Rfid Antenna

The tracking of documents at a law firm?
An EAS system for a power plant?
Inventory logistics for a small waehouse?

Actually, to choose the best antenna fo rthe application you need to take a closer look at the desired process, whether to track documents, as an EAS system, or in a warehouse.

If I needed to track documents traveling through a doorway or portal, I might use a high gain, circularly polorized antenna, because ther is little control over how the document is being carried through by a person and I would need the gain to maximize sensitivity and the circular polarization because I do not know the RFID tags orientation with respect to the fixed antenna as it passes by. If I was setting up a desktop check out station, where someone "swipes' the document as he passes, I might use a much lower gain antenna, with possible a slot design, nearfield design or other polarized antenna, so that I only read the specific document taht I place in the read zone, and not all the other nearby documents.

An EAS system, to detect when either equipment or personnel pass through a zone will probably require circularly polarized antennas, at high gain, and set up through a doorway or portal from 2 sides and probably the top as well. Possibly even multiple antennas on each side and also teh top, depending on the doorway's width. The intent would be to "burn through" any blocking substance, such as a human, briefcase or other. Also, the circular polarization and antennas from multiple positions because the orientation and position of the tags is random and uncontrolled.

Inventory logistics in a warehouse require extensive analysis of the desired process before selecting an antenna or other parts of an RFID system. At what points do things need to be read?, cases, pallets, item level or what? How stored, stacked, shelves, etc. Moved by hand, or always by a forklift?
Dock doors, or out through a normal door? Hand scanning with a handheld RFID reader or totally automated? What are the material being tagged made of, metal, wood, plastic. cardboard? All of these things will factor in to determine the best solution

Various antennas would be used in different parts of the process. In addition, selection of the tag types to be used is also critical.

Good luck!

2008-06-07 11:15:30 by Paul W

Installation amp; Tuning Tutorial for the 18-Port Roulette Table RFID Antenna

Describe the advantages and disadvantages of your selection. What type of connection would be utilized to communicate with the middleware application?

It should be located away from the metal forks of the forklift, both the horizontal and vertical portions of the forks.

I would locate the interrogator in the middle of the vertical portion of the lift, away from any metal. The tags would then be located on the bundles, in the middle above the palletes, so as to line up with the middle of the vertical portion of the lift.
Advantage: passive RFID chips can be used.
Disadvantage: the tags must still be placed on the loads fairly precisely to line up with the interrogator.

Communications could be wired to a central box in the cab of the forklift, but wireless comm. from fork to cabin would be preferrable.

.

2008-06-22 09:31:08 by Paul W

Price: $2.99

i have a low budget.i want to keep the reading distance atleast 20cm.

Any of the conductive metals would work for antenna material - aluminum, copper, silver, etc. A lower resistivity material is better than a high resistivity material, but most metals would work. This would give you flexibility in your design, and keep the costs low. The point is: there is nothing special about the material for the antenna - any reasonably conductive metal will radiate/receive radio waves when electrical currents are oscillated within the metal at 13.56MHz.

Tuning is both simple and complicated: the simple part is a basic dipole antenna arrangement in resonance will radiate the radio waves just fine - the "tuning" aspect "shapes" or directs the radiated field; this will give you improved 'gain' relative to the dipole in the way you want; after tuning is completed it is the amplifier and power input that will determine how far the useful field radiates from the final antenna design. The formula to convert a 13.56MHz frequency to a 1/4 wavelength antenna is in the antenna design links below (comes out to 17ft. 3 - 3/32inch for each arm of the dipole.) 17 feet is pretty long, so you're probably going to want to look at compact antenna designs.

TV antennas operate at only slightly higher than 13.56MHz, so you may want to look over the wealth of information available for TV antenna design to get some inspiration.

The amplifier design for resonance is a little more tricky and may take a little more time; especially if you don't have a budget for or can't borrow/use measurement equipment.

I think if you get the equipment and get started you'll probably be successful, and with patience, if you tweak the design you'll be able to make improvements and optimizations over the basic design. Part of the equipment that would be helpful is an oscilloscope that can work at these frequencies, so you can measure what you're doing, but 13.56MHz is just outside the low frequency range, so the cheap measurement tools won't work well for you (something to confirm before spending money).

2006-06-18 23:14:26 by r.jo

Price: $9.95 $9.95

please anyone help me to design antenna for RFID tags(passive). The antenna should be as small as possible at the frequency of 13.56MHz.Also it should possess read range as gar as possible. Please tell me the ways to design for the least geometry of the antenna. Also tell the details of the antenna type u propose.
Please do it for me & i will be greater for you .

usually small antennas do not have very good distance.

the maker of the RFID chips will have a good design, they have balanced antenna size with good range, and that is not easy to do.(probably why you asked the question)

start somewhere like here to learn how to do it.
http://www.dxzone.com/catalog/Antennas/T heory/

but you will usually see that is is easier to buy and then copy what the manufacturers have done.

at 13.56c.p.s. I would suggest using a ferrite core, just using the magnetic part of the EM wave can sometimes work really well and it is quite small when compared to other designs.

there are so many ways to do it,

it would help to answer your question if I knew the largest antenna you could tolerate, does it need to fit in a van or your pocket or way smaller than that ?
what distance are you looking for ?
a few inches, or a few hundred meters ?

2007-06-30 11:07:05 by Kavi

Books can be written on this subject.

Since it is so broad, consider the following when designing a RFID tag.

Know the conditions that tag is expected to perform under: physical assaults, temperature conditions and changes, what it will be attached to, etc.

Signal frequency affects its propagation. Lower frequencies tend to bounce while higher frequencies tend to go through objects.

Initial power of a signal affects is ability to exhibit the aforementioned properties.

Ferrous materials too close to the antenna can electrically extend the antenna length, unbalancing the signal.

Liquids tend to deaden signals.

High electrical power, arcing electricity, and even high strength signals that are close can affect a signal.

2008-06-14 09:13:12 by Paul W