how do you build a two way radio antenna that is the frequency 460 - 470 mhz
- Thread starter johnson 2
- Start date
D
Decade
- Jan 1, 1970
- 0
Hi johnson 2!
Are these two way radios handheld or base units?
What kind of connectors for external antenna do they have and what is the output power from them?
Are these two way radios handheld or base units?
What kind of connectors for external antenna do they have and what is the output power from them?
D
Decade
- Jan 1, 1970
- 0
Hi johnson 2!
It might be possible to solder a coax cable to the PCB were the antenna is connected but it is not that easy, you got to find where the ground is on the PCB and hopefully the impedance is 50ohms.
A dipole is 1/2 wavelength, formula: antenna length in meters=150/(frequency in Mhz that the antenna is intended for) if you wish a 1/4 wave antenna simply divide the result with 2.
Impedance of a 1/2 wave dipole is about 75 ohms and a 1/4 antenna with groundplanes can be tuned to 50 ohms by adjusting the angle of the groundplane.
Just a warning.. by doing these changes you can kill the power amplifier in you hand held transceiver.
It might be possible to solder a coax cable to the PCB were the antenna is connected but it is not that easy, you got to find where the ground is on the PCB and hopefully the impedance is 50ohms.
A dipole is 1/2 wavelength, formula: antenna length in meters=150/(frequency in Mhz that the antenna is intended for) if you wish a 1/4 wave antenna simply divide the result with 2.
Impedance of a 1/2 wave dipole is about 75 ohms and a 1/4 antenna with groundplanes can be tuned to 50 ohms by adjusting the angle of the groundplane.
Just a warning.. by doing these changes you can kill the power amplifier in you hand held transceiver.
D
Decade
- Jan 1, 1970
- 0
Here's a link to a 1/4 wave antenna in Swedish though ;D
http://www1.shellkonto.se/icom2002/pmr/2/index.htm
Lengths L1-L5 160mm but usually ground planes (the 4 down going wires) are made 5% longer than the vertical pin. If you are familiar to the chassie connector SO234 you know that there is 4 holes for mounting, these holes are used for the ground planes, you simply solder 1,5mm brass or copper wire into the holes.
Good luck!
http://www1.shellkonto.se/icom2002/pmr/2/index.htm
Lengths L1-L5 160mm but usually ground planes (the 4 down going wires) are made 5% longer than the vertical pin. If you are familiar to the chassie connector SO234 you know that there is 4 holes for mounting, these holes are used for the ground planes, you simply solder 1,5mm brass or copper wire into the holes.
Good luck!
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