Quickie
Colonel
Short answer is the 3 waves can have different angles of incidence and still be in phase, and vice versa.
Ask anything Thread (Air Force)
- Thread starter Jeff Head
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from what you say i understand that are some conditions when this may happen or may not what are those conditions and can be applied this to a radar for receive the waves that are reflect from the air into a aircraft (because this can see f22 if works by waves being reflected from back of f22 to front where the radar is )?
I suppose if you have an array of receivers you may be able to differentiate waves from different direction even if they are in phase because they will be arriving at different elements on the array at different times. So with some clever signal processing you may be able to deconstruct the combination of received signals into the original directions. This will also need to take into account of the slightly different electrical length from each receiving element, which will need to be calibrated first. I imaging it is very complex stuff, and needs to be very precise considering the speed of EM wave involved. That's why radar systems are very expensive.
i thinked to that too but is a problem how you differentiate the arrival of those waves by those of noise in the air because we speak about a passive radar where the doppler effect is not taked into account , ofcourse you can see that the waves reflected by a aircraft are different from the noise around but how is the question maybe is another specific mark of the reflected waves in terms of strenght of signal or something
I guess for a white noise you could remove it by some sort of integrating technique. As for interference noise you could try correlating with your pulse to see if they are due to reflections from what you send out or uncorrelated. i.e. if you send a pulse every 50ms you would expect the various returns to be of quite close periodicity.
Modern radars can operated in different bands of frequency and switch between them. You could see if the reflections from different frequencies as you switch through them is consistent. I think that is how modern radars are harder to fool with jammers because they switch transmitting frequency in a rapid and pseudo-random way that make it hard for jammers to sync.
Modern radars can operated in different bands of frequency and switch between them. You could see if the reflections from different frequencies as you switch through them is consistent. I think that is how modern radars are harder to fool with jammers because they switch transmitting frequency in a rapid and pseudo-random way that make it hard for jammers to sync.
check this out it is possible
Reciprocity[]
It is a fundamental property of antennas that the electrical characteristics of an antenna described in the next section, such as , , , , and , are the same whether the antenna is or . For example, the "receiving pattern" (sensitivity as a function of direction) of an antenna when used for reception is identical to the of the antenna when it is driven and functions as a radiator. This is a consequence of the of electromagnetics. Therefore, in discussions of antenna properties no distinction is usually made between receiving and transmitting terminology, and the antenna can be viewed as either transmitting or receiving, whichever is more convenient.
Reciprocity[]
It is a fundamental property of antennas that the electrical characteristics of an antenna described in the next section, such as , , , , and , are the same whether the antenna is or . For example, the "receiving pattern" (sensitivity as a function of direction) of an antenna when used for reception is identical to the of the antenna when it is driven and functions as a radiator. This is a consequence of the of electromagnetics. Therefore, in discussions of antenna properties no distinction is usually made between receiving and transmitting terminology, and the antenna can be viewed as either transmitting or receiving, whichever is more convenient.
Yes, all that means is that if you have antenna A of some type as transmitter and antenna B of some type as receiver with environment C between them, you would get the same results at A when you transmit from B as when you transmit from B and receive at A, provided that A,B, and C remains unchanged.
that show this : when you modulate your signal by phase shift to obtain angles of waves the opposite is corect too aka waves that comes into angles create a phase shift into your circuits which is exacly what i searched for
Similarly when an RF antenna receives a signal the magnetic changes cause a current flow, and the electric field changes cause the voltage changes on the antenna.
also here
Similarly when an RF antenna receives a signal the magnetic changes cause a current flow, and the electric field changes cause the voltage changes on the antenna.
also here
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Hey all,
just got a general question, I was watching the news and saw China's Presidents Xi's plane land in the US yesterday. Did his 747 have fighter escorts when it flew from China to the US?
Air Force One always has escorts, so I'm guessing China's equivalent to AirForceOne would have something similar. Curious as to what escort fighters they had, and would the fighters be allowed in US airspace after crossing the Pacific?
just got a general question, I was watching the news and saw China's Presidents Xi's plane land in the US yesterday. Did his 747 have fighter escorts when it flew from China to the US?
Air Force One always has escorts, so I'm guessing China's equivalent to AirForceOne would have something similar. Curious as to what escort fighters they had, and would the fighters be allowed in US airspace after crossing the Pacific?