| Electronics > Projects, Designs, and Technical Stuff |
| Radio Direction Finding |
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| PA3BNX:
Hello EveryBody, Today I did again some work on the new plate antenna. It works I think but the switcher needs + and - volt control signals so it needs something like a max232 that has a feed of only +5 volt and generates rs232 + and - voltage signals. I think I am going to build a small PCB with the max232 that can be connected between a standard 4017 SuperSimpleSoundDoppler generator. The circuit of the 4017 in the file above Rommeltje2.png does not work because you need + and - control signals. Today 27-05-2013 Replaced Rommetje2.png in Rommeltje3.png with max232 Today 04-06-2013 Replaced Rommeltje3 with Rommeltje4.png My antenna plate is now 22 by 22 cm and hight above groundplate about 5 cm I get an SWR of about 1.6 at 2 meters it looks the antenne is directional and switchable I dit create the 2 control signals 15 and 20 with my + and - 5 volt supply and two tumblers to test al configuration with the switcher. Take look at these patents: US3202995.pdf US4510498.pdf US4635065.pdf Antenna could be called a traveling wave antenna or even looks like a beverage antenna. |
| PA3BNX:
Hello Every Body, Here a is picture of the Traveling Plate Direction find antenna prototype. |
| SeanB:
There are a lot of those adorning police cars here, as a part of the Tracker system. Of course, at the moment the police are on strike over pay, watched the demo today at lunch time as I drove past. |
| PA3BNX:
Hello EveryBody, I just did do some drawing of the driver for the plate antenna. Just a 4060 and a lm358 No voltage regulation needed I think The opamps should switch between + and - So I should build this one on breadboard to see if it's working ! Whoops replaced the drawing because the - inputs off the lm358 has to be on 1/2 positive tension to let them switch between + and - voltage Now it should work..... Here a nice link about the Wullenweber HF direction finding http://www.navy-radio.com/frd10.htm |
| PA3BNX:
Hello EveryBody, Today I finally got the rs232 max232 running on Matrix board. I had ta place two pulldown resistors in of 4k7 at input of the rs232 driver after the 1n4148 diodes Finally I could test the new antenna and it worked strange. I found that the fast control signal must be connected to the center antenna plate control (connect no 15) I did replace the drawing in Rommeltje4.png some messages above. So first the sequence was antenna 1 3 2 4 and now it is 1 2 3 4 Tomorrow I do some more test with the antenna. On my FT817 in AM mode on 2 meters and with a small fox transmitter. It looks it works all all right even indoors. |
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