Phase Factor in wave propagation (lossy medium): does the distance matters?

AI Thread Summary
In wave propagation through a lossy medium, the phase factor (BETA) represents the phase shift per meter, while the attenuation factor (ALFA) quantifies signal loss over distance. The relationship between distance and phase shift is expressed as BETA multiplied by the distance traveled, indicating that phase shift accumulates with distance. However, unlike attenuation, which is calculated using the formula 8.69*ALFA*d, the phase factor does not have a direct distance-dependent formula for attenuation in dBs. The overall wave propagation can be described using a complex propagator, γ = α + iβ, where α represents attenuation and β represents phase shift. Understanding these relationships is crucial for analyzing signal behavior in lossy media.
Ionito
Messages
14
Reaction score
0
In the electromagnetism theory, the phase factor or constant (usually BETA) in wave propagation for lossy medium has the unit rad/m.

I understood that it must be interpreted as the amount of phase shift that occurs as the wave travels one meter.

However, differently of the attenuation factor (usually ALFA), I cannot see examples relating the phase factor to the distance. In other words, we can see the signal attenuation as the form of 8.69*ALFA*d, where d is the distance between the sender and the receiver. However, this distance "d" is not used in conjunction with the phase factor BETA. Is it right?

Can anyone provide me a complete example of the total attenuation (in dBs), given ALFA, BETA, frequency, and distance d, for a plane wave propagating in a lossy medium?

Thanks
 
Engineering news on Phys.org
Yes, the phase factor appears in the wave equation as beta(phase shift) multiplied with the distance in the direction of wave propagation.i.e if wave is traveling along z direction then phase factor = beta(z)
along with the time dependence wt.

beta is radians per meter,this multiplied with distance gives the phase shift in radians.
 
See the Definitions section of

http://en.wikipedia.org/wiki/Phase_constant#Phase_constant

The propagator in transmission lines is complex; γ = α +iβ. Alpha (α) has dimensions of nepers per meter. Beta (β) has dimensions of radians per meter. The attenuation in dB is 8.686·α·d.

Bob S
 
Hey guys. I have a question related to electricity and alternating current. Say an alien fictional society developed electricity, and settled on a standard like 73V AC current at 46 Hz. How would appliances be designed, and what impact would the lower frequency and voltage have on transformers, wiring, TVs, computers, LEDs, motors, and heating, assuming the laws of physics and technology are the same as on Earth?
While I was rolling out a shielded cable, a though came to my mind - what happens to the current flow in the cable if there came a short between the wire and the shield in both ends of the cable? For simplicity, lets assume a 1-wire copper wire wrapped in an aluminum shield. The wire and the shield has the same cross section area. There are insulating material between them, and in both ends there is a short between them. My first thought, the total resistance of the cable would be reduced...
I used to be an HVAC technician. One time I had a service call in which there was no power to the thermostat. The thermostat did not have power because the fuse in the air handler was blown. The fuse in the air handler was blown because there was a low voltage short. The rubber coating on one of the thermostat wires was chewed off by a rodent. The exposed metal in the thermostat wire was touching the metal cabinet of the air handler. This was a low voltage short. This low voltage...
Back
Top