RF Attenuators

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Purchased Attenuators[edit]

Programmable Attenuator[edit]

PE4302 P1833-720px.jpg

Triple Attenuator[edit]

ATTEN4 CHINA PCB.PNG

Homebrew RF Attenuators[edit]

Atten 30dB 20dV P1812-720px.jpg

Homebrew RF Attenuators

Attenuator Design - Rev 2[edit]

ATTEN1 P1896-720PX.jpg

  • 6 dB resistor values in above
  • OshPark clear soldermask "After Dark"
    • $4.40 for 6 cards
  • Small/light enough to hang directly off fragile devices
  • SMA connectors
    • Male/female are good choices for direct connect to devices
  • Resistors
    • 1206
      • 1/4W
      • 1% values get good accuracy (approx. 2%) even though not exact to calculated values
  • Good bandwidth up well past RF

10dB Attenuator.PNG

Parts[edit]

Mfr. # Manufacturer Customer # Qty R1/R2 Description
RK73H2BTTE17R8F KOA Speer ATTEN_03DB 1 R1 Resistors - SMD 1/4W 17.8 ohms 1%
RC1206FR-07294RL YAGEO ATTEN_03DB 2 R2 Resistors - SMD 294 ohms 1/4W 1206 1%
RK73H2BTTD37R4F KOA Speer ATTEN_06DB 1 R1 Resistors - SMD 1/4W 37.4 ohms 1%
CRCW1206150RFKEAC Vishay ATTEN_06DB 2 R2 Resistors - SMD 1/4Watt 150 ohms 1%
RC1206FR-0771R5L YAGEO ATTEN_10DB 1 R1 Resistors - SMD 71.5 ohms 1/4W 1206 1%
RC1206FR-0797R6L YAGEO ATTEN_10DB 2 R2 Resistors - SMD 97.6 ohms 1/4W 1206 1%
RK73H2BTTD1070F KOA Speer ATTEN_13DB 1 R1 Resistors - SMD 1/4W 107 ohms 1%
RC1206FR-0778R7L YAGEO ATTEN_13DB 2 R2 Resistors - SMD 78.7 ohms 1/4W 1206 1%
AC1206FR-07249RL YAGEO ATTEN_20DB 1 R1 Resistors - SMD 249 ohms 1/4W 1206 1%
RK73H2BTTDD61R9F KOA Speer ATTEN_20DB 2 R2 Resistors - SMD 61.9 ohms 1%
RK73H2BTTD7870F KOA Speer ATTEN_30DB 1 R1 Resistors - SMD 1/4W 787 ohms 1%
AC1206FR-0753R6L YAGEO ATTEN_30DB 2 R2 Resistors - SMD 53.6 ohms 1/4W 1206 1%
RC1206FR-072K49L YAGEO ATTEN_40DB 1 R1 Resistors - SMD 2.49k ohms 1/4W 1206 1%
RK73H2BTTD51R0F KOA Speer ATTEN_40DB 2 R2 Resistors - SMD 1/4W 51 ohms 1%
RK73H2BTTDD49R9F KOA Speer ATTEN_50_60DB 2 R2 Resistors - SMD 49.9 ohms 1%
RC1206FR-077K87L YAGEO ATTEN_50DB 1 R1 Resistors - SMD 7.87k ohms 1/4W 1206 1%
RC1206FR-0726K1L YAGEO ATTEN_60DB 2 R2 Resistors - SMD 26.1k ohms 1/4W 1206 1%

Measurements[edit]

  • NanoVNA
  • S21 gain
  • 1-900 MHz scan
  • Calibrated with cable on thru

6 dB Attenuator[edit]

  • Flat from 1-600 MHz
  • Higher attenuation past 600 MHz
  • S21

ATTEN1 NanoVNA 6dB S21 1-900MHz.png

  • S11 from 1-900 MHz

ATTEN1 NanoVNA 6dB S11 1-900MHz.png

40 dB Attenuator[edit]

  • Flat from 1-600 MHz
  • Higher attenuation past 600 MHz
  • -39.9 dB at 14 MHz
  • S21

ATTEN1 NanoVNA 40dB.png

  • Flat from 1-30 MHz
  • S21

ATTEN1 NanoVNA 40dB 1-30MHz.png

  • s11
  • 1-900 MHz

ATTEN1 NanoVNA 40dB S11 1-100MHz.png

  • VSWR
  • 1-900 MHz

ATTEN1 NanoVNA 40dB VSWR 1-100MHz.png

DC Block[edit]

  • Use same PCB
    • Install 0.1uF cap between the two SMAs
    • Leave off resistors to ground
  • Sweep 50 KHz to 900 MHz
  • S21 of -0.8 dB at 50 KHz
  • S21 of 0.44 dB at 900 MHz

ATTEN1 NanoVNA DC-BLOCK S21 50KHz-900MHz.png

  • Sweep 50 KHz to 900 MHz
  • S11

ATTEN1 NanoVNA DC-BLOCK S11 50KHz-900MHz.png

Attenuator Charts[edit]

DBm vs milliVolt milliWatts.PNG

DBm vs Volta Watts.PNG

DBm vs Volt Watts.PNG

References[edit]

  • Heavily inspired by Alan (W2AEW) video

W2AEW Attns-01.PNG

W2AEW Attns-02.PNG

W2AEW Attns-03.PNG