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Maxgain
Junior Member
Username: Maxgain
Post Number: 18
Registered: 3-2007
| | Posted on Friday, April 13, 2007 - 2:40 pm: | 
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1. If you remove the radials from the Maco 5/8 groundplane will it's performance be similar to the Imax-2000?
2. Why does the Maco 5/8 need radials and the Imax not when they are both 5/8 wave? |
Tech237
Moderator
Username: Tech237
Post Number: 744
Registered: 4-2004
| | Posted on Saturday, April 14, 2007 - 9:05 am: |
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Firstly any 5/8 antenna needs some form of groundplane system be it radials, a flat metal plate or whatever, so removing the radial from the Maco will not improve its performace. More than likely it would degrade it.
Are you sure the IMax is a 5/8 and not a 1/2 wave antenna?
Simon
Tech237
KD7IEB
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852
Intermediate Member
Username: 852
Post Number: 289
Registered: 3-2006
| | Posted on Saturday, April 14, 2007 - 10:17 am: |
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Actually isn't the Imax a .64 wave antenna.
Tommy~852~CEF 750
Do They Make Anything Besides "GALAXY"?
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Maxgain
Junior Member
Username: Maxgain
Post Number: 21
Registered: 3-2007
| | Posted on Saturday, April 14, 2007 - 11:04 am: |
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The Imax 2000 measures about 23 ft long , that puts it up there with a 5/8 wave.
Unless the Imax 2000 is a hoax and IS only a half wave.
????? |
Tech808
Moderator
Username: Tech808
Post Number: 13485
Registered: 8-2002
| | Posted on Saturday, April 14, 2007 - 11:12 am: |
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Actually the IMAX 2000 has a .64 wavelength element, as Tech833 stated in his Review/Article.
Read Tech833's Review/Article below and it should answer all of the questions anyone may have on the IMAX 2000 in the area below.
Subscriber (Preview)
» Product Reviews
» Imax 2000 Exposed Base Antenna
» Review
Lon ~ Tech808 ~ N9CEF
CEF#808 ~ CEF HAM#33 ~ CVC#002
10-10 #61493 ~ 10-10 VP#2688
Tech808@copperelectronics.com
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Maxgain
Junior Member
Username: Maxgain
Post Number: 22
Registered: 3-2007
| | Posted on Saturday, April 14, 2007 - 3:48 pm: |
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But why does the Maco 5/8 need radials to work and the Imax 2000 not?
I think that the 5/8 vs .64 difference in negligable, they are esentially the same wavelength.
I have read the 'Imax 2000 exposed' some time ago and it does not explain at all why the desighn does not need radials.
Further comments? |
Marconi
Advanced Member
Username: Marconi
Post Number: 695
Registered: 11-2001
| | Posted on Saturday, April 14, 2007 - 7:01 pm: |
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Maxgain, I don't know either why they work without a ground plane, but they do. I'm like you, I don't think it makes much difference either way, .64 or .625.
What I would like to know is how did 833 determine the wavelength of the Imax 2000 antennas as to being .64 wavelength if, as he states, it is 270.5" long? Maybe my math is wrong, but this is what I get.
36' x 12" x .64 = 276.48"
36' x 12" x .625 = 270"
So, what is it? |
852
Intermediate Member
Username: 852
Post Number: 290
Registered: 3-2006
| | Posted on Saturday, April 14, 2007 - 9:31 pm: |
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To quote from Tech 833's article on Imax 2000 exposed.
"The first thing you notice about the Imax 2000 is that it is LONG! I measured the copper wire elements after they were removed from their fiberglass radomes:
Bottom section: 80 inches
Middle section: 94 inches
Top section: 96.5 inches
That makes the total radiating element length 270.5 inches. Using 27 MHz. (CB) as center frequency (which this antenna was designed for), that makes the Imax 2000 a 0.640 wavelength antenna. "
Tommy~852~CEF 750
Do They Make Anything Besides "GALAXY"?
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Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 2486
Registered: 9-2004
| | Posted on Saturday, April 14, 2007 - 10:53 pm: |
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they both work better with the counterpoise.
the difference is imax sells theirs separately.
without the GP radials, the maco V5/8 would resemble an old antenna design called the "ringo".
matt
anyone wanting a "clean signal", just look to the left and build one of these!!!
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Maxgain
Junior Member
Username: Maxgain
Post Number: 23
Registered: 3-2007
| | Posted on Sunday, April 15, 2007 - 9:50 am: |
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The "Ringo" was a half wave desighn. Half wave antennas do not require radials to function properly.
I had an A-99 (a halfwave) and put the radial kit on it and noticed NO difference on TX or RX.
I still don't understand how a 5/8 wave vertical can be desighned to operate normally without a radial system.
Whether you put the radial kit on it or not , the antenna is sold without radials and can be used that way.
HOW IS THIS POSSIBLE? Somebody must know.
Further comments? |
Caledonia
Member
Username: Caledonia
Post Number: 67
Registered: 8-2005
| | Posted on Sunday, April 15, 2007 - 6:40 pm: |
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I had a cheap italian made aluminum 5/8 wave antenna with no ground plane radials. That antenna worked great, I even had a 110 mile QSO with it one night.
Sadly, it was pretty junkie and flew apart in a thunderstorm wind one night. My roomate at the time converted the remnants into a 6 meter antenna and still uses it for that purpose. |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 2492
Registered: 9-2004
| | Posted on Monday, April 16, 2007 - 1:01 am: |
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maxgain,
i only used the ringo antenna for a visual referrence, not design or operation.
the groundplane radials are not for antenna tuning, they are for counterpoise which lowers the take off angle.
if you were to take the radials off of a maco v5/8 antenna, you would still be able to get a low SWR on it, but its DXing abilities would be somewhat diminished.
a 5/8 wave antenna benefits greatly from the use of a counterpoise, while it wont make much difference on a 1/2 wave antenna.
tech833 states this fact in his "imax exposed" article.
maco sells their antenna with the radials included.
imax sells them separately,
both are great antennas that will have very low take off angles if the radials are used.
they will still be good antennas without them.
matt
anyone wanting a "clean signal", just look to the left and build one of these!!!
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Tech833
Moderator
Username: Tech833
Post Number: 1659
Registered: 8-2002
| | Posted on Monday, April 16, 2007 - 11:56 am: |
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The Imax 2000 matching section balances the feedpoint inductance and capacitance adequately so that the ground planes are not required for a good SWR match. However, if you look at the polar plats with the GPK and without, you will notice a BIG difference in the way the antenna radiates! There are very few instances where I would not suggest the addition of the GPK to the Imax 2000. As for the A99, there are very few instances where I would suggest adding the GPK.
The Imax 2000 with GPK is very difficult to beat in fiberglass antennas. That is my first choice setup.
Marconi- The additional length is in the coil between the tap and the vertical element. Using the frequency selective TDR, the electrical measurement showed a .640 wavelength. At the request of the FM, I have to leave out a lot of the real technical info and make the reviews more 'readable'. |
Maxgain
Junior Member
Username: Maxgain
Post Number: 25
Registered: 3-2007
| | Posted on Monday, April 16, 2007 - 8:13 pm: |
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Thanks for the info guys ! This is good indeed! |
Dale
Advanced Member
Username: Dale
Post Number: 773
Registered: 12-2002
| | Posted on Monday, April 16, 2007 - 8:53 pm: |
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then we need to ask the fm why ya cant make it
more readable,.kinda makes it sounds like thier trying to hide something
dale/a.k.a.hotrod
cef426
cvc#64
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Forummaster
Moderator
Username: Forummaster
Post Number: 497
Registered: 11-2001
| | Posted on Monday, April 16, 2007 - 9:54 pm: |
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Dale,
There isn't anything to hide. I have asked Tech833 to write his reviews for the end user. He is quite capable of writing them for the antenna engineer but they aren't our target audience. If however you want to discus it with Tech833 on a more technical level feel free.
Forummaster
CEF001
CVC001
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Centurion
Junior Member
Username: Centurion
Post Number: 14
Registered: 7-2020
| | Posted on Sunday, December 06, 2020 - 10:07 am: |
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Does having Angled radials make any difference over horizontal radials |
Cedar_mountain_radio
New member
Username: Cedar_mountain_radio
Post Number: 3
Registered: 4-2022
| | Posted on Monday, April 25, 2022 - 9:03 pm: |
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I effected approximately 1 S-unit improvement in TX performance from my home on the valley floor to a 2500' elevation station 90 miles away, by adding three 1/4 wave (103") diagonally downward guy wires to the top U-bolt of my Imax2K, each terminating at an insulator, and non-metallic guy cord from each insulator down to the roof eyelet.
They were, I'd approximate, at a 60°- 65° downward angle - as the top set of guy lines on a 4-section push-up mast should normally be.
When mounted on the same mast, each antenna was 46 feet above ground to it's base. I left 24" inside each mast section for strength, but the top section was extended only 7' on a 13' high roof peak.
Before adding 3 wire "radials" to the Imax - my 1975-vintage Hy-gain Penetrator-500 beat it by 1 S-unit to the same station.
After the addition of the wire radials they were about even.
* * * * * * *
The Imax DOES require a 1/4 wave counterpoise in order to tune flat SWR, and it is using the mast or coax shield as such.
FOR A TEST:
I installed an Imax with the coax right below the connector wrapped into a 5T x 4x4 former CMC choke, because I wrapped the coax around the 20' long redwood 4by4 on which the Imax was mounted, set in a 24" deep concreted hole.
- The SWR raised to 3:1.
I then climbed the ladder, installed a 102" stainless steel whip into a hole I drilled into the aluminum mounting base - just below the top U-bolt, and tightened a nut to hold it,
- effectively adding a single 1/4 wave radial.
The SWR dropped to 1.2:1
<>—<> Sorry I'm 2 years late in adding this reply <>—<> |
Tech833
Moderator
Username: Tech833
Post Number: 2520
Registered: 8-2002
| | Posted on Monday, December 05, 2022 - 2:03 pm: |
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The GPK is the ground plane kit that I used in the Imax review. It changed the radiation pattern to be more favorable. Didn't make any difference on an A99 though.
Your radio 'Mythbuster' with Copper Electronics since 1998
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