Alpha432
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What is gain? If I have more gain in an antenna does that mean it will pick up signal better from things farther away? is 2.5 a good gain for a portable 800mhz antenna?
What is Gain?
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RevGary
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If you have a moment to spend reading, this link gives a basic explaination and is quite accurate...
http://www.marcspages.co.uk/tech/antgain.htm
http://www.marcspages.co.uk/tech/antgain.htm
JnglMassiv
Member
In a word, gain is a multiplier. A gain of 2.5 (no units) will be an increase of signal of 2.5 times the orignal.
Gain is often expressed in decibels (dB). Decibel notation is a way of conveying ratios. Generally, for power ratios (which is usually what we're referring to in communications), the multiplier is calculated by 10^(dB/10). For example, an amplifier gain of 2.5 dB would be 10^(2.5/10) = 10^.25 = ~1.77.
Antenna gain gets tricky. Recall that dB gain is a ratio. The problem is the reference signal. Say you have a 'high gain' antenna but what do you compare its performance to? A common method is to compare against an isotropic antenna. An isotropic antenna is a model that assumes power is effectively transmitted (or, due to reciprocity, received) equally in all directions. They're in the drawer next to the frictionless pulley and ideal capacitor
.This ratio is expressed as Dbi. Note, however, that this is only one way of expressing antenna gain.
Gain is often expressed in decibels (dB). Decibel notation is a way of conveying ratios. Generally, for power ratios (which is usually what we're referring to in communications), the multiplier is calculated by 10^(dB/10). For example, an amplifier gain of 2.5 dB would be 10^(2.5/10) = 10^.25 = ~1.77.
Antenna gain gets tricky. Recall that dB gain is a ratio. The problem is the reference signal. Say you have a 'high gain' antenna but what do you compare its performance to? A common method is to compare against an isotropic antenna. An isotropic antenna is a model that assumes power is effectively transmitted (or, due to reciprocity, received) equally in all directions. They're in the drawer next to the frictionless pulley and ideal capacitor
.This ratio is expressed as Dbi. Note, however, that this is only one way of expressing antenna gain.
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Alpha432
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Ok, thanks!
Gain is when you get paid. Loss is when you pay the bills. Is that simple enough? (;->)
N
N_Jay
Guest
kb2vxa said:
I wish money was in dB!
Sir, I would like a little raise. Just a small one, only 3 dB! :lol: :lol:
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