I evaluate a $15 RF Return Loss Bridge I purchased on Ebay and compare its performance against the $85 Directional Coupler I have previously been using for Return Loss tests.
Available on Ebay:
Search phrase "RF Bridge Ukraine"
The video shows results for 0.1-1500 MHz as well as 144 MHz, 222 MHz, 432 MHz, and 1296 MHz Antennas.
I note an error at 3:59. The annotation indicates that performance is 40dB Return Loss with a 50 Ohm load below 150 MHz. This should have been 50 MHz. This unit is still better than 35 dB Return Loss below 150 MHz, however.
Some of the Return Loss error may be due to the quality of the Reference Load that I was using for these tests since its VSWR spec is only 1.2:1 or less at these frequencies. This is a Return Loss of only 21dB or so... not exactly a laboratory grade load.
To search Ebay for these units use:
"RF bridge 1500 MHz" to find the boxed version (various vendors).
"RF Bridge 3000 MHz" to find the board version.
Note: The PCB version is marked "1000 MHz" but the actual working range may be higher if truly high precision Reference and Dummy loads are placed on the REF and DUT ports as seen in the spectrum picture shown on the 64dbmcom site.
19 авг 2024
