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What is S11 of antenna?
S11 (return loss) represents how much power is reflected from the antenna, and hence is known as the reflection coefficient (sometimes written as gamma: or return loss. If S11=0 dB, then all the power is reflected from the antenna and nothing is radiated.
What is the difference between S12 and S21?
S-parameters describe the input-output relationship between ports (or terminals) in an electrical system. For instance, if we have 2 ports (intelligently called Port 1 and Port 2), then S12 represents the power transferred from Port 2 to Port 1. S21 represents the power transferred from Port 1 to Port 2.
How do you measure antenna gain using a network analyzer?
Antenna gain characteristic is easily measured using spectrum analyzer with tracking generator….The measurement procedure is as follows:
- Place the two antennas to be tested with a certain distance in the anechoic box.
- Set the center frequency and span of the spectrum analyzer to a band to be observed.
How is antenna gain measured?
* Antenna gain is measured in decibels as either dBi or dBd. dBi refers to dB away from a theoretical isotropic antenna (0), while dBd refers to dB away from a more real world reference dipole antenna with a gain of 2.15 dB. A theoretical perfectly spherical coverage pattern measured in dBd would be -2.15 dBd.
How is antenna VSWR measured?
The voltage standing wave ratio (VSWR) is one convenient metric that is linked to impedance matching within the desired antenna bandwidth. One useful way to evaluate antenna impedance matching is to measure VSWR using a directional coupler.
How is the power received at Antenna 2 measured?
In the above Figure, S21 represents the power received at antenna 2 relative to the power input to antenna 1. For instance, S21=0 dB implies that all the power delivered to antenna 1 ends up at the terminals of antenna 2. If S21=-10 dB, then if 1 Watt (or 0 dB) is delivered to antenna 1, then -10 dB (0.1 Watts) of power is received at antenna 2.
What does S21 stand for in a network?
S21 represents the power transferred from Port 1 to Port 2. In general, SNM represents the power transferred from Port M to Port N in a multi-port network. A port can be loosely defined as any place where we can deliver voltage and current.
What is the gain of the S21 parameter?
If an amplifier exists in the circuitry, then S21 can show gain (i.e. S21 > 0 dB). This means that for 1 W of power delivered to Port 1, more than 1 W of power is received at Port 2.
Which is the best value for antenna S11?
The above would typically be measured using a Vector Network Analyzer (VNA), which can plot S11. The above figure implies that the antenna radiates best at 2.5 GHz, where S11=-10 dB. Further, at 1.5 GHz the antenna will radiate virtually nothing, as S11 is close to 0 dB (so all the power is reflected).