I have done some research about “Emergency" VHF vertical antenna that can work around 145 MHz.
The concept is I need to find the antenna that simple , easy (to make,to calculate,to understand) and fast to built when emergency situation comes.
I already tried to made the dipole antenna from RG-58 coaxial cable (Ref : https://youtu.be/tafy51yUzQo) but won’t work because the braid (shield that roll back to act as the radiator) is too loose and the length are alway change.
May I have any suggestion ?
Thank you for further answers.
use the braid as the antenna, not the centre conductor. You don't need to strip it off and can fix it to the centre-conductor at both ends so it doesn't unravel. It will have a wider bandwidth (and slightly shorter length) than the narrow centre conductor.
If the braid is too loose you can wrap it in copper tape to strength it.
Watchara Amasiri 1/4 wavelength vertical monopole with a ground plane from 4 radials of ~1/4 wavelength bent at 45 degrees down should do the job.You need a UHF (F) panel mount connector (4 holes on flange) with monopole soldered to it and nut-bolts to screw the radial wires. All wires can be stiff copper that allows soldering/ twisting to enable screwing and adjusting the angle.
A standard coax goes onto the UHF (F) connector. The stiff wires are ~ 50 cm (1/4 lambda) and may be transported straight as well.
A practical antenna that works, is robust, and low-cost.
use the braid as the antenna, not the centre conductor. You don't need to strip it off and can fix it to the centre-conductor at both ends so it doesn't unravel. It will have a wider bandwidth (and slightly shorter length) than the narrow centre conductor.
- Badges
- Science topic