication, often have shorter propagation distances due to their higher path loss characteristics. Lower frequency bands, like those used for AM/FM radio or TV broadcasting, can provide longer propagation distances due to lower path loss. These regulatory considerations play a role in determining the maximum distance and coverage of communication systems.
Interference and Noise: The relationship between frequency and distance is also affected by interference and noise sources. In wireless communication, interference from other devices operating at similar frequencies can limit the distance over which a signal can be reliably received. Moreover, atmospheric noise and environmental factors can introduce additional noise into the received signal, affecting its quality and the distance over which it can be effectively transmitted.
It's worth noting that the relationship between frequency and distance is a complex topic with various considerations in different applications. The points mentioned above provide a broad overview, but specific scenarios and technologies may have additional factors to consider.
Replies
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Abhishek RawalLow frequency(LF) is longer than High Frequency (HF) signals, hence it has less penetration power. So, when it comes to sending information signals to larger distance, LF fails. (Which means LF can carry less information)
While HF has high penetration power, thus it can easily send information to large distance. (Which means HF carries more information)
Also Power plays major role in information transmission. larger the power, larger the distance covered. -
lalI thought it was the other way around. Low frequency signals are of larger wavelength than that of high frequency waves and they travel longer, for the same power.
In the case of visible light, waves of shorter wavelength/high frequency travels less (blue light) and those with larger wavelength/low frequency travels longer (red light) distances.
Isn't it the case with coomunication signals too. Besides those are all electromagnetic waves. -
Abhishek RawalE = hf
Which means Energy is directly proportional to frequency.
Low frequency have low energy, so less distance traveled & thus HF can travel long distance.
Correct me if I am wrong. -
Jeffrey ArulrajE=h*V
h= planck's constant
v= frequency of signal
So higher the frequency longer the distance you can transfer
Most of all this is not a good way to look into communication do tell in What form you are trying to transfer data
Digital or Analog format ? -
Abhishek Rawal
I think, Digital signals cannot be transmitted between two antennas (i.e through air)Jeffrey SamuelDigital or Analog format ? -
Olu_OlaThanks All, but is there a mathematical equation that can approximate the maximum distance a signal will travel in a free space before it becomes too weak to be received by any antenna, given a specific frquency (say 2.4GHz)?.
I use free space bearing in mind that so many factors affect signal quality in our atmosphere. -
Jeffrey ArulrajCan you share the equation or the name of the equation you found?
@#-Link-Snipped-# -
Ahsanul haqueFrequency has nothing to do with distance, the only reason frequency is sometimes associated with distance, is the length of one full RF cycle in the air, this is calculated with the following formula:
speed= distance /time
speed=wavelength*frequency So, wavelength*frequency=distance/time
And, wavelength=distance/(time*frequency)
Frequency and distance are directly proportional the higher the frequency the more distance for the sound to dissipate th lower the frequency th shorter the distance for the sound to dissipate
Thanks -
Darren SimpsonThe communications signal distance travelled is based upon the total link loss available in the system. If the tx is +40dBm and Rx sensitivity is -100dBm then the total link loss available is 140dB. In a free space environment, lower frequencies will travel further over higher frequencies (K+20logd+20logf where K is the Boltzmann constant d is distance and f is frequency).
VHF 120MHz is great for long distance such as ground to air comms at an airport and can talk to planes miles away. UHF 450MHz is still good for distance but not as far and is good for penetration into buildings over VHF due to its smaller wavelength size compared to the size of construction materials. -
AlphinFrequency actually has various characteristics ..for sky wave n ground wave..in general high frequency has lower wave length so it disturbed due to more vibration...but low frequency has greater wavelength so it is not disturbed easily by molecules..so low frequency can travel further..but many asked RF transmission is high frequency..how does it travel further.. actually high frequency can carry more information .when it is transmitted with higher power even high frequency can travel longer....to be clear ..consider same frequency with different power ..the number of vibration will be same only..but the amplitude will increase and the envelope will be big..which makes it easier to travel longer.....
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AlphinAbhishek RawalE = hf
Which means Energy is directly proportional to frequency.
Low frequency have low energy, so less distance traveled & thus HF can travel long distance.
Correct me if I am wrong. -
AlphinIam an electronics n communication engineer..people have misunderstood the concept wrongly...low frequency signals have larger wavelength ..so it's vibration is less so it is easily not disturbed ...it can travel long distance..high frequency has higher vibration n lower wavelength..it cannot travel long...for example consider microwave em wave since it's wavelength is low it can break the bond of water molecule ...if it's wavelength is high it will neglect several molecules n break few bonds ..it is how microwave oven works..so higher the frequency higher the disturbance n lower the propogation..I have undergone internship at air navigation n surveillance..CNS ..UHF transmitters are used for short distance..hf transmitter for long distance....there was an answer stating that E=hf ..I agree energy increases ..but that energy doesn't mean that it can travel longer..it means it can disturb more..that's why microwave frequency produces heat ..but people my wonder how microwave is used in ovens n also in satellite communications...... microwave is high frequency ..so it has many cycles per second...so in sattelite communication data rate can be transferred high...but now comes the doubt..how high frequency can be transmitted so far...now POWER plays an important role...when power is increased voltage is increased the wavelet becomes larger ..but it vibrates in same frequency only..same frequency with different power travel different distance..as power is related to volt or amplitude of the wave..so wavelet becomes larger ...high data rate using mw frequency ..at the same time with high power.....Sry if this answer was too lengthy
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Louis Chung
Total energy =n* hf
If we apply the same power for high and low frequency wave, the number of photon would be inversely proportional to the frequency. Thus more photons will increase the tranvel range im air at lower frequency
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J Lee Hughes
High hz more data
But there is a curve rely low go sHort but ground esh middle bonus of atmosphere and really high frequencies can go out to space
When you get into really high frequencies becomes more line of sight
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