[stampeder]

This thread is for discussion of OTA Antenna Modeling Software such as 4NEC2, ezNEC, NEC II, and other such tools.

It is also for sharing ideas and concepts involved in OTA Antenna design.

Discussion of the Gray-Hoverman antenna design will remain in its own thread:

http://www.digitalhome.ca/forum/showthread.php?t=81982

 

[stampeder]

Links to the modeling software:

NEC2: http://www.nec2.org/

EZNEC: http://www.eznec.com/

 

[Autofils]

Web Link for Arie Voors 4nec2 modeling software program

The link to Arie Voors 4nec2 modeling software is:

http://home.ict.nl/~arivoors/

 

[300ohm]

4NEC2 Install

I installed the program, and it looks like its into 3 parts: the program, the build, and the view. Using F1 (help) brings up the message "Cannot find 4nec2.hlp". Is there such a file somewhere ??

Edit: Never mind, found it in the C:\4nec2 directory.

 

[vman41]

One project I want to do with the 4nec2 software is make a custom engine that can use both my CPU cores to calculate the NEC output. When it does an analysis now, the task manager show 1 CPU pegged and the other mostly idle.
The custom program will still use the same NEC programs underneath, but split the job into 2 concurrently running instances with staggered frequencies. The output of the two runs will have to be merged into the single output file that 4nec2 expects.

 

[rochmndx]

Channel Master Quantum VHF antenna

Is anyone interested in modeling/building the old Channel Master Quantum VHF antennas, like the 1110?

 

[fbov]

I'll raise my hand as another person who has downloaded 4nec2 and been able to run basic analysis of the G-H that fits with the expected results. I'm a physicist by training, but software inept so I expect a bit of a learning curve with the modeling programs.

I look forward to contributing ... eventually.
Frank

 

[stampeder]

Channel Master Quantum 1111 VHF Yagi

Is anyone interested in modeling/building the old Channel Master Quantum VHF antennas, like the 1110?

I own a never-used Quantum 1111 and here's the story of how I got it (sorry about the exaggerations LOL!)

http://www.digitalhome.ca/forum/showpost.php?p=200572&postcount=8

My property has too many tall trees on it so I've never put it up. I've only ever assembled it once for this photo then packed it away again:

 

[rochmndx]

Oh... by all means, please get us some dimensions/drawings!!

 

[Autofils]

Fractal Antenna Design for HDTV antenna ?

To go along with the NerdClub objective of "best of the best" hdtv antenna design, some of you might want to give
fractal antenna design a close look.

Most fractal antenna design work is being done at very high frequencies, but there are likely lots of UHF-TV possibilities that could be investigated with nec2 modeling analysis !!

Here are a couple of links about fractal antennas, to get you started...

http://en.wikipedia.org/wiki/Fractal_antenna#Log_periodic_antennas_and_fractals

http://www.hbci.com/~wenonah/cfa/fractal.htm

...autofils

 

[rochmndx]

After examining some pictures and diagrams of old Channel Master Quantum, Channel King and Crossfire VHF antennas, it looks as if the main active elements are for channels 2-6 (and possibly FM), and the little ones between these are for ch. 7-13. Can somebody help me out on this one?

Btw, is anyone willing to draw up their Quantum for me?

The fractal antenna design idea looks interesting, but it seems like they'd be pretty big at UHF sizes.

 

[stampeder]

Btw, is anyone willing to draw up their Quantum for me?

I don't know when I'll be able to unearth my CM1111 out of my garage but hopefully in the weeks ahead. I've always wanted to get out the calipers and blueprint it.

 

[rochmndx]

Sweet, thanks! If my assumptions are correct, the 1110 is a 1111 with a few added directors, so it'll be possible to finally model the greatest VHF antenna ever made!!

Next Sunday, I'm going over to a friend's house, and he has a Quantum 1162 or 3 U/V antenna about 10ft above ground (temp install), I'm gonna bring a tape measure and camera. I'll post the results when I get em.

 

[Autofils]

More Data on Channel Master CrossFire Antenna Line

I did a search for CM-1111 and all I could find was a reference to use model 3610, which was called a Crossfire model.
I eventually found a link that described the CrossFire line.

The Crossfire antenna line provides high gain across the entire bandwidth. The Crossfire’s performance is attributed to higher proportional energy absorption which means this antenna has more working elements per TV channel, thereby increasing antenna efficiency. When in a weak signal area and a high gain antenna is required, Crossfire is the antenna of choice.


Here is the link: http://www.solidsignal.com/channelmaster_antenna_chart.asp

If the model 3671 is similar to the 1111, man these are really huge !!
Length is 173" or almost 14.5 ft; turning radius of 95.7"
Width is 110', due to Ch2; Height is 35.4" due to UHF corner-reflector.

They were built to last, with double boom truss construction and reinforced element sleeves for added strength at greatest stress points on long elements and heavy-duty rear elements for greater strength..

Now there is a real-man's DIY and I thought the DBGH was large.


You can see the Raw and Net gain for the CM-3671B model at hdtvprimer.com web site "Comparing some commercially available antennas" here: http://www.hdtvprimer.com/ANTENNAS/comparing.html

UHF is "O" and VHF is "H".

 

[rochmndx]

One comment before I hit the sack: I've been scraping the depths of web and the internet archive for rare antennas and other old, forgotten antenna gear like this for, well... years. Infact, I've got a wiki in the works (being a student, I don't exactly have oodles of time to work on it).

I've got pictures and drawings of the old quantum and crossfire models. All I really need is some dimensions to work with. I'll be posting the collection soon.

 

[stampeder]

Autofils, the Crossfires seem to me to be Quantum-style VHF yagi antennas with UHF corner-reflectors in place of the 1111's directors.

I think another change was that the Quantums are golden-anodized, while the newer Crossfires are gray. Anyone ever seen a golden CM Crossfire?

When I blueprint my CM1111 we can hopefully check the spacings and measurements on the Crossfire's biggest model to see if that's what Channel Master did with such an amazing yagi design.

 

[Autofils]

Autofils, the Crossfires seem to me to be Quantum-style VHF yagi antennas with UHF corner-reflectors in place of the 1111's directors. I think another change was that the Quantums are golden-anodized, while the newer Crossfires are gray. Anyone ever seen a golden CM Crossfire?

When I blueprint my CM1111 we can hopefully check the spacings and measurements on the Crossfire's biggest model to see if that's what Channel Master did with such an amazing yagi design.

Stampeder,

Do you have any idea of the date of manufacture of the VHF CM-1111?
Was it before there were a lot of UHF OTA stations, hence the Crossfire CM-3671 was updated for the full VHF-UHF bandwidth?

It will be very interesting to see the actual dimensions and design detail of your CM-1111.
Does it have any capacitance-hats, that is described in this link for the CM-3671B ? (Photo shows 4)
http://www.hdtvprimer.com/ANTENNAS/CM3671.html

 

[rochmndx]

Ok folks, here's a Zip file with all the info and pics on Quantum and Crossfire antennas: http://radioguy.googlepages.com/ChannelMaster.zip

The Quantum 1160 line replaced the front VHF directors with a UHF Log antenna and director section.

 

[Autofils]

Net Gain CM-3671B Comparison

I took Ken Nist's data for the CM-3671B and re-plotted it to reduce the clutter as follows:

UHF - CM-3671B vs CM-4221 and CM-4228
VHF - CM-3671B vs VU-190XR; YA-1713 and 40" Rabbit-Ears

Added Note: In the VHF plot, the channel numbers for 7-13 are off by about 2-3 divisions, and should be moved to the right. Ch 2-6 and FM are reasonably correct

[The YA-1713 is of interest since it is a log-yagi designed for VHF-Hi (CH 7-13)]

You can view the the CM3671a.EZ file in 4nec2.
The CM3571a.EZ file is available at hdtvprimer.com http://hometown.aol.com/kq6qv/SIMS/

 

[stampeder]

CM4228 side screen

Have a look at one DHCer's successful solution to side-lobe signals overpowering his CM4228:

http://www.digitalhome.ca/forum/showthread.php?t=42423 Posts 645 through 652

Anyone interested in modeling it?