In South America it is somewhat expensive to set up Motus stations, but mainly due to shipping costs and customs. I was wondering whether people in this group have experience fabricating their antennas locally, for example. If antennas can be made locally in South America, shipping costs would significantly reduce as the rest comes in a much easier and smaller space (Sgnome, dongles, etc).
So, if people have tried or even succeeded in making homemade antennas, I would like to know whether it was easy to find the right part and fine-tune the antenna so that they detect the nanotags? Or is it a waste of time to try to pursue this?
Thanks in advance for any insights!
Best wishes
Arne
Arne J. Lesterhuis
SHOREBIRD MONITORING AND CONSERVATION SPECIALIST
WHSRN Executive Office
MANOMET, INC.
I would check with the local Ham Radio community since they would have access to lots of home brew designs. You can make a Yagi with a broom stick and #8 Aluminum clothesline wire. The spacing and element lengths you can get from Dr Google for the 166MHz or 432 MHz tags
Hope this helps
Hi Arne,
I made a 9 element 13dBi antenna with a lenght of 3m but it is tuned to 151.100Mhz (frequency used in Europe).
With the free Mmana-gal software (the one I used to calculate this antenna), it would be very easy to redo the calculation for a frequency of 166Mhz :
All you have to do is take the file from an existing antenna (If you want I can send you my antenna file), enter the new frequency and to click on optimize to obtain the new lengths and the new spacings between heaters for your frequency.
To make the antenna, you need 3m of square aluminum tube (I had voluntarily chosen this length to be able to make 2 antennas in the aluminum bars sold in 6 meters lenght), 8 mm round aluminum tube and small insulating parts to fix the heaters on the square tube…
This antenna uses isolators and it may cause you shipping problems but there are many other antenna versions without isolators :
Just choose, in Mmana-gal, a VHF yagi antenna file, whithout insulators (or draw with the exact lenght and spacing an existing antenna), choose the new frequency (166Mhz) and click on optimize to have all the lenght and spacing of your new antenna…
Mmana-gal gives you the radiation curves, the gain, the front-to-back ratio of your new antenna.
It’s very easy and then just assemble the antenna strictly respecting the lengths and spacing indicated by Mmana-gal
Regards
Bruno (from France)
Thanks, Jum and Bruno, for your input. Very helpful as it seems that there certainly are possibilities. I will check locally with people who can help me finding the right equipment based on your comments and experience.
If you are okay with an omni-directional antenna, this one was made specifically for the 433 Mhz band but can be cut for any specific VHF/UHF frequency. It uses copper wire for the elements. Small machine screws hold the ground elements in place (see insert). It was made using a SO-239 connector. Gain is nothing to write home about, around 3db if ground elements are bent at a 45 degree angle downward so height above average terrain is your friend. Google image search “diy SO-239 ground plane” for more details.
