Warning: The use of gain antenna in some countries is not permitted. Similarly where ERP (transmitted power limits) are imposed the actual transmitted power must not exceed the limit stated. This means that the transmitter output power, less any coaxial feeder losses, plus the antenna gain must not exceed the specified maximum ERP. Before installing your system please check!
Antenna Types
Antenna types fall into a number of categories. For the majority of applications the choice lies between portable, fixed,
True
Whatever antenna types you choose please ensure that its impedance is 50 Ohms.
name | Gain and Directional Properties | Comments |
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1/4 wave dipole | < | For portable apparatus operating above 400MHz |
| vertical plane only. | Requires a ground plane for operation |
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Helical | < | For portable apparatus < 400MHz |
| vertical plane only. | Requires a ground plane for operation |
|
|
|
1/2 wave dipole | + 1.2 to + 1.8dB near omni- | For portable and fixed apparatus looking for a low |
| directional in the vertical plane. | cost antenna that does not require a ground plane |
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End fed dipole | 0db, near omni in vertical plane | For fixed apparatus that does not require a ground |
|
| plane |
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Colinear | +3dB to +9dB , near omni- | For fixed apparatus that does not require a ground |
| directional in vertical plane | plane |
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Yagi | +3dB to +28dB . Beam width | For point to point links. Where an unwanted signal |
| proportional to gain | needs to be blocked from the opposite direction |
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| choose an antenna with a high front to back ratio |
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