@m5stack_ag san,
Thank you for your message!
Could you let me know how to set 920MHZ ?

By the way, Specification metal IC Tag of mine is "Up to 4.2M - (US) 902-928MHz, on metal"

Web page shows
"the transmission power of 100mW can reach the effective distance of more than 1.5M."

https://shop.m5stack.com/products/uhf-rfid-unit-jrd-4035?variant=39375750824108

But my JRD-4035 effective distance is 0.4M

If possible , could you let me know why JRD-4035 is low performance ?

Specifications of Output power range is 18-26 dBm

Could you let me know how to adjust max output power 26 dBm?
I found Arduino IDE sample

// UHF_RFID set UHF_RFID设置
RFID.Set_transmission_Power(2600);

Does 2600 mean 26dBm ?

If i set "RFID.Set_transmission_Power(3000) ,Is output power 30 dBm ?

Dear Feimue san

I added "_Noreturn" command on ahead of original sketch as follows
_Noreturn UBYTE UHF_RFID::Set_the_communication_baud_rate(UWORD Pow)

Result : "UHF-RFID-JRD4035" can get data from IC Tag.

--------- Serial monitor ------------

3:02:04.513 -> RSSI :c8
23:02:04.513 -> PC :3000
23:02:04.513 -> EPC :e2806894000040066d70b524
23:02:04.513 -> CRC :7084
23:02:04.513 ->
23:02:04.607 -> RSSI :c7
23:02:04.607 -> PC :3000
23:02:04.607 -> EPC :e2806894000040066d70b524
23:02:04.607 -> CRC :7084
23:02:04.607 ->
23:02:04.700 -> RSSI :ca
23:02:04.700 -> PC :3000
23:02:04.700 -> EPC :e2806894000040066d70b524
23:02:04.700 -> CRC :7084

Dear felmue san,
Thank you for your kindly reply!!
I will try based on your advice from now on !

After compile sample sketch "UHF-RFID-JRD4035", Arduino IDE shows
"no return statement in function returning non-void [-Werror=return-type]" on "RFID_command.cpp"

UBYTE UHF_RFID::Set_the_communication_baud_rate(UWORD Pow)
{

Copy_command_library(13);

ToHex(Pow, 5, 6);

Check_bit_accumulation();
Send_the_modified_command();

} <- this line have error

If possible ,could you help me how to solve this problem ?

I use Atom lite esp32 ,therefore my Arduino IDE setting is as follows
Board :ESP32 Pico Kit
Upload speed :115200

If 10 Metal Tags are placed around the JRD-4035, Can JRD-4035 get the information of MetalTag which is the closest to JRD-4035?
If JRD-4035 can , What parameters does the JRD-4035 need to read ? For example, is it RSSI?

@m5stack san,

Thank you very much for your kindly reply!

Is function of UHF-RFID-JRD-4035 only reading IC tag information ?
Is there function of writing information on IC tag ?
If there is not function of writing information on IC tag , could let me know the writing device that works with Arduino/Atom lite esp32 ?

@felmue san,
Thank you very much for your quickly reply!!
I will continue to investigate it by myself .
If i find additional information, i will describe on this forum.