First, a definition. A “noun phrase” is not the entire subject of a sentence. Your sentence might be
“The brave, warmly dressed woman holding a saw and the large hawk with a rat in its mouth perch in the tree staring at each other.”
Then the subject has two noun phrases in it. It’s a collection of nouns and adjectives (or even phrases) that have been stuck together to form one long noun. Some other examples are:
power-controlled rate-adaptation interference graph and
wideband, high-resolution analog-to-digital converter.
Here are two places to find more examples: http://www.chompchomp.com/terms/nounphrase.htm and http://www.grammar-monster.com/glossary/noun_phrases.htm.
The common technique in engineering is to stick everything together in one set of adjectives and nouns, and then skip the (helpful, sometimes more explanatory) prepositional phrases. I often want you to unpack the set of adjectives and nouns and use phrases to clarify what you mean. Also, you might discover that you don’t need all that information about the noun; you might already have established this information earlier in the article, and you can just use a shorter name for this thing.
Here’s example that a student brought in last week:
Understanding spin transport via collective magnetic excitations is currently gaining attention.
This is a refreshingly short sentence, but it’s a bit difficult to unpack (by which I mean, “interpret”). In other words, the reader has to turn the words around in his or her head in order to understand what it means. Here are some possible revisions:
Researchers are now trying to use collective magnetic excitations to understand spin transport.
Researchers are trying to understand spin transport by looking at collective magnetic excitations.
Researchers are trying to understand spin transport by looking at the way that collective magnetic excitations influence them.
But maybe none of these is accurate. They might not be what the sentence means at all. I had to make up some possible relationships between the two topics, which would not have been necessary if the writer had clarified that relationship. Often, when I quiz students on what they mean by a sentence, we go though many revisions together before I suddenly realize what they meant, and how far that was from my guess!
Take-away message: beware the long noun phrase. If you find yourself writing one, determine if there’s some information in it that has already been clearly established; then take that part out. If it’s still ambiguous or just hard to figure out, explain the relationship between the various parts of the noun phrase.
Anything you can do to make your reader’s job easier will help assure that they are getting the message you intend to send. It will also get you more readers!