Here are some photos of a 3 element Yagi ... Boom length = 10 ft / 7.6 DBI / 25 DB FB..
Impedance = 23.8 ohms ---> This means a gamma match can be used to tune the antenna. Check out my Gamma Match page on how to build one .
The Design is done first .......Took about 2 hrs designing this antenna......
I used a DOS software called YA to model all my single band Yagis .... I must tell you all , YA antenna software is really good for designing yagi antennas.... I have used YA many times to do most of the yagi designs, and I have gotten extremely good performance with all the antennas I have built .
To run DOS software on a Windows OS now , use DOSBOX , which is an MSDOS Emulator - http://www.dosbox.com/download.php?main=1
One of the easiest ways to execute the DOS software in DOSBOX , is to create a shortcut on the desktop for DOSBOX ( if it wasnt automatically created ) , then just drag and drop the DOS EXE file onto the DOSBOX shortcut .
I really enjoy adjusting element and spacings ,then seeing the Gain / FB / Pattern / Impedance changing -- the end result ---> Almost perfect antenna.... Check on the "Links to Visit" page to download "YA" .
Here is the antenna already built and SWR is being adjusted.
A good way to adjust a Yagi antenna , is by facing the antenna straight up , so the reflector is parallel to the ground or in this case at an angle.
At the back of the antenna ,is a length of PVC pipe placed there to keep the antenna from spinning.
Photos of the Gamma Match.
AH HA !! Mission Accomplished --- 50 ohm impedance / 0 Reactance on the MFJ-259B SWR Antenna Analyzer .
All Righty Then ! ! ! Antenna at 35ft in the air and working fabulous ... The computer design of now-a-days look different to the older designs.
The smaller spacing is now to the back of the antenna -- resulting in a little higher gain ,better front to back (FB) ........This pic is showing the antenna pointing to the North West ( towards USA ).
This pic is showing the antenna pointing to the North East ( towards Europe )