• You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.

"FAT DIPOLE" centered at 27.385. Questions.

Mudduckmobile

Well-Known Member
Oct 5, 2015
639
339
73
S.W. Washington Coast
First I would like to thank who ever it was that put up the link to K7MEM'(s) site. Thank you!
I have some questions I can't find the answers to.
1. Wire length from the BALUN to the antenna it's self, on K7MEM 's page it does not say?
2. What is the length of the insulators used at the "A" position shown on the drawing?
3. Can I mount this 8 to 10 feet over a ridgeline of a home (3 tab roofing), (two story home) or would it be best to mount at a specific height?
4. Should the wires be oriented as shown on the site page, one on top of the other or would it be best to mount with the wires "flat"?
This looks like a fun antenna to try, and was not clear on these points. I like the though of a "3.63 bandwidth..." at 27.385. I want to feed this antenna with 8x coax as well.
Thank you for your time.
John
 
Last edited:

I do not see a "FAT" dipole on his page. Maybe a link to the page with the antenna you are referring to.
Rich
 
If it was me, I would do:
1. Short as practical;
2. I would use a small Plexiglas, say 4.5 x 4.5 ;
3. I would try it at the height;
4. if you use plexiglas and hang it from the top center it will be up down wire orientation. That's how I would try it first.
It is suppose to be a calculator but it does not work for me, but while calculating a starting point for you it changed.
16'1"
4"
bandwidth 3.63 MHz
upload_2017-4-22_16-53-41.png
 
Last edited:
If it was me, I would do:
1. Short as practical;
2. I would use a small Plexiglas, say 4.5 x 4.5 ;
3. I would try it at the height;
4. if you use plexiglas and hang it from the top center it will be up down wire orientation. That's how I would try it first.
It is suppose to be a calculator but it does not work for me, but while calculating a starting point for you it changed.
16'1"
4"
bandwidth 3.63 MHz
View attachment 20591
Thank you binrat. To make the calculator work (for me) I entered 27.385 in the box and moved my cursor off to the right margin,and hit "enter", and all of the values changed to what was needed at 27.385mhz.
So at the "A" point of the drawing there are 5 insulators, are you saying that they should be about 4.5 x 4.5 in.? Would not 5 ea. of 1in.pve #40 cut at say 2.5 in. be good, as well as use the same pvc for the spreaders (but they are cut to 4in. or 0.13m)?
Oh, and yes. The link is:http://www.k7mem.com/Ant_Fat_Dipole.html
 
Last edited:
Mud.
The reason I said 4.5"x4.5" is "A" is 4" and out of simplicity of keeping the spread for "A" and up down, thats all.
You could trying having the 2 spreaders close to the center lashed together top and bottom with para cord.
 
http://forums.qrz.com/index.php?threads/cage-dipole-vs-single-wire-dipole.360408/

Not the same as the FAT DIPOLE but similar.

The more legs or "wires" on a dipole the more mutual coupling that will occur.
This is seen as broader bandwidth if VSWR is the "only thing considered"
Need to also look at radiation pattern as having more LEGS will skew the pattern of the basic dipole.
This may be helpful or harmful, you may just have to try it and find out.


If you looking for bandwidth, and you do not mind using an antenna coupler "tuner".
Double extended Zepp, antenna,,feed it with ladder line and use the tuner in the shack for a 50 ohm match.
 
I played with a caged dipole years ago. It took a bit but I ended with it covering the 20 Metre band phone portion with ease. It never liked high winds so I took it down.
 
  • Like
Reactions: wavrider
Use a big fat piece of pvc sewer drain pipe. Run one wire down it length and wrap it with aluminum duct tape around the pipe from one end to the other. Make sure duct tape has a firm electrical connection to the bare wire.
It may be a little heavier than a bunch of wires (maybe not...), but it's nice and shiny.
Never made one that fat. Fattest I made was with fence top rail, 1-3/8" diameter.
P2210009_sm-1.jpg

If I recall, each pipe for each side was 8'-5" long.
 
Use a big fat piece of pvc sewer drain pipe. Run one wire down it length and wrap it with aluminum duct tape around the pipe from one end to the other. Make sure duct tape has a firm electrical connection to the bare wire.
It may be a little heavier than a bunch of wires (maybe not...), but it's nice and shiny.
Never made one that fat. Fattest I made was with fence top rail, 1-3/8" diameter.
View attachment 20633
If I recall, each pipe for each side was 8'-5" long.
Thank you.
That sounds like a good one to try. Do you remember how wide your bandwidth was and what your X=, and your R= was and what the swr range was?
 
I made that antenna at a time when I did not own an analyzer. I'll try to find any SWR bandwidth I may have recorded back then.
 
As it turns out, I had only an SWR meter and a 40 channel radio. The tube was 1-1/4" diameter, and the length was 8'-3" per side.

"My swr is 1:2:1 @ channel 40 and 1:0:1 @ channel one."

Had I trimmed off a little more from each end I likely would have seen the SWR curve shift a bit more centered.
That antenna is a 15 minute build with all the parts on hand.
assembly_sm-1.jpg
 
As it turns out, I had only an SWR meter and a 40 channel radio. The tube was 1-1/4" diameter, and the length was 8'-3" per side.

"My swr is 1:2:1 @ channel 40 and 1:0:1 @ channel one."

Had I trimmed off a little more from each end I likely would have seen the SWR curve shift a bit more centered.
That antenna is a 15 minute build with all the parts on hand.View attachment 20634
Its on my list of things to try. It looks like your about 2.5in apart on the shield/center lead for the coax attachment
As it turns out, I had only an SWR meter and a 40 channel radio. The tube was 1-1/4" diameter, and the length was 8'-3" per side.

"My swr is 1:2:1 @ channel 40 and 1:0:1 @ channel one."

Had I trimmed off a little more from each end I likely would have seen the SWR curve shift a bit more centered.
That antenna is a 15 minute build with all the parts on hand.View attachment 20634
As it turns out, I had only an SWR meter and a 40 channel radio. The tube was 1-1/4" diameter, and the length was 8'-3" per side.

"My swr is 1:2:1 @ channel 40 and 1:0:1 @ channel one."

Had I trimmed off a little more from each end I likely would have seen the SWR curve shift a bit more centered.
That antenna is a 15 minute build with all the parts on hand.View attachment 20634
The shield/center feed are about 2.5in. apart at your coax attachment point? And your pipe ends are 2.5in. apart too I am thinking?
 

dxChat
Help Users
  • No one is chatting at the moment.
  • dxBot:
    Tucker442 has left the room.
  • @ BJ radionut:
    LIVE 10:00 AM EST :cool:
  • @ Charles Edwards:
    I'm looking for factory settings 1 through 59 for a AT 5555 n2 or AT500 M2 I only wrote down half the values feel like a idiot I need help will be appreciated