Why dont we prefer low frequency signals for signal transmission

Replies

• 

  Ali.imran

  it depends on what you are trying to transmit. In case of transmission line, impedance is considered zero according to circuit theory at low frequency but the same transmission line can have high impedance at high frequency.
  
  Z= R+jwL ;w=2*pi*f
  As frequency increases impedance increases so low frequency is preferred.
  on the other hand FM radio, TV broadcast and even air navigation system use Very High frequencies.
• 

  Nithyasri

  Ya i hav got some idea.....TanQ u so much!!!!
• 

  Nithyasri

  But still i could not get the exact idea?is this anything connected to antenna parameters?
  can u make me much more clear??
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  Ali.imran

  i don't think antenna parameter should be a problem because antenna are selected according to the transmitting frequency. Frequencies are not selected according to antenna parameters.
  extremely low frequencies are used for submarine communication system and they have their own antenna.
  RC planes operate at 45Mhz apprx. and they have their own antennas
  gsm use 900/1800 Mhz antenna (cell phone antennas)
  what i am trying to say is that you select a transmitting frequency and use antenna according to it.
  I can't help you further because my engineering discipline is electrical and i only know the basic about communication and antenna. perhaps the following link will make thing clear:
  The Antenna Theory Website
• 

  sudha madhuri

  We know that wavelength is inversely proportional to frequency. The antanna length is calculated interms of wavelength and it's value must be atleast wavelength /10.So for a small frequency wavelength is more and hence the antenna length will also become large. For a high frequency the wavelength is small and hence the length of antenna will also be small. Especially in this case high frequency signals are preffered for transmission. Thats why we are using a small antenna in our mobile phones whose operating frequency is in the range of 800MHz.
• 

  hsirah5

  Nithyasri

  Why dont we prefer low frequency signals for signal transmission?

  
  Nithyasri,
  For a successful transmission of information, we need to ensure that there is no data loss during the transmission. Signal with higher energy suffers lesser loss of information. The energy of a signal is propotional to its frequency
  (Mathematically Energy of signal= Planck's constant * frequency). Hence greater the frequency of a signal, higher its energy.
  
  Thats the reason why high frequncy signals are used. Even in modulation, the information is wrapped with a high frequency carrier signal and transmitted. The high frequency carrier wave (with high energy) is received and demodulated to get the original signal.
  
  Hope this gives you a better understanding.😎 Please let me know if you need further clarification.👍
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  mohdp

  power directly prpsional to frqncy,so low freqncy waves can be transmitt low power
  i think we can use low freqency wave use in toys and small area communication