I have reviewed several papers and have seen several odd things happen:
1. Some guys I work with submitted a very good paper on a mixer, but they were rejected and a paper on a similar subject was accepted because it was from someone who has a "name." I am often at paper selection meetings and papers are accepted because of the names of one of the authors, not on the papers merit. Not fair and I don't like it, but it happens. Does your paper run parallel to someone's work? Someone who is well published?
2. Do all the authors report the same results? Usually your paper is passed out to at least three authors. You should see the results of more than one author. The reviewers have two sections to fill out in a review, one for the author to see and one for only the editor to see. Do all of the reviewers comments agree?
3. Do you have any experimental results? Unless the paper is specifically stated to be a paper not requiring any results (and I can think of very few instances) it should be rejected. I don't know how many circuit papers I get where the author designs a circuit, does excellent theoretical development and then only gives simulated data.
4. If the AP rejected this, try the MTT-S. Specifically the IEEE MICROWAVE AND WIRELESS COMPONENTS LETTERS (L-MWC), which used to be known as the IEEE Microwave and Guided Wave Letters. Also the MTT-S transactions would be another alternative.
5. Now that you are aware of the patent, you could re-write the paper to add a section to contrast the differences between your design and the patent and any enhancements you have added. But if you do, you might be ruining a potential patent for yourself!
-Ron