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By default, power gain is what an RF engineer refers to when s/he talks about "gain." Really they never use that term with antennas without amplifiers? Seems

By default, power gain is what an RF engineer refers to when s/he talks about "gain." Really they never use that term with antennas without amplifiers? Seems like its all over the literature, again back to previous material: 3.1.3 The Power Gain of a Transmitting Antenna The power gain G(θ,ϕ) of a transmitting antenna is defined as the power transmitted per unit solid angle in direction (θ,ϕ) relative to an isotropic antenna, which has the same gain in all directions. Frequently, the value of G is expressed logarithmically in units of decibels (dB): (3.31) For any lossless antenna, energy conservation requires that the gain averaged over all directions be ⟨G⟩=1 (3.32) Consequently, all lossless antennas obey ∫sphereGdΩ=4π. (3.33) Different lossless antennas may radiate with different directional patterns, but they do not alter the total amount of power radiated. Consequently, the gain of a lossless antenna depends only on the angular distribution of radiation from that antenna. In general, an antenna having peak gain G0 must beam most of its power into a solid angle ΔΩ such that ΔΩ≈4π/G0 This motivates the definition of the beam solid angle ΩA ΩA≡4πG0. (3.34) Thus the higher the gain, the smaller the beam solid angle. Directional antenna direct more power to the receiver they do not add more power through amplification. You could also say they waste less power toward no receiver. Reciprocally it works for the receiving antenna as well and is again referred to as gain everywhere I have seen.

CamperBob2 5y ago
Key phrase: "relative to an isotropic antenna." They can call it power gain all they want, but it's still not power gain. The literature is full of imprecise language, and it sounds like that's an example. If an antenna exhibited power gain, you could build a perpetual motion machine with a pair of them. It's not power gain. Instead, it's just less power loss.
- SigmundA 5y ago
  Please point me to precise language that describes antenna gain without using the word gain rather than making a vague declaration. You seem to be trying to pigeon hole the word gain to mean only electronics gain [1] while the word gain has various related meanings [2] and in the RF world antenna gain is precisely defined and does not involve amplification [3]. [1] https://en.wikipedia.org/wiki/Gain_(electronics) https://en.wikipedia.org/wiki/Gain_(electronics) [2] https://www.merriam-webster.com/dictionary/gain https://www.merriam-webster.com/dictionary/gain [3] https://en.wikipedia.org/wiki/Antenna_gain https://en.wikipedia.org/wiki/Antenna_gain
  - CamperBob2 5y ago
    Antenna gain relative to an isotropic radiator is a thing. Absolute power gain from a passive antenna is not. There is no such term as electronics gain. I really don't know how to explain this any more clearly; we're probably talking past each other. In engineering, we don't use the M-W dictionary. Things have to be spelled out more precisely, such as (in this case) exactly what the reference is for a given gain figure. When you see the term 'dB' used in technical writing, it's only a unitless ratio, not a power level, unless explicitly associated with a reference power level. In typical RF discussions, you'll frequently hear 'dBm' or 'dBw' used to describe absolute power levels relative to one milliwatt or one watt, for instance. But the antenna people are more likely to use 'dB' by itself to refer to the gain of one antenna over another, or perhaps 'dBi' to refer to gain over a theoretical isotropic antenna. The latter quantity normally does exceed zero, but only by focusing the existing RF power, not by generating or amplifying it. A related term is ERP, or effective radiated power. Imagine connecting a 1-watt transmitter to the 70-meter dish at a Deep Space Network tracking station. The ERP will be over ten million watts, but it won't even cook your lunch. It's effective power, expressed relative to what you could deliver to a target antenna with an isotropic radiator. Not actual physical power, in the sense of work divided by time.
    - SigmundA 5y ago
      "One key point is that in neither case is any amplification or "gain" present." "Antenna gain relative to an isotropic radiator is a thing." Which is it? Gain clearly does not mean amplification always as I pointed to multiple references and you provided absolutely none. "There is no such term as electronics gain." Again: https://en.wikipedia.org/wiki/Gain_(electronics) https://en.wikipedia.org/wiki/Gain_(electronics) In electronics, gain is a measure of the ability of a two-port circuit (often an amplifier) to increase the power or amplitude of a signal from the input to the output port What game are you playing here, are you really just redefining the english language to win an internet argument?
      - entropicgravity 5y ago
        At the transmitter there are two kinds of gain. The first is simply crack up the power and more signal energy will be received at the receiver. The other "gain" is where the physical shape of the transmitting antenna directs more of the energy it receives in one direction (usually straight ahead) rather than a different directions. The amount of gain due to the physical shape will vary with the frequency of radio wave relative to the physical shape the antenna. Think of a flashlight. The beam is brighter in the middle and falls off towards the sides. That's "gain" compared to a flashlight that beams light in all directions equally, like a sphere. So while the transmitter can "shape the beam" to create gain, the receiver cannot (though the path lose equation implies that it does). The receiver can physically just trap the amount of watts per square metre that it receives and this amount depends only on its size and not on the frequency of the incoming radiation. So the transmitter and receiver antennas are very different in their physics of how the operate but the Path Loss Equations fudges things to make it look like they are the same ie that the gain of either is equally dependent on the frequency/wave length when in fact that's false and the two antennas are asymmetric in how they respond the carrier frequency.

CamperBob2 5y ago

Key phrase: "relative to an isotropic antenna." They can call it power gain all they want, but it's still not power gain. The literature is full of imprecise language, and it sounds like that's an example. If an antenna exhibited power gain, you could build a perpetual motion machine with a pair of them. It's not power gain. Instead, it's just less power loss.

SigmundA 5y ago
Please point me to precise language that describes antenna gain without using the word gain rather than making a vague declaration. You seem to be trying to pigeon hole the word gain to mean only electronics gain [1] while the word gain has various related meanings [2] and in the RF world antenna gain is precisely defined and does not involve amplification [3]. [1] https://en.wikipedia.org/wiki/Gain_(electronics) https://en.wikipedia.org/wiki/Gain_(electronics) [2] https://www.merriam-webster.com/dictionary/gain https://www.merriam-webster.com/dictionary/gain [3] https://en.wikipedia.org/wiki/Antenna_gain https://en.wikipedia.org/wiki/Antenna_gain
- CamperBob2 5y ago
  Antenna gain relative to an isotropic radiator is a thing. Absolute power gain from a passive antenna is not. There is no such term as electronics gain. I really don't know how to explain this any more clearly; we're probably talking past each other. In engineering, we don't use the M-W dictionary. Things have to be spelled out more precisely, such as (in this case) exactly what the reference is for a given gain figure. When you see the term 'dB' used in technical writing, it's only a unitless ratio, not a power level, unless explicitly associated with a reference power level. In typical RF discussions, you'll frequently hear 'dBm' or 'dBw' used to describe absolute power levels relative to one milliwatt or one watt, for instance. But the antenna people are more likely to use 'dB' by itself to refer to the gain of one antenna over another, or perhaps 'dBi' to refer to gain over a theoretical isotropic antenna. The latter quantity normally does exceed zero, but only by focusing the existing RF power, not by generating or amplifying it. A related term is ERP, or effective radiated power. Imagine connecting a 1-watt transmitter to the 70-meter dish at a Deep Space Network tracking station. The ERP will be over ten million watts, but it won't even cook your lunch. It's effective power, expressed relative to what you could deliver to a target antenna with an isotropic radiator. Not actual physical power, in the sense of work divided by time.
  - SigmundA 5y ago
    "One key point is that in neither case is any amplification or "gain" present." "Antenna gain relative to an isotropic radiator is a thing." Which is it? Gain clearly does not mean amplification always as I pointed to multiple references and you provided absolutely none. "There is no such term as electronics gain." Again: https://en.wikipedia.org/wiki/Gain_(electronics) https://en.wikipedia.org/wiki/Gain_(electronics) In electronics, gain is a measure of the ability of a two-port circuit (often an amplifier) to increase the power or amplitude of a signal from the input to the output port What game are you playing here, are you really just redefining the english language to win an internet argument?
    - entropicgravity 5y ago
      At the transmitter there are two kinds of gain. The first is simply crack up the power and more signal energy will be received at the receiver. The other "gain" is where the physical shape of the transmitting antenna directs more of the energy it receives in one direction (usually straight ahead) rather than a different directions. The amount of gain due to the physical shape will vary with the frequency of radio wave relative to the physical shape the antenna. Think of a flashlight. The beam is brighter in the middle and falls off towards the sides. That's "gain" compared to a flashlight that beams light in all directions equally, like a sphere. So while the transmitter can "shape the beam" to create gain, the receiver cannot (though the path lose equation implies that it does). The receiver can physically just trap the amount of watts per square metre that it receives and this amount depends only on its size and not on the frequency of the incoming radiation. So the transmitter and receiver antennas are very different in their physics of how the operate but the Path Loss Equations fudges things to make it look like they are the same ie that the gain of either is equally dependent on the frequency/wave length when in fact that's false and the two antennas are asymmetric in how they respond the carrier frequency.