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Neutron2014-08-07 17:03:12
Neutron, 2014-08-07 17:03:12
How to convert a 890 MHz directional antenna to 430 MHz?
Good afternoon.
I have a directional antenna like this: 
This is ARN-824 CDMA 824-890 MHz (14dB).
There was a need for an antenna for MTS Connect 430 MHz.
Is there any way to remake it at home? If so, how?
Thank you very much in advance.
2 answer(s)
@throughtheether
Calculate an antenna of the "wave channel with a loop active vibrator" type for the desired frequency range. Make an active vibrator (in the photo - a loop where the cable is connected), a reflector (the longest crossbar), directors (the rest of the crossbars). Install them in the desired positions on the traverse (the base where everything is attached). Since the corresponding wavelength increases with decreasing frequency, the linear dimensions of the elements, it seems to me, will increase, so it may turn out that even the traverse will need to be changed. After assembly, match the resistance (having achieved normal SWR).
If you need an antenna, it's easier to buy a ready-made one for the desired range. If you need to redo this antenna, then I briefly outlined the plan for you.
I may have been too perfectionistic. If I were in a situation where I really need to drag the antenna to another band with minimal resources, I would (personally) try:
0) plug the antenna into the modem at random, I doubt very much that the transceiver will burn out from this (most likely there will not be enough power ; but accidents cannot be ruled out).
If the miracle did not happen (the reception did not improve), then I would try to redo the antenna in the first approximation:
1) increase the reflector (should be strictly greater than λ / 2, as far as I remember)
2) increase the distance between the active vibrator and the reflector, the active vibrator and the first director to the calculated (about λ / 4)
3) throw out the extra directors, as @Lerg explained in the comment, to fit everything on the old traverse.
T
throughtheether, 2014-08-07 @throughtheether
Is there any way to remake it at home? If so, how?
Calculate an antenna of the "wave channel with a loop active vibrator" type for the desired frequency range. Make an active vibrator (in the photo - a loop where the cable is connected), a reflector (the longest crossbar), directors (the rest of the crossbars). Install them in the desired positions on the traverse (the base where everything is attached). Since the corresponding wavelength increases with decreasing frequency, the linear dimensions of the elements, it seems to me, will increase, so it may turn out that even the traverse will need to be changed. After assembly, match the resistance (having achieved normal SWR).
If you need an antenna, it's easier to buy a ready-made one for the desired range. If you need to redo this antenna, then I briefly outlined the plan for you.
I may have been too perfectionistic. If I were in a situation where I really need to drag the antenna to another band with minimal resources, I would (personally) try:
0) plug the antenna into the modem at random, I doubt very much that the transceiver will burn out from this (most likely there will not be enough power ; but accidents cannot be ruled out).
If the miracle did not happen (the reception did not improve), then I would try to redo the antenna in the first approximation:
1) increase the reflector (should be strictly greater than λ / 2, as far as I remember)
2) increase the distance between the active vibrator and the reflector, the active vibrator and the first director to the calculated (about λ / 4)
3) throw out the extra directors, as @Lerg explained in the comment, to fit everything on the old traverse.
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