$10 Antenna Reaches Out FAR!
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- Опубликовано: 1 апр 2022
- Join me in this two-part series as I build (Part 1) and test (Part 2) a 2 meter directional antenna that costs almost nothing!
Original design by Michael Martens, KB9VBR:
www.jpole-antenna.com/2017/02...
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All, I pre-apologize for the horrible jokes...(or maybe I don't)
Love them...
Yogi Beara. I thought the same thing when I first hear of a Yaggi, ha
42 dude, 42.
Thanks for the video.
I had an electronics teacher that would jokingly say, “The bigger the blob, the better the job” 😅
Wow! This is one of the most genius design. So neat. Thanks for the concept.
That's a cleaver idea using small pieces of PVC as a stopper to secure the elements. I hose clamped my elements to the outside of the cross/tee like most others do. 73 de Bill, N6EF.
That's a Great improvment on others I've seen. I'm building it your way. Hope it works as well as it is built.
Keep in mind, you can use the spring that is left over to build flapper valves for a pulse jet engine.
Don't. TEMPT. me!! 73,
I did not need to learn that...
Us Canadians understand Wisconsin weather.... :)
Loving the mods you made here.
Does this use of measuring tape, also work to measure wavelength? Hmmm.....
Thanks !
Great video. Only thing I disagree with is your comment about weather. Weather is weather no matter where you are. I’ve lived in at least 5 states. And even in Oklahoma it can be nice one day and freezing cold (for Oklahoma) the next. Same in Michigan, Colorado, Connecticut. Wisconsin weather is not special to Wisconsin just saying. Again great video. Lol ok ok I do love the advice for soldering on flammable material that made me laugh pretty good
No yelling here, mate hihi. Doing a good job. Thanks and 73's de NL134 (learning for dutch novice license, about equal to technician).
Enjoy - it's a great hobby! 73!
I solder on top of cardboard scraps all the time. It makes for a nice disposable mat. Just don't leave the iron sitting on it!
Absolutely! Although I can hear the safety sallys getting triggered at that from here...
Would it be possible to build something like this for fm reception? Has anyone ever seen anything on RUclips or plans to build a fm tape measure Yagi antenna?
Put an AR pistol brace on it! But then it would become an SBR.... 😢
The real VIP is the Linksys router in the background.
Someday I'll do something cool with it....!!
Only thing I don't think is very intelligent is when a heavy bird lands on at 8 inches and the blade kinks down and stays there !
I'm officially stealing my bosses tape measure. Beat part is its free..... for me! Love the videos. Don't apologize for the humor. It makes the videos more enjoyable. Kd9qlk
Enjoyed! What dimensions would be needed for a 40M Yagi, please?
Big, very big. The driven elements would be approx 33 ft each, spanning 66 ft wide. The reflector would be 5% larger 69'4". The director would be 5% smaller than the driven element at 31'4". However, 40m yagis are typically loaded so you can make it about half this size and the coils make up the difference.
Could you explain the hairpin wire? I thought the elements weren't supposed to be touching each other.😢
Great question - it's because IMPEDANCE acts a little different than RESISTANCE. If the two elements were literally touching, both impedance and resistance between them would be zero. If I add a wire (hairpin) between the elements, resistance will be zero; however, impedance will vary depending on frequency. By choosing a correct length of wire for the frequency of interest (146ish MHz in this case), I could create a situation where the antenna's impedance (roughly 73 ohms) is placed in parallel with the impedance of the hairpin, and works out to a total impedance of 50 ohms.
One of the concepts that has been hardest for me to grasp since I got into ham radio has been the difference between resistance and impedance, so no foul struggling with it!!
Kinda help? 73,
It occurs to me that you did not wind a ballun in the RG-58 coax. I have seen several videos where they drill an entry and exit hole through the 8" PVC length, and wind it around the pipe. Also, you'll need to select your BNC or SMA connector to mate with your HT...but for foxhunting, you will probably want to insert some form of attenuator between the antenna and the HT, so perhaps a BNC would be best. (Also, while I note that you soldered on cardboard or flamable work mat... REAL men would solder right on the dining room table and risk the everlasting wrath of their wife. :) )
All great thoughts. I ended up buying an offset attenuator to go with my antenna. I did discover that cheap HTs are NOT good for fox hunting, but word on the street is Christmas might take care of that problem for me.
Regarding the work mat, that may have been done, and there may be permanent damage on the table to show for it..........
73,
What is the purpose of the hairpin match?
Robert, great question - the coax that runs to the yagi has a nominal 50 ohm impedance. Therefore, any antenna attached to it would work best if its nominal impedance were also 50 ohms. Unfortunately, many antenna designs have different impedances. If you ignore this and just plug the antenna into the coax anyway, your antenna will likely have a high SWR (VSWR if you're a cool kid). This can easily be fixed with any number of different impedance matching transformer designs. Some look like what 'normal' folks would call a transformer - windings on either side of a metal, ferrite or air core - but some don't. Hairpin (aka Beta or shunt) matches are one of those. Other common impedance matching transformers include the gamma and T matches. Hope that helps!
@@hamradioexperience okay... but if you put it on either side of the driven element what is the purpose for the gap? Aren't you effectively closing the circut?
@@rsedaker so that's the weird thing about impedance matching transformers. At low frequencies, you're absolutely right, i.e., if you took an ohmmeter to the driven element, you'd read basically zero ohms, but ohmmeters only measure low-frequency impedance effectively. It turns out that, because the hairpin length is a significant (albeit small) percentage of the 2m wavelength, instead of acting as a short, it acts like a small inductor to cancel the capacitance inherent to the yagi's design!
Digging further into this would be a great topic for a video. It's kind of mind blowing how a wire is a resistor and an inductor at different frequencies. It's not something we normally deal with in everyday life outside of the radio hobby.
Dimenzion ?...help
So, just cut a bunch of pipe at random lengths the make it up as you go, ok. on to the Next video.
@@edwinmcguire6040 thanks for watching! 73,
hair pin match? Trying to rationalize what the purpose of that is? As a total clueless newb it just appears to short out the driven elements? What am I missing?!!
Pistol Grip - great idea, trying to direct a pole while holding as in other builds that have been posted looks awkward as hell - I've even thought it would be worth adding a 1/4-20 UNC nut so you can sit the antenna on a tripod to free your hands up for radio (& beers).
The awkward thing is, at high frequency (like 144MHz), the antenna presents like a ~72 ohm load. It'd be better for the radio if it saw 50 ohms. If I shorted the elements with a ~1/2" or less wire, it would be a short, like you'd expect. Because I used about 5in of wire, It acts like a bit of a load (again, only at high frequencies), bringing the antenna's total impedance to 50ish ohms. Hard concept to grasp! And good thinking on the 1/4-20...shoulda done that. 73,
Hello from 🇧🇷
Do u have a part II for this video? 👀👂
73 de PX7G6946
👍
It's a small world, never expected to find a RUclipsr right in my own backyard with content I'm interested in.
Brian
KD9KYT
73