2 Meter Yagi Antenna w/ Gamma Match (Part 1/2)

[coleco1982]

Excellent Work Dave! I really enjoyed watching both of these videos. I am planning to build a yagi to work the LEO Satellites and I had no idea how to make a gamma match! Thanks to you, I now know exactly how. Thanks again and 73 DE KB3TUO

[Shufei]

Again, this is seriously good stuff, great for those of us who want to build antennas on principle, but are none too sure of our crafting skills. I like that you cover it all in detail, not skipping out any little details on the assumption that people simply know things about antenna construction. Seeing you build helped clear up alot of little nagging questions I had about making antennas. I think I'll go get to my 2 m project tout de suite!

[matthewz07]

i made one exactly as you instructed and let me tell you this sir......

YOU ARE AWESOME !!!!! thank you so much !!!!! im here in the phillipines and vhf is so popular here ,, ive been using a diamond antenna for the last 5 years,, but yours is working great...

[zerozedzed]

@matthewz07 Thank you! I am very pleased to receive such a great compliment. You are the first one for me to hear back from that has built this antenna. :)

[matthewz07]

@zerozedzed im currently using this and i had no problems whatsoever ,, made some modifications and even made another one which i did as an array .. as we call it .. dont really know what to call it but friends of mine had ask me to build one for them.. i also directed them to your video... thank you so much sir and hope you keep on making those excellent instructional video... YOU ROCK SIR ... !!!! 10- 73's from the phillipines!!

[zerozedzed]

@matthewz07 That's great! :) I am glad to hear that you are experimenting and have made some modifications. The basic point of the video really is to demonstrate how to make the gamma match. You can use the gamma match with other yagi designs. And yes, "array" or "phased array" is correct. 73 :)

[MAJESTIC10110]

Nice video. For those metric boys Free space wave length formula is 300/144.250 = Full wave length in meters = 2.08m divide by 2 for 1/2 wave in meters (144.250 can be replaced by any frequency). You can reduce antennas 5% from the freespace value. 300 represents 300x10^6 m s-1 (speed of light) and since the frequency is in Mhz (10^6 Hz) we can just enter 300/Mhz for our full wavelength.

Have fun!

2E0OLI

[zerozedzed]

The coax cable length mentioned in the video for testing the gamma match should instead be multiples of a 1/2 wave length. For 144.250 the formula for a 1/2 free space wave length is (984 / 144.250 = 6.8215' ) / 2 = 3.41075' (or about 3' 4-15/16"). If you use multiples of 3' 5" you should be close for use on 2 meter sideband.

[dbindner]

@zerozedzed You say "for testing the gamma match" in your comment. Do you mean to say, that the length of cable is most important just for testing? Or do you really mean to imply that this antenna system will run best in general with an appropriate length cable (i.e. a multiple of 1/2 the wavelength)?

[zerozedzed]

@dbindner SWR readings will vary with the length of cable and with height. For a more accurate SWR reading you may use 1/2 wavelengths of cable but this is not a must for the antenna to work. Using 1/2 wavelengths allow you to adjust the antenna rather than the coax cable. I built the antenna in December and checked the SWRs indoors in the basement, about 5 feet underground, and still saw the lowest minimum SWR being at the desired operating frequency.