How Can I Make a RFID Reader Read Backwards? Complete Guide to Reverse Reading

I got an interesting question from a customer last week: how can I make a RFID reader read backwards? They were setting up a warehouse system and needed to read tags behind shelving without walking around every time. It’s not as crazy as it sounds. Sometimes you need your reader to work in directions it wasn’t designed for. The short answer is yes, you can make a reader read “backwards” , but it depends on what you mean by backwards—physical direction, signal polarization, or data order. Let me walk you through the options.

The Short Answer: Depends on What “Backwards” Means

How can I make a RFID reader read backwards? That depends entirely on your situation. If you need the reader to physically read tags behind it, you can aim the antenna differently or add a second antenna. If you need to read tags that are oriented the wrong way, you might need polarization switching. If you need the data itself to come out reversed, that’s a software setting. Each approach works, but they’re different solutions for different problems.

Physical Backwards: Reading Behind the Reader

The most common meaning of “backwards” is wanting to read tags that are behind the reader instead of in front. Standard RFID readers have antennas that project energy in specific directions. Most handheld readers point forward. Most fixed readers point where you aim them. But how can I make a RFID reader read backwards physically?

Aim the antenna differently. This sounds obvious, but people forget. If your reader has a separate antenna, you can literally turn it around. The signal projects straight out from the front of most antennas . Point it backwards, and you read backwards. Zebra’s documentation makes this clear: “By aiming directly at the tags you are attempting to scan you will see much faster read rates” . Same principle applies—aim where you want to read.

Use multiple antennas. Some readers support connecting two or more antennas. You can point one forward, one backward, and switch between them electronically. The ST25RU3993 reader from STMicroelectronics has APIs that let developers control antenna selection and even implement custom protocols . You could literally have one antenna facing each direction and toggle as needed.

Bistatic configuration. Motorola has a patent on a bistatic RFID reader where the transmit and receive antennas don’t point in the same direction . Their design creates an intersection zone where the two antenna lobes overlap. Tags outside that overlap show significantly reduced signal strength. You could theoretically set this up to read “backwards” by having the receive antenna pointing where the transmit antenna doesn’t—creating a weird but functional reverse read zone.

Polarization Backwards: Reading Perpendicular Tags

Sometimes “backwards” means the tag is oriented perpendicular to your reader’s signal. This is a common problem with linear antennas. A linear RFID antenna sends radio waves in a straight line, in one fixed orientation—either horizontal or vertical . If your tag is rotated 90 degrees from that orientation, your read rate drops to nearly zero.

How can I make a RFID reader read backwards in terms of polarization? Research shows that when a linearly polarized reader antenna and a linearly polarized tag have a 90-degree angular deviation, radio communication is generally not possible . The test data shows the reader could only read in a narrow frequency range, and at those frequencies, read distance dropped to about one meter . Basically, the tag can’t get enough energy.

The solution is polarization switching. Some readers have dual-polarized antennas. The patent from 2008 describes a handheld reader with both horizontal and vertical antenna elements . A sensor detects whether the reader is oriented horizontally or vertically, and an RF switch automatically selects the correct antenna element. So if you hold the reader “backwards” or sideways, it still transmits with the right polarization.

The RF IDeas pcProx reader even has configuration options for reversing data order, inverting Wiegand data, and reversing byte order . That’s useful if your “backwards” problem is actually about data format, not physics.

Electronic Steering: Aiming Without Moving

Here’s where how can I make a RFID reader read backwards gets high-tech. What if you could steer the beam electronically without physically moving the reader?

Phased array antennas can do exactly this. By carefully controlling the timing of signals sent to multiple antenna elements, you can steer the combined beam in different directions . The Boeing Company holds a patent on a portable RFID reader that uses an active antenna array with multiple elements, plus circuitry that analyzes sum and difference signals to determine exactly where a particular tag is located .

The reader can then tell you which way to go, or even steer the beam to track the tag as you move. So if you need to read a tag that’s physically behind you, the reader could electronically steer its beam backward without you turning around.

Signal Backwards: Understanding Backscatter

The term “backwards” has a technical meaning in RFID that might confuse things. RFID communication literally works through backscatter—tags reflect the reader’s signal back to it . So in a sense, every RFID reader reads “backwards” by listening to reflected signals.

The Olin College RFID exploration project explains this well: “Using the sent signal as both a power source and a clock, the RFID tag flips a transistor in a predefined sequence… to send a sequence of HIGH and LOW values through the backscattered signal back to the reader” . The tag doesn’t generate its own signal. It just reflects the reader’s signal in a pattern.

So if you’re asking how can I make a RFID reader read backwards in the sense of “how does it receive reflected signals,” the answer is that’s how it always works. You don’t need to do anything special.

Data Backwards: Reversing Bit Order

Sometimes “backwards” means the data itself needs to be reversed. Some systems read card data in reverse order, and you need to configure your reader accordingly.

The pcProx reader from RF IDeas has specific configuration options for this. Under the Wiegand tab, you can “Reverse Wiegand data” which reverses the order of Wiegand bits—primarily used for Card Key proximity cards . You can also “Reverse bytes” to read card data in reverse byte order, useful with MIFARE CSN readers .

So if your question how can I make a RFID reader read backwards is about data format, check your reader’s configuration software. The setting probably exists.

Real-World Testing Results

I’ve seen some interesting data on how orientation affects reads. One study tested RFID tags at different angles and found that read angle and tag orientation matter more at UHF than lower frequencies . A tag that reads perfectly at one angle might disappear entirely if rotated 90 degrees.

The same study showed that with a 90-degree angle between reader and tag, the reader only worked in a narrow frequency range—900MHz to 909MHz instead of the full band—and read distance dropped to about one meter . That’s a dramatic difference.

For handheld reader localization, researchers found that “depending on the orientation of the reader and its antenna, the received signal strength indication (RSSI) of the reference tags showed different patterns as the handheld reader was moved along the path” . They also noted that “the polarization of the reader antenna also affected the detection of the reference tags” . So orientation matters, and you can use it intentionally.

Practical Tips for Backwards Reading

If you need to make your reader work “backwards,” here’s what helps:

For physical direction: Use external antennas you can aim separately. Some readers support multiple antennas—point one forward, one backward. Test with a tag walk to confirm coverage .

For polarization problems: Get a reader with circular polarization or switchable linear polarization. Circular antennas work better when tag orientation varies . Linear antennas give longer range but require alignment.

For electronic steering: Look into phased array systems if you have budget and complex needs. Not cheap, but powerful.

For data reversal: Check your reader’s configuration software. Many readers have settings for reversing bit order, byte order, or Wiegand data .

For general troubleshooting: Remember the Cykeo advice: “Before committing to a full deployment, I always run a ‘tag walk test.’ Hold a tagged item and walk slowly through the read zone at different angles. You’ll immediately see whether the polarization is a good match. This five-minute test can save you weeks of troubleshooting later” .

Common Questions About Backwards Reading

Can I make my handheld reader read tags behind me? Not easily unless you have an antenna that radiates in both directions or you turn around. Most handhelds project forward. Add a second antenna if your reader supports it.

Does turning the reader upside down change polarization? Yes, if you have a linearly polarized antenna. Some readers have sensors that detect orientation and switch polarization automatically to compensate .

Will reading backwards reduce range? Usually yes. Signals are optimized for the intended direction. Reading off-axis typically reduces effective range .

Can I reverse the data from a card? Yes, many readers have configuration options for reversing bit order or byte order . Check your settings.

What about through-metal reading backwards? That’s a different problem. Metal blocks RFID signals regardless of direction . You need on-metal tags, not backwards aiming.

The CYKEO Approach

At CYKEO, we get asked how can I make a RFID reader read backwards in many forms. Sometimes customers need to read tags on the other side of a pallet. Sometimes they need to handle tags applied in random orientations. Sometimes they just want to understand how backscatter works.

Our readers incorporate features that help with all these situations. Some models support external antennas you can position anywhere. Others have circular polarization that reads tags regardless of orientation. And our configuration software includes options for data formatting that let you handle reversed bit orders.

We also emphasize testing. Every environment is different. What works in a lab might fail in your warehouse. Run tag walks. Try different angles. Move antennas around. The five-minute test saves weeks of regret .

The Bottom Line

How can I make a RFID reader read backwards? It depends on what “backwards” means to you.

For physical direction, aim antennas differently or add more antennas. For polarization problems, use circular polarization or switchable linear antennas. For electronic steering, explore phased array systems. For data reversal, check your configuration settings.

The key is understanding that RFID signals have direction, polarization, and data formats—all of which can be adjusted. You’re not stuck with default behavior. With the right equipment and a little experimentation, you can make your reader work in ways that seem “backwards” but actually solve real problems.

And remember—when all else fails, sometimes the simplest answer is just turning the reader around.

---

Long-Tail Keywords (Integrated Naturally)

• rfid reader reverse direction – covered throughout the physical aiming discussion above
• rfid antenna backwards aiming – addressed in the antenna positioning section
• reverse rfid tag reading – featured in the polarization and data reversal sections
• rfid beam steering backwards – explained in the electronic steering section