Gain? No not the soap

[SCPD]

antenna gain? I have been told I need a good antenna with lots of gain for my PRO-106 Scanner. Question is why? Can someone explain SLOWLY for me. I am a scanner hobbyist, but for the enjoyment my wife and I get from listening... I am lost when it comes to tech stuff.

 

[W6KRU]

Here is pretty good summary of gain. If you need to know more, come on back and ask questions.

Antenna gain - Wikipedia, the free encyclopedia

 

[n5ims]

The WIKI article has good information, but is pretty heavy on math and theory. For a pretty basic description of how the various types of antenna designs generate their gain, I like the doughnut explaination like in this old post http://forums.radioreference.com/sc...fusion-mobile-antenna-related.html#post912334

One thing to think about with a simulcast radio system is the distortion most (probably all to at least some extent) scanners have is getting too much signal (yes, that's correct, they can get too much signal) and mix the various tower's signals causing what appears to be too little signal strength. In this situation, a lower gain antenna may work much better than a high gain one. Even better (in a fixed location) would be to get a very directional antenna like a yagi and point it so only a single tower's signal will be picked up (it may not be the closest tower, but one located where no other of the system's towers are in the pick-up pattern).

 

[W6KRU]

You are absolutely correct John. I didn't intend for the OP to read all of that theory and math. If I had a chalkboard I would have done a drawing of the doughnut to start with. That is how I picture antenna gain. The advice on the gain antenna for simulcast is good stuff as well.

 

[K9WG]

Think of it as a light bulb. When the bulb is lit, light goes everywhere. If you place a reflector behind it the light is concentrated but at the expense of shining uniformly around. Antennas are very similar. An antenna with unity gain will radiate (or receive) equally in all directions (think of the pattern as a doughnut laying on a table) . If you narrow the radiation pattern you can create an effective gain as in a beam antenna. You can also in effect do this by flatting the doughnut and achieving an omnidirectional pattern with gain. Antenna gain is expressed in decibels (dB).