Model 1P520
Rev B
Typical Performance: 1.4 GHz. – 2.3 GHz.
Coupling 1P520S
-18
Return Loss 1P520S
0
-10
-20
-30
-40
-50
-19
-20
-21
-22
1.4
1.5
1.6
1.7
1.8
1.9
2
2.1
2.2
2.3
1.4
1.5
1.6
1.7
1.8
1.9
2
2.1
2.2
2.3
Frequency (GHz)
Frequency (GHz)
Directivity 1P520S
Transmission Loss 1P520S
-10
-20
-30
-40
-50
0
-0.1
-0.2
-0.3
-0.4
1.4
1.5
1.6
1.7
1.8
1.9
2
2.1
2.2
2.3
1.4
1.5
1.6
1.7
1.8
1.9
2
2.1
2.2
2.3
Frequency (GHz)
Frequency (GHz)
COUPLING
VSWR & DIRECTIVITY
Choice of a coupling value in an application normally In directional couplers, directivity is specified in lieu of
depends on the power level of the main (sampled) line. isolation. Directivity is a measure of how well the coupled
For example, if the coupler is being used to monitor main power is isolated from reflections at the main line output
line power, the coupling value is selected to provide port. For example, open or short-circuiting the output port
sufficient power to the monitoring device and yet of a coupler with 20dB directivity would only affect the
minimize system loss. Note that any coupler reduces coupled output power by 1% and only 0.1% for 30dB
power flowing in the main line by the amount coupled off; directivity. High directivity is especially important if the
a 10dB coupler reduces main line power by 1 dB (10%) coupler is being used to measure the VSWR of a device
where a 20dB coupler reduces it by only 0.044dB (1%).
at its output port.
In this application, accurate
measurements of forward and reverse power are
Anaren uses mean coupling and frequency sensitivity required.
with the coupling specification. The mean coupling value
is arrived at by periodically sampling the coupling value In theory, VSWR and directivity characteristics of a
over the specified band and averaging the readings. coupler are perfect; the input and output ports are
Frequency sensitivity is the peak to peak variation in perfectly matched and no power is coupled to the isolated
coupling over the specified band.
port. In practice, factors associated with the design and
manufacturing processes limit VSWR and directivity. The
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