View source for 0/10/20/30 dB Attenuator

[[file:ATTEN4_CHINA_PCB.PNG]]

== Specs ==

DC-4.0GHz 200mW DC 4.0GHz RF Fixed Attenuator SMA Double Female Head 0dB 10dB 20dB 30dB


* From the [https://www.aliexpress.com/item/4000333427604.html?spm=a2g0s.9042311.0.0.52b34c4d4UyEIF AliExpress listing]
** $5 with shipping (2021-10)
* Frequency range: DC - 4.0GHz
* Maximum power: 23dBm (200mW)
* Standing wave ratio: ≤ 1.20
* System impedance: 50Ω
* RF interface: SMA double female head (Outer screw inner hole)
* Attenuation:
** Direct: 0dB (reference)
** Level 1: 10 ± 0.8 dB
** Level 2: 20 ± 1.1 dB
** Level 3: 30 ± 1.5dB

== Measurements ==

* Characterized filters uinf NanoVNA
** 1 to 900 MHz (card spec is up to 4 GHz)
** Through-calibrated with SMA barrel and same cables was flat

=== 0 dB ===

[[file:ATTEN_0DB_1MHz_TO_900MHz.png]]

=== 10 dB ===

[[file:ATTEN_10DB_1MHz_TO_900MHz.png]]

=== 20 dB ===

[[file:ATTEN_20DB_1MHz_TO_900MHz.png]]

=== 30 dB ===

[[file:ATTEN_30DB_1MHz_TO_900MHz.png]]

== Calibrating NanoVNA through the card ==

* Calibrate on card 0 dB (pass-through connections)

=== 0 dB ===

[[file:ATTEN_0DB_1MHz_TO_900MHz_Cal.png]]

=== 10 dB ===

[[file:ATTEN_10DB_1MHz_TO_900MHz_CalOnBoard.png]]

=== 20 dB ===

[[file:ATTEN_20DB_1MHz_TO_900MHz_CalOnBoard.png]]

=== 30 dB ===

[[file:ATTEN_30DB_1MHz_TO_900MHz_CalOnBoard.png]]

== Analysis of Results ==

* Board uses 5% (3-digits) resistors
** Can result be 1dB with 5% resistors?
* Tracks are wide but 50 Ohms?
* 0805 resistors limit power handling to 200 mW max
* Lots of ground stitching
* Compared to Homebrew attenuator
** Homebrew is more accurate in DC-100 MHz range
** Leads may act as inductors/capacitors

[[file:ATTEN_30DB(HOMEBREWvsPURCHASED)_1MHz_TO_900MHz.png]]

== Improvements in design ==