3 Element 50MHz Long Yagi by ON6MU
VHF Optimized Yagi Antenna for the 6-meterband (50 Mhz) RE-A50Y3.
http://users.belgacom.net/hamradio/schemas/50mhz3el_yagi.htm
 

4 and 2 Element Quad Antennas for the 6m Band by G4AON
This antenna is based on a design for a portable 2 element 6m Quad by VE7CA, which is featured in the 19th Edition of the ARRL Antenna Handbook. While the basic 2 element design was OK, I felt it worth trying 4 elements.
https://www.qsl.net/g4aon/quad/

4 Element Yagi for 6 meters by IW3EDI
 
http://www.iw5edi.com/ham-radio/4557/4-element-yagi-for-6-meters
 

50MHz 50Ω dipole antenna by JA1HWO

http://mk1502.web.fc2.com/ahv6/50dp.htm

50MHz High Gain Antenna by ZS2FM
An efficient antenna system is a prerequisite for more successful six metre operation. Most amateurs start off with a four element yagi, which is more than suitable for F2 propagation when signals are very strong.
http://www.qsl.net/zr6dxb/PROJECTS/ZS2FM/zs2fmantamp.htm

50MHz Moxon Rectangle by N3OX
The FT-857 is the first radio that I've owned with 6m capability, and so I needed a 50MHz antenna. The HF wire works in a pinch, but what I really wanted was a beam.
http://www.n3ox.net/projects/sixmoxon/

6 Meter 5/8 EDZ Signal Squirter by N4UJW
The Six Meter Extended Double Zepp is a very easy and inexpensive antenna for the 6 meter buff to build in about an hour or less and will add about 3 db to your signal from it's broadside bi-directional pattern when installed about a half wave up from the ground.
http://www.hamuniverse.com/6meteredz.html

6m 2EL cubical quad antenna by JA1HWO

http://mk1502.web.fc2.com/ahv6/6mcq.htm

6m/2m/70cm Yagi Antenna Built from Old TV Antenna by KGØZZ
This turned out to be a great little antenna. It works the 6 meter, 2 meter and 70 centimeter bands. You can use one common feedpoint or two seperate feedpoints depending on how you would like to connect this antenna to your transceiver.
http://www.amateurradio.bz/tri-band_yagi.html

A four element antenna for the 50 MHz Amateur Radio Band by DF9CY
After working three years with a homemade DL6WU type 6-element-antenna, I was intended to build something new as the old antenna decided to fall apart. So I came to this one. After some calculations I came to a 4 element yagi.
http://www.df9cy.de/tech-mat/fourfour.htm

A portable three element 6M yagi for less than twenty pounds! by PA3HBB/GØBZF
Having just got myself a new Alinco DX-70 at Friedrichshafen, I required a simple beam antenna for the coming summer. So I looked at the criteria I needed...
http://www.qsl.net/pa3hbb/6m3e1.htm

A Six element antenna for the 50 MHz Amateur Radio Band / Version 4 by DF9CY
I have mounted the 6 Element antenna about 2 meters above my 3 element antenna for 28 MHz. (The 28 MHz antenna is a well performing "EZNEC redesigned" CB radio antenna)
http://www.df9cy.de/tech-mat/cy6ele50.htm

An alternative to the M2 6M7JHV antenna for 6m by G3WOS
The M2 6M7JHV is a 7-element high performance antenna that is used by many 6m (50MHz) DXers around the world for terrestrial and EME QSOs.
http://www.gare.co.uk/6m_antenna/

Antenne 3 éléments pour le 50 Mhz de F6FEO
Il s'agit de remplacer mon ancienne Jungle Job, par un modèle ayant plus de gain, sans présenter trop de prise au vent. Mon choix s'est porté sur une beam 3 éléments décrite sur le site de DK7ZB.
http://f6feo.homebuilder.free.fr/aerien_50Mhz.html

Construction Details for 50MHz-Yagis in DK7ZB-Design
The 50MHz-Yagis are designed with an impedance of 12.5Ohm or 28Ohm. The 12.5-Ohm-Yagis are designed with small bandwidth (300KHz) at highest possible gain and must be mounted in a clear surrounding.
http://www.qsl.net/dk7zb/6m/details.htm

LC Match Dipole for 50 MHz by JA1HWO
Since the impedance of the dipole antenna is about 73Ω, if a commonly used 50Ω coaxial cable is used, the SWR will be close to 1.5, causing a mismatch.
http://mk1502.web.fc2.com/ahv6/6mdp_lc.htm

Moxon antenna for 50MHz by OH1TV
This antenna was designed for a local OT-network where radios are always on. Station distances are 10...100 km.
http://www.kolumbus.fi/pekka.ketonen/Moxon%20antenna%20for%2050MHz.pdf

Portable antenna for 6m by OH1TV
This is a mechanically improved version of 6m 3-el yagi made for our VK9XM operation.
http://www.kolumbus.fi/pekka.ketonen/6m%20portable%20yagi.pdf

VHF/UHF X-Beam by KØEMT
I sat down and drew out what I did and thought I'd pass on what I did/found out. The design is from The 1993 ARRL handbook that was given to me by wd0hbx. The x-beam was originally intended as an HF mono-band beam. I used the formulas to build it for 6m. It also happens to work out really well for 2m & 70cm use as well.
http://www.delboyonline.co.uk/m0dad/Homebrew/vk2abq_beam_50_mhz.htm

ZX 6-7 Yagi Antenna for 50 MHz by DF9CY
With a little additional material you are able to extend the ZX-Yagi 6 Elements for 50 MHz by about 2 meters. The gain rises about 0,8 dB.
http://www.df9cy.de/tech-mat/zx-6-7_cy/zx6-7.htm