The antenna coupling system can be represented by a four terminal network. In the case ofĪntenna, however, the coupling is weak and the field involved is In the case of transformer, theĬoupling is strong and the field involved is entirely magnetic. Radio communication system the receiving antenna is linked to the transmittingĪntenna through the electromagnetic wave. This is the entire process of modulation and demodulation what happens in our radio, TV, modems etc. This is known as demodulation and baseband signals are extracted and reconstructed. Here carrier signals are received and they go for a reverse modulation process. Receiver is the other end of the signal transmission. Radio signals are then feed to transmitter. Some signal properties like amplitude, frequency or phase are changed as per baseband signals. Radio signal used as carrier for the baseband signals. This property of radio signal is utilised in signals transmissions. However radio frequency signals have the property to propagate longer distances in space. They are called baseband signals and can not propagate in space. These electronic signals are low frequency signals. Repeaters will amplify the signals and boot the signal strength. Repeaters are required to transmit these for longer distances. Signals attenuate as the distance increases. are such examples.Ĭopper wire for audio signals and co-axial cable for video signals are good for transmission of these signals upto few kilo meters. They can be transmitted via copper wire for few kilometers.
![antenna and wave propagation haykin antenna and wave propagation haykin](http://image.slidesharecdn.com/antennaswaveandpropagation-140726081438-phpapp01/95/antennas-wave-and-propagation-5-638.jpg)
These signals can have a frequency range of audio signals 20hz-20kHz or Video signals of bandwidth of few Mhz. Mainly these are very low frequency signals or DC signals having no frequency or phases.Įlectronic signals however are different and they mainly have low amplitude (below 15V) and they mainly used for audio, video, or on-off signals and digital signals used in computers. Alternating voltage can range up to a frequency of 50-60Hz. They are either high voltage or high current signals. They are mainly used to deliver power to the device. Electrical signals are mainly power carrying signals like AC or DC power lines. Signals are broadly divided into two categories and they are electrical signals and electronic signals. Electronics circuits deals with many types of signals.