Vintage Channel Master Traveling Wave VHF Antenna

EscapeVelocity

Moderator, , Webmaster of EV's Antenna Blog
#1
Here is some detailed information on the vintage CM Traveling Wave, Id thought Id share...from Television Antenna Handbook, by Jack Darr, 1959.

The top and bottom pics were taken in the foothills of North Carolina recently, of a Traveling Wave still in use! HatTip, markdd @ DigitalHome.ca Forum.









 
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EscapeVelocity

Moderator, , Webmaster of EV's Antenna Blog
#3
I think its sufficiently different to be a unique design, and not a yagi. It's not log periodic either, but perhaps a precursor to the log periodic.
 

Piggie

Super Moderator
#4
Speaking to is this a yagi? Is this a log periodic?

First it's neither, though closely akin to both.

Yagi: The elements are dipole (folded dipole) in nature and the driven elements are in front of reflector. It has a central boom like a yagi. A lot of the similarity ends there.

Log: It has multiple driven elements like a log periodic. But beside using folded dipoles there is another major difference. Look how adjacent elements are phased. The are connected on the same side of the boom, where log antennas connect the next element to the other side of the boom.

The diagram 29 is priceless. Never seen it drawn out so well.
The fact that sweeping the elements puts the harmonic resonance in phase the point I mean in the diagram 29. This is also true of log antenna as far as swept element.

Log Periodic: A lot of the older log periodic TV antennas that don't have a corner reflector for the UHF part, make use of third harmonics of the TV bands. While the bands don't provide perfect third harmonics, they are close enough so a driven element on low band can be a reflector or directors on high band operating at a third harmonic. Also the same holds true between high band and UHF. As figure 29 points out, the elements need to be swept as that diagram notice the author shows the current on dipole type elements which a log periodic uses (not folded like a traveling wave).

This again proves, the best text on antennas came from the 1950 to 1980 era roughly. All stuff these days is how and which computer modeling program to use. The older text often puts it in simpler terms and very little has changed that wasn't known back then about antennas.

JER's CS design to me can be thought of as the marriage of two types of antennas.

1) The thick loop of vintage indoor UHF antennas of the other thread. http://www.dtvusaforum.com/dtv-hdtv...6-vintage-radion-uhf-indoor-loop-antenna.html

2) The bowtie antenna more like a Channel Master 4149 Double Bow Tie


The loop is known to have more gain than a dipole. Any antenna that uses thicker elements is broader in band width.

Then take the CM4149 and fold the ends of each bowtie in a loop, so the thickest part is at the top.

The CM4149 or any bowtie (sister antenna the whisker like a DB2,4 or CM4221, 4228) has more band width than a plain dipole due to the tapered elements. Hams have done this for decades. Instead of a single wire dipole, they would attache two wires to each side of the dipole (huge whisker). The placed an insulator at the ends of the dipole to separate the two wire by a fixed distance at their ends. They found on bands like 40 meters with it's high percentage band width they could cover more of the band with a low standing wave.

If someone had a LOT of room and big big tower, it would be interesting to build a 2 element 40 meter loop antenna antenna with each element two loops, maybe three, with them joining at the bottom feed point and separated by a spacer at the top. Each element would look something like a huge CS1 but with at least a reflector built the same way.
 

EscapeVelocity

Moderator, , Webmaster of EV's Antenna Blog
#5
BTW, Jack Darr's book is from 1959, I think the Traveling Wave was introduced by Channel Master in 1956 or 1957, about the fanciest VHF design at the time, dare I say it, innovative.
 
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EscapeVelocity

Moderator, , Webmaster of EV's Antenna Blog
#7
I spotted a Channel Master 5 element Traveling Wave mounted on an small old house, on Highway 61, while traveling across state via the backroads, South Carolina on the way back from fly fishing on the Chatooga River. I may try to recover it, as the house doesnt look occupied, though it was reasonably upkept, I might can track down the owner and do a swap for a Kosmic SuperQuad. The antenna is is fair condition though its feedlines are shot. For some reason the antenna is mounted upside down....pretty common for antennas.





 

tripelo

DTVUSA Jr. Member
#8
Traveling Wave (TW) Antenna with Extensions

Thanks EscapeVelocity, for the information and the article about the 'Traveling Wave' antenna.

These antennas were popular in rural KY, where I grew up.

There was a version of these 7-element TW antennas that had two additional elements in front and in back (four total). The additional elements did not have the folded appearance that the seven elements have (as in the photo earlier). The additional elements have similar appearance to ordinary reflectors and directors although they are Vee'ed. And, having two reflectors in the rear seems unusual (so I doubt they were strictly reflectors).

This summer, I discovered the remains of one of these 11-element 'TW-like' antennas in a metal scrapyard in rural KY.

Do you or anyone here have information about these 'TW-like' antennas with the front and rear extensions?
 

tripelo

DTVUSA Jr. Member
#9
The Wreck of an Extended TW

Shown below in a photo are most of the remains of an extended TW antenna.

The parts in the photo show only 6 of the folded elements. The center element had been cut out. Pieces of the center element were recovered but not included in the photo.

Extended TW _0705.jpg

At the ends of the antenna are four additional (two in front, and two in rear) not-folded elements.
 

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