ADS-B Antenna

Posted on May 18, 2014 at 7:53 am

adsb-mapNathan & I built a slim-jim style antenna tuned for 1090 MHz a few weekends ago for ADS-B reception. What is ADS-B you ask? It’s a signal transmitted by a growing number of airplanes containing a variety of information, including the gps position and altitude.
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Dual band (2m/70cm) yagi with duplexer

Posted on April 5, 2014 at 7:35 pm

IMG_20140405_191752The second project of the day was a dual band antenna to try to hit amateur satellites with. This particular one is 2 m & 70 cm. The construction is 1/8″ brass rod with a small duplexer. There are no results to report so far, other than we were able to hit a local 2 m repeater with it. There was one pass of the satellite SO-50 this evening, but we didn’t get anything. We were also in the house and without a good compass, so it doesn’t count. The construction was fairly simple, and some reference sites are listed below. It should have a reasonable amount of gain, and the duplexer should be effective at splitting the signal between the bands, and it should be tuned correctly, but I don’t have the proper tools on hand to test any of that. One of these days I’ll get an oscilloscope, a signal generator, and an SWR meter, and I’ll be much better able to test a lot of these things at that point.

IMG_20140405_191818For today though, it was a fun project, and my first attempt at surface mount soldering. Future plans are to do some more testing in the 2 m and 70 cm bands with other ground based radios at both 1 and 5 watts to try and verify the duplexer is functioning, and an outdoor test to try to hit SO-50 once we’re sure the antenna is working.


Quatrefoil Helical Antenna Project

Posted on April 5, 2014 at 6:49 pm

qfhSay what? A quatrefoil helical antenna is a type of mostly omni-directional antenna that, in this instance has about 3.6 dB gain to the horizon at 137 MHz. Why would you want one? As it turns out, there are 3 NOAA satellites that transmit images in an analog mode called APT as they orbit the Earth. NOAA-15 on 137.620 MHz, NOAA-18 on 137.9125 MHz, and NOAA-19 on 137.100 MHz. Continue reading Quatrefoil Helical Antenna Project…