High gain antennas compared to standard antennas

Somebody in our club purchased a couple of 13" long rubber duckie antennas. They work fine but we were hoping for better distances with the bigger antenna. There is talk about using a high gain antennas instead of the 13" ones.

Can you tell me when to use a standard antenna and when to use a high gain antenna.

The Rubber Duckie style is an Omni-directional antennas used where communications between devices are spread all over the place or when distances are small. High gain style antennas like Yagis and Flat Panels are used when distances are greater and communications are between two points or in the same general direction.

Since antennas pick up noise and other RF signals, Omni antennas receive the signal in from one device and also receive interference from a completely different device from a different direction. Flat Panel antennas are very directional receiving signal from a device in one direction and rejecting interference from a different direction. These high gain antennas have increased signal strength in one direction and increased signal rejection in all other directions.

antennas.jpg
The above overhead view RF signal pattern graphics (antenna is in the center) illustrates how the Omni listens in all dIrections equally (red outlines) while the Flat Panel listens only to the right side of the graph and very little from other directions. All the receiving is concentrated in one direction. The same applies to transmissions. Omni antennas send signal in all directions while the Flat Panel antenna focus the same amount of RF power in a concentrated area. The RF signal goes farther with the Flat Panel because more power is aimed in that direction and little power is wasted in unwanted directions.

Thanks for the reply. The graphs may be over my head but I understand the concept of concentrating in one direction.

Коллеги, у кого обычная 9-и элементная антенна- метните описание тоже, не сочтите за труд. А то я, увидя в High Gain, что пред-предпоследний директор короче 2-х последних, теперь тоже точно не уверен в правильном расположении элементов

TRANSLATION:
Colleagues who have the usual 9-element antenna, mark the description too, do not consider it work. And then I, seeing in High Gain, that the pre-penultimate director is shorter than the last 2, now I’m also not sure of the correct arrangement of the elements

I’m also not sure of the correct arrangement of the elements
Orientation and setup of the Yagi-style High Gain Antenna can be viewed on the RaceAmerica website at:

http://www.raceamerica.com/yagi.html