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Refleksi RFID

Teknologi RFID didasarkan pada prinsip-prinsip ilmiah yang jelas. Tag mengumpulkan energi yang diproyeksikan dari gelombang radio di medan elektromagnetik. Tag kemudian memantulkan kembali sinyal yang diubah menggunakan teknik yang disebut
back-scatter which the antennas receive. Because it is a science, it is often assumed that an expert can accurately predict both the read performance of a tag on any item and the distance it can be read from, just by looking at the system. Unfortunately, reality is much more complex, making RFID operation seem like black magic. In most

Wizard RFID

lingkungan, RFID menghasilkan hasil yang aneh. - Sering kontra intuitif. Biasanya, hasil akhirnya masuk akal setelah diselidiki, tetapi jarang sekali yang pertama kali Anda harapkan.

Terima kasih kepada RR Donnelley & Sons Co. untuk mengirimkan contoh label Custom Wave RFID. Sekarang semua orang tahu tentang pencetakan antena custom RR Donnelley, kan? (Anda tidak? Yah seharusnya. Lihat artikel ini tentang mereka di Jurnal RFID!)

Kami menerima empat tag UHF pasif berbeda yang kami uji di dua lingkungan berbeda.

  1. Di dalam gudang
  2. Di luar di tempat parkir terbuka

Di bawah ini adalah hasil tes jangkauan.

CW-100-04U7CW-100-08MR6
Tatahan04U701MR6
Pengukuran Inlay18 mm * 44 mm22 mm * 60 mm
Kisaran Baca Gudang2.2 meter6.22 meter
Luar Ruang Baca2.13 meter3.35 meter

CW-100-01MR6CW-100-05U7
Tatahan08MR605U7
Pengukuran Inlay95 mm * 8 mm50 mm * 30 mm
Kisaran Baca Gudang6.83 meter9.19 meter
Luar Ruang Baca4.72 meter5.18 meter

Why is there such a significant difference in read range between the two environments if we are using the same reader and the same tags? Most likely the answer is due to reflection of RF energy. The diagram below shows the environment in our warehouse which we tested. The tags were being read down a corridor bordered by pallets of paper products. The image shows how the RF field might be reflected to improve our range.

Diagram Uji Gudang

Artikel grafis Refleksi RFID

The warehouse test diagram illustrates a reader with energy reflected down the corridor. Only a small amount of the energy output from the reader is able to escape through space between the pallets and up into space above the pallets. In this warehouse trial, the tag was able to be read from further away because there was more RF energy available to power the tag than there would have been in the open. Additionally, the large metal door behind the tag could have reflected energy back towards the tag, which would give the tag a double dose of RF energy.

Outside, most of the RF energy that was not oriented directly at the tag was lost because it escaped into space. The RF energy around the tag was weaker and it could not power the tag at the longer distances.

Refleksi tidak hanya mengubah kemampuan Anda untuk membaca tag, tetapi juga menciptakan situasi membaca tag yang aneh. Selama pengujian luar, kami menemukan apa yang kami pikir adalah rentang baca maksimal untuk CW-100-05U7 di 4 meter. Pada meter 4.5, kami tidak dapat membaca tag. Namun, pada meter 5, pembaca menemukan kembali tag itu. Mengapa pembaca dapat membaca dari 5 meter tetapi bukan 4.5 meter? Tentu saja jawabannya adalah refleksi. Gambar di bawah ini menunjukkan fenomena yang kita lihat.

Bidang Energi RF

Bidang Energi RF

Passive UHF tags are dormant until they are powered by enough energy to send a response. In the example above, the RF energy is powerful enough to read a tag anywhere in the first area without any reflection. Then there is a small gap between fields. There is likely energy in the gap between the blue areas, but it is not enough to power the tag. In the small blue areas to the right of the large oval, the RF energy is enhanced via reflected RF waves increasing the energy available to the tags. In this situation, it may have reflected from the ground or nearby vehicles, as shown in the image below.

RF Reflection

RFID Bounce

Apa yang bisa kita ambil dari ini?

Testing is critical as it is almost impossible to consider all factors which you may see in your actual environment. More than focusing solely on the tag and reader, consider the places where the field will be at its weakest and adjust the tag or antenna locations if possible.

Anda dapat melihat video tentang bagaimana ini bekerja dalam praktik di bawah ini. Papan LED yang menunjukkan, menunjukkan kekuatan medan dengan Sensor Telaeris UHF.

RF reflection is one of many aspects of an RFID system to consider. For more information on RFID systems please contact sales@telaeris.com. Untuk informasi lebih lanjut tentang label Custom Wave RFID, periksa situs web mereka di http://www.rrdonnelley.com/printed-electronics/customwave/.

Note: Handheld RFID readers are not usually the best solution for long distance scanning. Fixed readers and antennas will typically provide a longer read range as the readers project more RF energy.

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