Twin X-Mount Dipole Idea

[KC9Q]

LY,

Cable TV uses RG-6/U or RG-7, aluminum shielded cable with solid copper center conductor. These require the F-Series of crimp-on connectors. What you need for Two-Way operation is RG-59/U (same diameter as RG-8X), or RG-11/U (same diameter as RG/213/U) cable. Both of these have copper braid and either solid or stranded copper center conductor. The 1/4 wave matching section for the Turnstile Antenna is [246/F(MHz)] x Velocity Factor. The Velocity Factor (VF) varies from manufacturer to manufacturer, and can be anywhere from 66% (.66) to 82% (.82), which is a factor of the dielectric material between the center conductor and the shield.

The classic Turnstile (crossed dipoles) provides omnidirectional coverage with horizontal polarization. Since it is basically two dipoles (phased together) it will still yield 0 dBd of gain (about 2.15 dBi).

73,
Mike

 

[Lil'Yeshua]

LY,

Cable TV uses RG-6/U or RG-7, aluminum shielded cable with solid copper center conductor. These require the F-Series of crimp-on connectors. What you need for Two-Way operation is RG-59/U (same diameter as RG-8X), or RG-11/U (same diameter as RG/213/U) cable. Both of these have copper braid and either solid or stranded copper center conductor. The 1/4 wave matching section for the Turnstile Antenna is [246/F(MHz)] x Velocity Factor. The Velocity Factor (VF) varies from manufacturer to manufacturer, and can be anywhere from 66% (.66) to 82% (.82), which is a factor of the dielectric material between the center conductor and the shield.

The classic Turnstile (crossed dipoles) provides omnidirectional coverage with horizontal polarization. Since it is basically two dipoles (phased together) it will still yield 0 dBd of gain (about 2.15 dBi).

73,
Mike

Thanks.
I plan on running two rg59's from each dipole to a T-junction. 50 ohm feedline wiil make tge trip to the transceiver from there. One leg will be 1/4 wave longer in order to make this antenna work. The aspect of making a set if beams sounds enticing. The pic is on this link. >Circular-Polarized CB Beam Antenna Plans

 

[HomerBB]

Been thinking about a circular polarized antenna for a while. Just not got around to it. Especially a two element setup. It would seem to me to be a very easy and quick antenna to put together if it was not intended to look very pretty for resale.

The only challenge I see for using SS whips is that there would be some asymmetrical shaping of the X or + due to gravity pulling the ends of the whips downward when mounted on the vertical plane. I was thinking of using tubing.

Git ur dun.

 

[Lil'Yeshua]

Been thinking about a circular polarized antenna for a while. Just not got around to it. Especially a two element setup. It would seem to me to be a very easy and quick antenna to put together if it was not intended to look very pretty for resale.

The only challenge I see for using SS whips is that there would be some asymmetrical shaping of the X or + due to gravity pulling the ends of the whips downward when mounted on the vertical plane. I was thinking of using tubing.

Git ur dun.

Agreed. I'd love to make it out of tube aluminum but I need to learn how to make antennas out of that stuff first. I'm looking at ARRL's store on antennas. Maybe I'll buy one of their books. Any suggestions?
http://www.arrl.org/shop/ARRL-Antenna-Book-22nd-Edition/
http://www.arrl.org/shop/Basic-Antennas/
http://www.dxengineering.com/
P.S. two MFJ-347's and four 102" SS whips makes for an easy antenna to make though
Using SS whips can get expensive especially if I'm wanting to make a set if beams using two or more if these twin dipoles.

 

[HomerBB]

I suppose all of them are good books.
There is a lot of info available right here so that if it is experimenting you want to do, or simple building, the $ for the books might sooner be spent on the materials.

I tend to find any books from respected sources like ARRL and AntennaX to be expensive beyond their necessity. Also, newer editions of some of the publications have very little useful material in them beyond what is available in the used market, so I tend to look in other places for what I find.

I have no personal recommendations for you. Others may. Seem odd? Too much available that can be downloaded, and too many respected members of good forums like this one will answer questions. I just don't buy $100 dollar books to answer 50¢ questions.

 

[Lil'Yeshua]

I suppose all of them are good books.
There is a lot of info available right here so that if it is experimenting you want to do, or simple building, the $ for the books might sooner be spent on the materials.

I tend to find any books from respected sources like ARRL and AntennaX to be expensive beyond their necessity. Also, newer editions of some of the publications have very little useful material in them beyond what is available in the used market, so I tend to look in other places for what I find.

I have no personal recommendations for you. Others may. Seem odd? Too much available that can be downloaded, and too many respected members of good forums like this one will answer questions. I just don't buy $100 dollar books to answer 50¢ questions.

Well,actually,I was wanting to buy this book>


Circular-Polarized CB Beam Antenna Plans
Does anyone know about this guy?
The ARRL antenna books looks like something meaty to sink my teeth in. An investment? Yes.

 

[HomerBB]

The ARRL antenna books looks like something meaty to sink my teeth in. An investment? Yes.

It is a good publication. I only meant to say the info is less expensive and as accurate from other sources . My recommendation is to look around. I got my copy free from a friend.

 

[Lil'Yeshua]

It is a good publication. I only meant to say the info is less expensive and as accurate from other sources . My recommendation is to look around. I got my copy free from a friend.

Will it help me make a CP antenna array including how to wire it up? I have been looking on the web. Any recommendations as to where to look?

 

[HomerBB]

Here is one version of the harness:

 

[Lil'Yeshua]

Here is one version of the harness:

Cool! I have a T-connector ordered.
Where would you buy your RG59 coax at?
I'm guessing that VF needs to be factored in as well

 

[Lil'Yeshua]

Mouser Electronics - Electronic Components Distributor

 

[Lil'Yeshua]

At a 1/4 wave the coax from the antennas to the feed line would have to extend done the mast pole. I wonder if both antenna feed lines can be coiled in rf choke times two. ??????
http://www.worldwidedx.com/attachme...dipole-idea-circular-polarization-harness.pdf op:

 

[Lil'Yeshua]

http://www.worldwidedx.com/attachme...dipole-idea-circular-polarization-harness.pdf
http://www.worldwidedx.com/amateur-radio-antennas/28715-best-coax.html

 

[Lil'Yeshua]

Found a 9' RG 59/U co-phased harness with PL-259 connectors on Amazon. This would eliminate the T-connector. Just use one SO-239 barrel connector and a 1/4 wave 50 ohm jumper to one dipole.

 

[wavrider]

You can use 3/4 wl .75 for phasing it will work the same as the 1/4 wl as far as impedance matching but it will be a longer distance so you will have more length of coax to be bale to position the antenna where you want it.

Found a 9' RG 59/U co-phased harness with PL-259 connectors on Amazon. This would eliminate the T-connector. Just use one SO-239 barrel connector and a 1/4 wave 50 ohm jumper to one dipole.