Build your own HF balun by EA4EOZ
A balun is a MUST for dipoles or similar antennas when they are feed with coaxial cables. Many hams connect the center conductor of the coaxial cable to one side of the dipole, and the shield to the other. Wrong!
http://ea4eoz.blogspot.it/2012/09/build-your-own-hf-balun.html

Coax Choke Balun Designs by G8ODE
The two coaxial Choke BALUNS are constructed from 40mm plastic drain pipe using 8-10 turns of Mil Spec RG58 or MIN-8 Coax (approx 2metres) The bottom end coax is held in place with a small plastic tie-wrap. A plastic cap from a food jar is used as at the top of the BALUN.
https://rsars.files.wordpress.com/2013/01/choke-balun-designs-g8ode-iss-1-31.pdf

Dual Ratio 1:1 & 4:1 Balun for 3.5 – 30.0 MHz by DB6NT
This balun has been used at 100watts with a full-sized G5RV, Windom and 40m & 20m vertical antennas. It is essential that the Amidon™ toroid is housed in a watertight box, such as an IP56 Rated box.
https://rsars.files.wordpress.com/2013/01/dual-ratio-1-1-4-1-balun-for-3-5-30-0-mhz-1-31.pdf

End Fed Half Wave Antenna Coupler (EFHW) by MØUKD
I have been experimenting with feeding end fed half wave antennas matched by a parallel tuned circuit coupler. This article will explain my findings and reasons for constructing it the way I did.
http://m0ukd.com/homebrew/baluns-and-ununs/end-fed-half-wave-antenna-tuned-coupler-efhw/

HF 1:4 balun by PA3HCM
The first HF antenna I wanted to build was a Windom Antenna. This antenna required a 1:4 balun, so I made one.
http://www.pa3hcm.nl/?p=305#more-305

Homemade HF Antenna Balun by AA5TB
A balun is a device that is used at the feedpoint of a balanced antenna when an unbalanced feedline is desired to feed the antenna. Balun is a contraction for BALanced to UNbalanced.
http://www.aa5tb.com/balun.html

QRP Balun by AA5TB
I had a high permeability ferrite rod and an old B&W dipole center insulator in my junk box so I decided to construct a choke type balun for QRP use.
http://www.aa5tb.com/qrp_balun.html

Windom baluns for kilowatt range by OH7SV
Windom balun made with Amidon ferrite toroids.
Windom balun made with surplus ferrite rods.
http://www.jumaradio.com/windom/windom-balun.html

Enhanced OCF Dipole Balun by OH7SV
All antennas need a common mode balun. Especially OCF dipole (sometimes called Windom) needs enough common mode reactance because the feeding point is "hot" - not in the zero RF. Here is an enhanced balun for OCF dipole.
http://www.jumaradio.com/enhanced-OCF-balun/enhanced-OCF-balun.html