Yagi antennas for under $5

[mkewman]

holy hell! i'm going to have to try to make one now!

awesome!

 

[ocscan]

With regards to the diameter of the various elements is bigger better? Also what are the advantages of hollow versus solid tubing. This is for indoor usage so strength isn't really and issue.

 

[kc8syo]

Have you built any 800mhz antennas and if so are they for sale. Interested buyer. TIA

 

[spiritwolfpr]

Hello Friends:

Hey!! I'll like one of thouse uhf i'll pay for it!!!

 

[N4JNW]

Yo man... hook up a fellow ham! I'd like a 2M yagi... the duckie don't cut it for repeater work around here...

Shoot me a price on what you'd take to build me a 2M!

 

[gcgrotz]

QST had an article in their annual antenna issue last month or 2 about building yagis. It had a real neat scheme for drilling the holes perfectly straight using another piece taped to the boom to mark a line down it and then rotating it to mark another line for the other side. Looked pretty good.

The idea about the clips is a great one too.

 

[n8myc]

KF4LNE Dan. Thanks a million for the neasurements. I built one yesterday and WOW! It cleaned up a lot of noise for some of my local 450 and 460mhz users and I can now hear stuff I couldn't hear before. It cost less than $1.00. I had everything but the dowel and it took less than one hour.
Bob N8MYC

 

[ocscan]

I'm happy to report that a wooden hockey stick work as well as dowels and are easier to drill. Built mine for less than 1 Canadian dollar...Works great.

 

[Alain]

I may also see if I can build a VHF antenna for 152MHz for under $5 and post the results here too. I have one for WX band that is made from PVC pipe and sluminum rod from Lowes, but its overall cost was nearly $20 and its only estimated to be 7db. If I can find metal rod cheap enough I think I can do a $10 Yagi for VHF

Hi Dan,

Great antenna! Thanks so much for the post. It's guys like you that make this the best scanner site on the web.

I would be v-e-r-y interested in the how-to's of this 152 MHz VHF antenna. Most of our California Department of Forestry freq's are within a few megs of 152 [either way]. My discone works well enough, but I'm always eager to tinker, tweak and squeeze for every last possible db...

Merci encore!

Alain

 

[dave3825]

Dan When drilling the holes in the dowel,,
I see the driver holes dont go all the way thru because they are 2 elements but the rest of the elements -- are they done the same as the driver or do those holes go all the way thu and use one long element????

 

[ROY_PICKETT]

I have about 15 --5' pieces of steel rods ,, would that work for the elements..They are about 3/16" in diameter .. And would PVC pipe work for the boom? Thanks Roy

Well i guess PVC pipe wouldn't work because it has to be metal.. Now i feel a little weird..

 

[gcgrotz]

I have about 15 --5' pieces of steel rods ,, would that work for the elements..They are about 3/16" in diameter .. And would PVC pipe work for the boom? Thanks Roy

Well i guess PVC pipe wouldn't work because it has to be metal.. Now i feel a little weird..

The rods would work great but watch for rust if they aren't stainless, and the weight should be considered too.

Yagis can be built on an insulated boom, I don't know the specifics but it probably changes the ideal element spacing a bit. I once built a Quagi on a wood boom and it worked great. It uses a loop reflecter and driven element and straight directors. It was in an ARRL publication years ago.

 

[Alain]

A High Gain Yagi-Uda with a different twist...

Hello All,

Recently, I've done some research and found a book with a very similar yagi...

I bought W. Clem Small's book, "The Antenna Handbook" from Grove some years ago. On page 51 is the "High Gain Yagi-Uda" that he built. It has one very unique feature: the reflector, driven element and all the directors are held in place with monofilament line...yes, fishing line! No holes to drill in a dowel or PVC pipe! The author used 30 pound test.

This feature permits you to hang the thing between two branches in a tree, between a clothesline and the house; you can hang the antenna between any two points. Using fishing line makes the yagi totally portable; you can just roll it up like a sleeping bag and take it wherever you want. You could place it in a mailing tube if you are concerned about bending it.

When I make mine, the only thing I'm gonna change is the "feedline" attachment. Instead of soldering the coax to the driven element, I going to use a Budwig Hye-Que. This way, I can directly connect the PL-259 coax connector to the SO-239 that is on the Budwig...

Alain

 

[dirtfinder]

http://www.dxzone.com/cgi-bin/dir/jump2.cgi?ID=11183 Here is a pretty good site that I used to build a yagi tune to 868 mhz. The antenna that I made is picking more up inside the house than the wilson yagi 40 feet up outside.

 

[wildbillx]

Need a Yagi

If anyone is willing to make one, I will pay. I am at college and dont have any tools but really need a good antenna to recieve 856-860mhz. You can email at wildbillx@yahoo or PM on RR. Thanks

 

[dave3825]

Dan When drilling the holes in the dowel,,
I see the driver holes don't go all the way thru because they are 2 elements but the rest of the elements -- are they done the same as the driver or do those holes go all the way Thru and use one long element????

Anyone ? ? ?

And I cant get the coax to solder the shielding is aluminum

Whats the work around for this???

 

[MMIC]

....digressing for a minute from the ongoing conversation.....

I need to commend your ingenuity in getting the materials you need and putting them together into an effective antenna for you. Isn't the radio hobby great?

 

[jonny290]

Correct.

To 'kick this up a notch' as it were, I'd suggest going to Lowe's and buying 1/8" brass rod for the elements, and a chuck of 7/8" or 1" PVC pipe. It should still cost you less than five bucks.

Also note that buying brass rod, along with a bunch of chassis mount BNC or UHF connectors, will allow you to make ground plane 1/4 wave or vertical dipole antennas all day long. Just get a nut and bolt to clamp the ground elements to the connector, solder the other element straight to the center pin.

antenna projects are way fun

 

[Alain]

QST had an article in their annual antenna issue last month or 2 about building yagis. It had a real neat scheme for drilling the holes perfectly straight using another piece taped to the boom to mark a line down it and then rotating it to mark another line for the other side. Looked pretty good.

Hey All,

Here is the article that is referred to above:

http://www.arrl.org/qst/2006/11/archive-october.html

Alain

 

[jonny290]

What is the purpose of a gamma match and can you break down its constuction a little more...will be constructing an 800mhz model this weekend.

yagi antennas have dead-low feed impedances, like 5-20 ohms depending on number and spacing of elements. The gamma match feeds the antenna at the center and 'another point' which is determined by the shorting strap. Impedance values change as you go down an antenna element, so you find the spot at which you get a perfect 50 or 75 ohm match at your design frequency.

A 3-5 element yagi should have a feed impedance of 10-20 ohms, i would suggest using a 300-75 TV balun but wiring it *backwards*. Put an F connector on the antenna feed, plug the balun into it, strip your coax back 1/4 inch and hook either side to a screw. Voila, instant transform from 10-20 ohms up to 40-80, much happier.


Also note that you can transform a 15 ohm impedance to a 75 ohm impedance by use of a 33.3 ohm quarter wave stub, which we can get close to. We can easily make a 37.5 ohm transmission line from two quarter-wavelength runs of 75 ohm coax paralleled (centers connected at both ends, shields connected at both ends). Connect one end to the antenna feed, the other end to your 75 ohm feed coax and trim it for best SWR or reception. Be sure you multiply your quarter wave calculation by the 'velocity factor' of the coax (you can look this up on Google), and trim to that value.