The Yagi-Uda Antenna - Lesson 3

This video lesson introduces the Yagi-Uda antenna, which consists of a single driven dipole antenna operated within an array of other non-driven, linear elements known as “reflectors” and “directors.” The function of the reflectors and directors is to help focus the typically rotationally symmetric radiation of a dipole antenna in a single direction. Yagi-Uda antennas are narrowband but offer very high directivity with linear polarization. This course was created for Ansys Innovation Courses by Dr. Kathryn Leigh Smith, assistant professor, UNC-Charlotte, in partnership with Ansys.
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[@lerneninverschiedenenforme7513]

Highly underrated material! Thank you very much for the work!

[@emviso]

Thank you!

[@waylonk2453]

Thanks for posting this on KZbin. The visuals are the best I've seen so far when learning about this antenna design.

[@deadly_komodo]

Thank you for visualizing it like that. Very helpful.

[@JulietNovember9]

Great explanation. It was voodoo to me before!

[@johngranato2673]

Great explanation, young lady. Thanks a Million!

[@glenmartin2437]

Thanks. That was a pithy, concise review. Keep the videos coming.

[@kcoRwobniaR]

Thanks ! Great material to begin with.

[@emviso]

Thank you for the feedback!

[@CaseyStanton]

This is so easy to understand. Great job!

[@emviso]

Thank you!

[@Javierriveraab]

Thank you very much for the explanation , professor!!

[@user-eg7ce7wn8f]

Great video, much appreciated.

[@jluke6861]

Thank you for the Great Video.

[@nwadeswim]

Thanks so much! This material is fantastic!

[@georgebreckenridge3351]

Great job! Thanks

[@stevenjenks9789]

Very good presentation 😊

[@shaggyasir]

great vid !

[@RP4886]

Great video. Thank you

[@wesKEVQJ]

Thank you for the very informative video.

[@tomstrum6259]

Thx for the video...What Causes the Inductive Reactive element (the Longest element) to Reflect rf energy back towards the Driven Dipole element ? Also, what causes the Capacitive Reactive (cascading Shortest) elements to steer rf energy Foward away From the Driven Dipole element ?? Why are Parasitic Elements specifically 5% Different in Length and Why are Parasitic element Spacings usually Near a 1/4 wavelength Boom Spacing ? How were long multi element Yagis designed Before computer models ? Thx.....

[@azizulhakimbappy3253]

Thank you

[@jayjay-gl4fj]

Good video!!

[@yuta.7319]

日本にはもっと素晴らしい発明がたくさん有る🇯🇵万歳

[@jeffreycanipe1936]

I just found this author and i really enjoy the lessons. Being a ham radio operator, i am very interested in building a 70 cm (approx: 443 MHz) yagi. Thank you.

[@ahmedmoustafa6829]

Thx

[@lawrencecohen1619]

Excellent description and visuals of the Yagi antenna.

[@emviso]

Thank you!

[@idonthaveaname42]

really cool

[@erkintek]

Directors should connected with each other?

[@examplerkey]

Best!

[@keithmarkcam6216]

Thanks for the information

[@emviso]

Thank you for the comment!

[@jhonphil1237]

best explanation

[@emviso]

Thank you!

[@trainmaster0217]

I never can get a reflector to work with the antenna I have built....no matter the spacing. The signal level always drops with a reflector.

[@sidb6471]

thank you so much

[@emviso]

You're very welcome! =)

[@soaperino]

@@emviso thank you!

[@emviso]

@@soaperino Thank you!

[@compuguy123]

What if you have a vertical and horizontal element 90 degrees from each other?

[@JaraFPV]

What will happen if the reflector and directors are not aligned in the center? Say the directors are all aligned at the bottom instead of them having on the center of the reflector?

[@emviso]

Simulate it and find out! www.ansys.com/academic/students

[@usamamumtaz1378]

Good

[@soaperino]

yes

[@RuVi78]

what happen when yagi has a reflector - driven and no director?

[@TyWooly42]

Great information. Too bad you don't have a better microphone.

[@anupammathur17]

Shouldn't a yagi have a folded dipole as driven antenna for the purpose of higher directivity and gain?

[@Doonit_hard_way_since_65]

Folded dipole is used because of it's higher characteristic impedance (2-300ohm). The parasitic elements have an effect of dropping the driven element feed impedance. a straight dipole's characteristic 75 ohm impedance would fall into the single digits without some form of matching. We can get around 50 ohms with a folded dipole without needing a gama match, or some other form of matched feed point alteration.

[@anupammathur17]

@@Doonit_hard_way_since_65 Thanks👍

[@timetraveler7]

What should the length of the antenna be? Does it need to be half wave dipole or can it be short dipole?

[@emviso]

The driven antenna is typically a half-wave dipole.

[@timetraveler7]

@@emviso would having a yagi antenna with a short dipole increase gain?

[@Doonit_hard_way_since_65]

@@emviso a 1/2 wave dipole will drop to around 20-ish ohms as a result of the proximity of the parasitic elements. You are going to need some form of matching, or you are going to see inefficiency, and in the case of a typical transmitting antenna... magic smoke getting out of the finals.

[@FFdo.]

depends on what are your needs you can try with a 1/4 wave length as well if you are working lower bands like 1.6, 3.5 or 7Mhz. for 7M/40m a 10m driven element will work fine with one reflector and one director.

[@itrstt66]

it seems liek the director has a parasitic refletcion effect, is it right?