In April, 1992, Allflex and Texas Instruments formed a joint venture to develop a new electronic ear tag for use in livestock identification. This new tag would incorporate the world wide accepted ear tag attachment system from Allflex with the new TIRIS half-duplex radio frequency transponder system.

The founders of this new electronic ear tag project were far sighted enough to realize that the ear tag was only one piece of an identification system. New reading systems to read or interrogate the tag would have to be developed as well. The new electronic ear tag would only be as good as the reading system that could read it.

As the electronic ear tag was being processed through prototyping and field trials, a simultaneous program was underway to develop an improved tag reading system. Electronic tag reader systems are generally either stationary or portable. First we will address the stationary reader issue, followed later by the portable or hand held systems.

A stationary reader system is made up of four components: an RF module, an antenna, a control device (computer) and software. Texas Instruments had already developed an excellent stationary RF module called the S-1000, along with four basic antenna designs. These antenna were of the flat frame or 2D construction. In field trials of large animals it was determined that these antennae did not provide an acceptable number of reads. Too many animals could get by the antennae without being read.

It was determined that a walk through or portal antenna should provide a reading field that was dense enough to obtain the desired reading efficiency. Since one of the major markets for the new electronic ear tag was the cattle market, a portal antenna that could accommodate a full grown cow or bull was developed.

This antenna (Figure 2) has an interior opening of 34 inches wide by 68 inches high. One of the many hurdles to overcome with this design was efforts in the past by others to develop an effective antenna of this size had not been successful. Even RF engineers with Texas Instruments were skeptical of this project.

To make a long story short, Figure 2 is a drawing of the new Allflex defended structure portal antenna. This is a commercially available unit that is in stock today at our Dallas facility. It is a stand alone structure constructed of a fiberglass reinforced polyester plastic tubing material similar to the wing construction of modern day fighter planes. The design criterion was that the unit would be able to stand up to the normal and abnormal abuse by large animals found in a dairy or feedlot. It uses the standard TIRIS S-1000 RF reader module with a special Allflex designed antenna system. This unit has been granted FCC approval as it is configured.

Figure 3 represents a 3D view of the outer limits of the field surrounding the portal antenna as an Allflex electronic ear tag is moved with favorable orientation toward the structure. This plot was measured on one inch grid intervals along the X and Y axis of the antenna in a relatively quiet EMI area. Notice the distortion of the field vertically in line with the antenna wiring located in the upright tube frames. Note also that two fields of interrogation exist, one in front of the structure, and one behind. This provides the reader module with two opportunities to read the tag as the animal moves through the portal.

Figure 4 shows a view of the field as plotted directly in front of the portal antenna. Note here that no null or dead zones exist with the electronic ear tag in the most favorable position. In the least favorable position, null zones of very minor size can exist.

Referring to Figure 4, one of the difficulties encountered with the Allflex portal system is that the field exists outside the outer most part of the structure. Because of this an animal with an electronic ear tag outside the portal will be read if it enters into this outer field.

One method to prevent these missed or double reads is to use some type of external shielding. It is common knowledge that if a metal plate is positioned next to an antenna, the field can not penetrate the metal; therefore an electronic tag on the opposite of the plate would not be read. The simple solution of placing metal walls along side the portal antenna was not without its pitfalls. Any metal object located within the limits of the reading field will cause the field to change shape. Generally, it will cause the field to decay which will cause a drastic reduction in the reading range of the antenna and the creation of large null or no read zones will occur in the portal opening. Any tag moving through one of these zones will not be read.

Again, efforts to obtain information from existing sources pertaining to the subject of antenna shielding were met with vague references that were incomplete or did not agree with our existing knowledge base.

After many man-hours of effort and experimentation, Allflex has developed a effective shield methology that totally eliminates penetration of the shielding by the reading field, and at the same time actually complements or enhances the development of the reading field within the walk through area of the antenna. Much of this enhancement is due to the shield blocking the effects of external RF interference. A shielding system installed at a research dairy in Illinois has reduced the incidence of miss or double reads of electronic tags to zero.

Texas Instruments was recently released a new RF reader, the S-2000. Allflex is currently in the process of developing a portal antenna system utilizing multi-phased antennas to fully utilize the potential this new reader will offer. As soon as development and testing is complete, FCC certification of these types of systems will be sought.

A portable or hand held reader is made up of the same basic four components: an RF module, an antenna, a control device (computer) and software. Again, Texas Instruments had developed a very rugged portable reader called the HHU or hand held reader. This unit could be connected with an RS232 cable to a lap top computer and the entire assembly could be called portable. The major problem encountered with this type of arrangement was that the lap top computers generally would fail in the field especially if subjected to harsh environments such as a feed yard or swine operation and the entire assembly was not very portable.

It was obvious after several field trials that a more satisfactory system was needed. The initial objective was to develop a hand held computer with the RF module and antenna integrated into the internal circuity of the computer. A review of hand held computer manufacturers netted only a few with any interest in this project. One company, Husky Computers Ltd., Conventry, England, was very interested and took an immediate role in this development of a new hand held computer. Using their recently introduced FS/2 computer (Figure 5), several different methods of integrating the RF module and antenna into the computer were tested and evaluate. It was decided that in order to maintain the high standard of IP67 the Husky FS/2 is produced to an external RF module with antenna was the most effective method of marrying the RF technology to the computer. As a result of that decision, Husky developed in less than nine months the Allflex electronic reader gun (Figure 6).

This external reader will connect with any Husky computer via a circular 12 pin RS232 mode connector. Later developments with allow adaptation to any PC or lap top computer that can provide the correct operating power source. The gun reader uses a trigger method to activate the reading sequence and provides both audio and visual indicators of a captured tag read. The gun also enjoys an IP67 rating as the computer (Figure 7).

The FS/2 is a unit that is designed for extreme field use under all conditions. It uses an 8088 processor based architecture using the NEC V25+micro-controller. It is a MS-DOS based machine using Ver 3.30. With its large memory capacity of up to 4 MB of ram, it can handle a wide spectrum of software programs. Additional information on this unique system is available and due to the short time allowed, it can not be discussed in detail.

As Allflex has proven in the past that it is a pioneer and leader in the visual animal identification industry, Allflex Technologies is proving that it is a pioneer in the field of electronic animal identification systems.