"Are there any cost-effective options for eliminating bounce reads of passive tags? The one supplier I found wanted $115 per square foot, which would not be practical for most portal installations.
There are a variety of ways to deal with stray reads. You may be able to turn down the antenna gain to reduce the reader's range without affecting your ability to read tags coming through the portal. Another option, if you know what tags are expected to come through the portal, is to use software to filter out stray reads. In other words, if you know that only tags with serial numbers starting with 123 should be going through the portal on a given day, then you can filter out or ignore tags that start with 345."