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My best omni antenna
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two small RG174 coax connect the new diversity antennas, the old get disconnected.
why this design...?
Gain & efficiency: An antenna that radiates poorly has
a low gain. This gain is a measure of how strongly the
antenna radiates compared to a referenced antenna system, such like a dipole ---> dB (d) for dipole ...!
An antenna that is 12db less than a dipole is -12 (d) !!! and would offer 1/4 of range of a dipole.
Small and compact antennas like build on PCB are often less efficient than a dipole design and offer a
negative gain like my examples below.
Exaples based on PCB:
| Antenna system | Gain over dipol dB (d) | used | direction |
| Printed Open Stub | -8dB | over 800 Mhz | omnidirectional / vertical |
| Short Printed Stub | -12.5 to -14dB | from ~ 315 Mhz | fairly omnidirectional |
| Open Slot antenna | -4.5 to 6dB | over 800 Mhz | omnidirectional / vertical |
| The Trapezoidal Patch | -12db | over 800 Mhz | directional / vertical |
Exaples:
| Full size Whip L/4 | 0db | all | vertical |
| Dipole | |||
more soon ....