r/RFID

Hello Im currently working on a uni project and i kind of need some help,

Im currently working on a small passive NFC prototype using a NXP NHS3152. The goal of the project is to keep the PCB as small and discreet as possible and only bieng powered only from a phone NFC field with the MCU taking a couple of low-power analog readings and sending a simple result back to the phone.

I would like some help with the power side before I go too far with the antenna and PCB layout.

The system would ideally run around 1.8 to 2.0 V when powered by the phone. The sensing load is expected to be fairly low, roughly in the range of a few µA up to maybe 60 to 70 µA depending on the resistor values used.

Rough power estimate would be at 1.8V, 5 µA = about 9 µW, 20 µA = about 36 µW, 65 µA = about 117 µW

and for 2V its would be, 5 µA = about 10 µW, 20 µA = about 40 µW, 65 µA = about 130 µW

I would only power the analog measurement section for less than a second so the average current should be lower than the active measurement current.

Main questions:

1. Is this kind of power budget realistic for a passive NFC tag powered by a smartphone?
2. For the NXP NHS3152, what is the best practical NFC antenna approach on a small custom PCB or if anyone has a NFC design for these specifications?

I’m not trying to transfer much data, just wake from the phone field, take simple readings, and send a small result back to the phone.

Any advice from people who have worked with passive NFC sensor tags, NHS3152/NTAG-style parts, or small NFC antennas would be appreciated!!!

Edit: Forgot to mention the Maximum Size of the Antenna is around 5.8cm × 5.8cm and its going to be printed on a flexible substrate.

Running a brass and bronze idol retail shop in Kumbakonam, Tamil Nadu, India. About 1500 sq ft, currently 286 RFID-tagged items with plans to scale to 2500+. Goal is a reliable daily morning stock count.

Current setup:

Reader: Chafon H102 BLE handheld (26dBm, linear antenna)

Tags: TagMatiks Kickstart 45×19mm poly labels hanging on string cards attached to each idol

Frequency: 865-868 MHz (India/ETSI)

Software: Custom web app via Web Bluetooth + Supabase backend

The problem:

Consistently missing ~55 items per single pass. Tested both our custom app AND the native Chafon app — both get ~232/286 per pass. So it's confirmed not a software issue. Both apps perform identically.

Items are on granite shelves, densely packed. Customers constantly pick up and replace items, changing tag orientation randomly. Tags hang freely on string but naturally fall between items or rotate to face the wall or another idol.

What we've already ruled out:

Software/parsing issues — both apps identical performance

RSSI filtering — tested with threshold at -100 (no filter)

Q Value — tested at Q=9 (optimal for 286 tags)

Session — using S1

What we think the root cause is:

Linear antenna on H102 — tags that rotate to wrong orientation don't get read reliably. Also 26dBm may be borderline for tags that are slightly obstructed by adjacent brass/bronze items.

Considering upgrading to Chainway R6:

Impinj E710 chip

30dBm output

Circular polarized antenna (4dBi)

865-868 MHz confirmed

900+ tags/sec

Price in India: ~₹42,500 (~$425 USD)

My questions:

Will circular polarized antenna on R6 actually solve the tag orientation problem in a dense retail shelf environment like mine?

Is the jump from 26dBm to 30dBm meaningful enough to reduce misses on slightly obstructed tags?

Any real-world experience with R6 in similar retail/showroom environments?

Currently using soft poly labels. Would switching to rigid PVC jewellery-style hard tags (like Alien H3 or Monza chip) improve read consistency? Or is it purely a reader antenna problem?

Any better alternatives to R6 under ₹45,000 (~$450 USD) available in India?

Happy to answer any questions. Building a native Android app using Chainway SDK once hardware is sorted.

Hi everyone,

Just curious if anyone knows what website/device is legitimate to find a microchip on humans? Something that can detect something within a couple of inches away at most. Price range doesnt matter, thanks!

My landlord charges an insane amount to replace the rfdi pool pass thing. I found the exact one on amazon, if I buy it and tell them it doesn’t work would they know that it wasn’t the original?

I live in a building that gives us RFID stickers for our car windshields to open up the parking gate. I have it on my windshield but the sticker is bright white and it bugs me how noticeable it is from the front of the car. Is there any kind of black or dark colored sticker that anyone has put in between an RFID sticker and their windshield to hide the bright color? I assume any type of sticky sheet that I could cut out in the same shape as the tag would work but I can’t find what I’m picturing online.

So I got a chameleon ultra off of AliExpress (most likely a knock off) and I was looking into what the buttons can be set to and found the battery level one. Sometimes when I use said feature, it will flash all LEDs red a few times then display the battery level.

Does anyone know what this means? I tried Google, but couldn't find anything.

Estou fazendo uo das etiquetas RFID na minhas duas loja de confecção própria de roupa, mas tem me gerado mais dor de cabeça que prazer em continuar: primeiro, que até agora não entendi, se a pessoa cortar ao meio ela deixa de funcionar mesmo? e por ultimo, tem clientes que estão sendo barrados na porta, pois o alarme dispara, mesmo desativando.

amigos empresários, afirmaram que se embrulhar com papel aluminío o alarme deixa de tocar...enfim, mais dúvidas que certeza.