Look for lots of dark red in the radiation pattern. The Alien H-plane is an example of the perfect response: At every distance and every orientation, we were able to read a tag 100 times out of 100 attempts. In contrast, the Symbol H-plane shows lots of dark blue, which represent distances and orientations in which the tag is unreadable (zero out of 100 attempts).

Based on our tests, there are two ways to measure the quality of the tag. For the farthest read distance, look for the biggest circle that has red on it. For orientation sensitivity, look for circular patterns, such as those in the Symbol H-plane, which are ideal because the tag will perform the same regardless of how it is rotated in that plane. But the Symbol E-plane shows that the tag has two large angles, or null zones, in which it is unreadable even 1 foot away.

Color code for response rate: We plotted our test results using a color-coded radiation pattern. The colors correspond to the percent of responses at a distance and orientation.

Overall, we saw a set of tradeoffs, with no clear winners and losers. The Alien ALL-9334 was clearly the best performing tag, but its size—by far the largest tag we tested—makes it unsuitable for many item-level applications. Still, it does emphasize an important general principle: Bigger tags, in general, perform better, because antenna performance is roughly proportional to the size of the antenna.

The performance we observed with this tag is comparable with that of tags with a 1-by 4-inch form factor, such as the Alien Squiggle. The ALL-9334 has a nearly perfect radiation pattern in the E-plane with very small null zones (the null zones are likely to become more pronounced at larger distances, which should not be a concern for item-level tags). The H-plane performance was ideal.

The read distance of the Avery AD-010 was good, not great, practically limited to 3 feet. But the real benefit of this tag is its radiation pattern. While the radiation pattern isn't circular in either plane, perhaps more important, there is only one large null zone in the H-plane. There are many small null zones, but they are comparatively narrow, which is, in general, more desirable than large null zones.