How Can You Gain From Gain, When You Don’t Know What I’m Talking About?
Hello for 04-2000
By: Mike Lipshultz

If you have ever shopped for an Antenna (for a TV, Cell Phone, CB Set, or almost any other “Radio” type device) you probably have heard the word “Gain”.  Like “this antenna is high Gain”.  Now most people think any antenna that is a “High Gain” is better then one that is not.  But in reality the best antenna for any given device is the one best suited for the area that it will be used in.  In fact a “High Gain” antenna dose not increase the strength of the signal or make it stronger in any way.  It just “receives” the signal in a different way than a none gain antenna.  And that is not always better.

Now that I have you totally confused let me give you some information taken straight from the web site of a company called Andrew.  Andrew ( ) is a company that, among other products, designs and manufactures antennas.  Their site has the best explanation of “Gain” I have ever seen.  So here it is:

Q. What is gain?
Gain is a measure of how much of the total power of the antenna is radiated. Gain does not equal power. The power of the signal is determined by the phone. There are generally three types of gain for cellular and two types for PCS. It is easiest to think of a fully inflated beach ball when thinking about gain.

0 dB means that equal amounts of the signal are being radiated horizontally and vertically. Think of the beach ball when it is fully inflated. It is the same size all the way around. This type of antenna is good for use in urban areas with tall buildings and obstructions.

3 dB means that more of the signal is radiated horizontally than vertically. Again, think of the beach ball. Instead this time, you place your hands on the top and bottom and apply pressure. The shape of the beach ball is flattened, but it has not lost any air. The same applies to gain; the signal strength is not changed, just flattened. This type of antenna is good in suburban areas. This is considered the most universal antenna.

4 dB means that most of the signal is radiated horizontally and very little is radiated vertically. Again, think of the beach ball. Apply even more pressure to the top and bottom. This will flatten the ball out even more. This type of antenna is good in rural areas.

Q. What type of gain is best?
A. There is no best type of gain. It depends on where you will be using the antenna. If you are looking for an antenna to use in all areas, we would recommend the 3 dB antenna. If you are usually in a city or an urban area, 0 dB antennas are good. If you live in a rural area, 4 dB antennas are better.

Q. Some antenna gain measurements are listed as dBd and some are listed as dBi. What is the difference and which is better?

A. All antenna gain measurement are relative to something else. DBi is a measurement relative to a theoretical isotropic radiator. This is considered, to a point, antennas that radiate in a perfect spherical pattern of energy. An easily visualized, but impossible to build device.

DBd is measured in relation to a center-fed half wave dipole antenna. This is one of the simplest antennas to construct and is a convenient standard of measurement. At Andrew Wireless Products, all antennas are measured in dBd. Don’t be fooled by some listings that give a dBi measurement; many manufacturers use dBi to get a higher gain number for their antennas. In reality, the gain measurement is lower than stated.

Now hopefully you have a better understanding of just what “Gain” is.  Now check out Andrew's enterer Web Site at:


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