VOCABULARY
Before you begin this journey, there are a few terms with which you need to become familiar. First and foremost is the term RF. The literal meaning of RF is Radio Frequency. However, it is more often used in its figurative sense as both a noun and an adjective. You can generate RF (a noun) or you can generate an RF signal (an adjective). (RF can also be used to describe a range of frequencies, but more about that later.) As will be explained shortly, when used in this book, it is best to think of RF as an electrical signal which is on the move.
Prefixes
Next, you will need to know the prefixes for the powers of ten (remember chemistry?). There are only four of any consequence and they are listed in Table 1-1.
| Prefix | Meaning | Example | Interpretation |
|---|---|---|---|
| milli (m) | 1/1000th | 5 mW | 0.005 Watts |
| kilo (k) | 1000 | 3 kg | 3000 grams[a] |
| Mega (M) | 1 million | 2 MHz | 2 million Hertz |
| Giga (G) | 1 billion | 100 Gigabucks | Bill Gates' net worth |
[a] You don't know what this is yet.
Basic Electronics Terminology
Table 1-1 introduces you to another word you will need to know: watts. Watts are the unit of measure for power. If you don't know what watts are, just imagine touching a burning light bulb. A word related to power is energy, which is power times time. If a 100 watt light bulb burns for two hours, it equals 200 watt-hours of energy. If you want to envision what energy is, just imagine touching a burning light bulb for two hours. A word of caution, though—in the strange world that is RF, the words power and energy are often used interchangeably.
Two words closely related to power and energy are voltage and current. Voltage is just an electric potential, and there are two kinds: AC (alternating) voltage is the type found in a wall outlet; DC (direct) voltage is the type found in a battery. Current is simply electrons on the move. Like voltage, current can also be made either alternating or direct. The exact relationship between voltage, current, and power is simple: voltage times current equals power.
An important word related to current and voltage and one used quite often is circuit. A circuit is an interconnection of a bunch of electrical stuff. Electrical circuits are sometimes manufactured on something called printed circuit boards (PCB). If you have ever seen the inside of a computer, VCR, or any other electrical appliance, you have seen a PCB. It is just a hard, thin, plastic board with electrical stuff mounted all over it.
A word you will see occasionally is microwaves. It is often used inter-changeably with the term RF, but is mostly used to describe a range of frequencies. Millimeter wave(s) is also used to describe a range of frequencies.
You have probably figured out by now that the word frequency is very important in the world of RF. This word will be explained in detail later, but its importance cannot be over-emphasized. If you are going to understand the concept of RF at any level, you will eventually need to grasp the concept of frequency. If you already understand what frequency is, you've got it made. If you think it has to do with how often something occurs, you're right. Stay tuned.
Since I'm going to be using the cellular phone to explain how RF things work, another word you will want to be familiar with is basestation. Cellular basestations consist of, among other things, those blue or gray steel towers by the side of the road which are owned by the cellular providers and are used to communicate with cellular phones.
In the world of RF, all terminology eventually gets replaced by its acronym, and so it shall be in this book. After a concept is explained and the acronym noted in parentheses, the remainder of the book will use the concept and the acronym interchangeably. Cheer up. By choosing to use acronyms, several hundred pages are eliminated from your reading. Not to worry though, Appendix A contains nothing but acronyms to help you navigate the waters.