​DIY RFID Antenna Kit – 5dBi UHF Build-It-Yourself Design​

The kit works across 840–960 MHz, so you can adjust it for your region. For 865–868 MHz, stretch the spiral traces a bit and trim the PCB, then check the VSWR. For 902–928 MHz, shorten the traces and tweak the screws by the SMA connector, then test the read range. A handy trick—mark each antenna after tuning so you don’t mix them up.

Metal can mess with reads, so start by putting the included neoprene spacer between the antenna and the metal, and use nylon screws to keep parasitic capacitance low. Wrapping the coax with ferrite beads and adding ferrite sheets under the PCB helps cut ground loop noise. If interference still shows up, shift the frequency a bit—like tuning to 890 MHz instead of 915 MHz. In one warehouse with steel racks, these tweaks bumped read rates from 72% to 98%.

You can keep it simple. Place about 50 tags in a 1 m² grid and walk across with your reader at 30 dBm, aiming for at least 90% reads at 4 m. To see the beam, use the free RFID Beam Mapper software and slowly rotate the antenna. You can estimate VSWR with a $25 meter, adjusting the screws until it reads ≤1.5:1. Don’t forget to jot down all results in the logbook for later reference.