TV Antenna Story
With a loud clunk Matt shut the door of his truck and shuffled his way across the ice-covered parking lot of the service center. Since it was Christmas Eve, he gave the crew half a day off, but there was one lone car left. This was a very tired Chevy Cobalt which Penny, his part-time bookkeeper, used to make her way between the three part-time jobs she held in addition to going to school full-time to get her degree. Looking at the tired old wreck, Matt thought to himself, I’m sure glad she never asked me what I think about higher education.
She would get an earful. For Matt’s part, his formal education stopped with a high school diploma, which was gained not without a lot of effort. Nonetheless, the history and practical math skills he gained there were the starting point to his lifelong quest for knowledge, one that is with him to this day.
As he laid his hand on the shop’s door handle a strange thought snapped through Matt’s mind, This may be the second COVID Christmas Eve, a sad and dreary event, but I have a feeling that something is going to make this one very different.
Entering the customer area of the service center he felt the warm scent of wood smoke. There behind the desk was Penny, head down, thumbing back and forth on her smartphone, not noticing Matt until he stood squarely in front of her desk. Startled, she looked up, brushing the hair out her face. He saw the saddest, most downbeat blue eyes he had seen in a long time.
Matt said, “And the problem is?”
“Oh, this just came in from Amanda,” Penny said. “Remember her?”
“Yeah, she’s the one who has the aunt living on the back side of Plymouth Mountain, who brings her food and a lottery ticket every Friday morning, right?”
Before Penny had a chance to say a word Matt was thinking to himself, Lottery tickets are the stupidest waste of money. Taxation of the poor!
Penny read his face and said, “You don’t get it do you Matt?” I know it’s crazy but her aunt thinks she’s going to win the lottery and buy a college education for her nephew.”
Penny knew that for Amanda’s aunt this weekly visit was her only true connection to the outside world. Penny said, “This morning’s ice storm crushed her super-fringe antenna and last summer its antenna’s booster amplifier was zapped by lightning.” Thus her reception went from good to poor to nothing. Penny said, “Amanda tells me she’s heartbroken because she misses her friends on the 11 O’clock evening news on Channel 9, WMUR; the only signal she could receive.”
Matt said, “Yes, now I recall, she is way, way out there in the great north woods in the deep notch behind the mountain.” He went on to say, “OK, got it, another lousy Christmas gift,and if I understand things, the second wave of this ice storm is due tonight?”
“Matt”, Penny asked with the saddest eyes, “Is there something we can do?”
Matt said, “Er, do? I don’t know.” Doing anything caused Matt to drift over to his own Christmas “gift” of two more of his employees being poached by a competitor. Part of his COVID story is a staff that is slowly declining to the point where running the business is next to impossible.
Jolted back to reality, he exited this depressing thought, focusing back on the problem at hand. “Right”, he said, “WMUR, if I remember correctly, only briefly moved up to UHF when they went to high definition (HD) and so they are still on VHF channel 9 transmitting from the top of Mount Uncanoonuc down in Manchester?”(4)
Checking the web, Penny said, “Yes, they are up on the VHF high-band with a center frequency of 189 MHz which is Channel 9.”
Matt said, “Last time I hiked up North Uncanoonuc, I looked at their tower over on the South Peak, and I could see they are transmitting with circular polarization.” He went on to explain, “While the radio waves may start out that way, by the time they gets refracted off the top of Plymouth mountain to get down to her place it must be a real polarization mess due to the knife-edge effect.”
“Knife-edge, what’s that?” asked Penny. With a wry grin Matt responded, “You’ll find out in a little while.”
Matt said, “OK, so we need a deep-fringe Channel 9 TV antenna with circular polarization and plenty of gain made out of aluminum foil and whatever other junk is lying around the shop on Christmas Eve. And where do we get these plans?” Matt asked with a smile?
Penny said, “I know just where – the place you say is better than a thousand YouTube videos, the expired patents.”
Matt said, “That’s it and as I have always said, the bigger the company the better job they are going to do explaining how to exactly duplicate their invention, antenna or whatever it is.” He elaborated, “This is in order to best protect the claims of the patent, which is what they own for the rest of its life.” In trade for this monopoly the Government requires that anyone can replicate and use the invention after the patent expires as it is then placed in the public domain.
Matt said, “OK, Penny get on freepatentsonline.com and use the search terms of “Circular Polarization” for the patent abstract and “Raytheon” for the assignee. Please arrange to show the oldest patents first.”
With some maneuvering with her keyboard, the big screen TV that filled the entire wall of the customer area of the service center was changed from pitching the latest features of Kohler Generators to a giant view of expired U.S. Patent 3,665,480 assigned to Raytheon in 1976, which explained exactly how to make the antenna(1).
As Penny scrolled through the patent Matt asked her, “So you know the drill here?”
“Got it boss,” Penny said, “First read the body copy and then compare it to the claims. In particular Claim #1.”
“Exactly”, Matt said “As the claims define the really important features of the invention and the body copy teaches how to build it.”
Reading together, they found the description of Figure 6 very helpful and in particular, Column 3 Lines 25 through 32 explained the entire design. Matt, half talking to himself, mumbled “Half wave, circular slot antenna – never tried to build one but this is everything we need except for one thing. We need gain.” For that let’s use the K7MEM VHF yagi beam calculator on the web to figure out the reflector size and distance from the driven element.” (3) Matt said, “Penny, since you’re the math whiz around this shop, what we need to know is how much larger the reflector is compared to the driven element, or receiving element in our application, and element spacing at this frequency along with the dimensions of a circular slot antenna slot at 189 Mhz using the teachings of the 480 art.”
Made From Found Parts
A short while later, Penny had all the numbers together and she said, “OK boss this is what I have for a 2% bandwidth annular slot antenna which spans the WMUR TV signal running from 186 to 192 MHz and with 4dB gain.”
Here are Penny’s calculations: (4)
Receiver Slot Element
Outer Circumference: 10.2 inches
Inner Circumference: 9.8 inches
Feed Probe: About 12 inches
She explained to Matt, “The reflector has a 1.5% larger diameter and is spaced 12 ½ inches from the receiving slot element.”
Contemplating the design, Penny observed, “I like your idea of using aluminum foil for the antenna elements but how are we going to bond the aluminum to the feed line shield?”
“Can’t solder to aluminum,” she said with a note of discouragement.
Matt said, “Good call Penny but I have just the answer: This jar of electrically conductive Wire Glue from Anders Products bonds copper wires to aluminum, so at least that problem is solved.” Penny then asked, “In order to get this antenna to provide a super-strong signal couldn’t we put two of these in parallel and get a better signal like batteries in parallel?” “Yup,” Matt responded. “It can be done due to one of the inventions of the Father of the modern TV antenna, John Winegard.”
If the reader would like to learn more about how this antenna was built I have moved this conversation over to a separate section called, “Part 2: How the TV antenna was made.”
A short time later they threaded a string through one of the rafters in the repair bay and hauled the antenna into the air. With a big grin Matt exclaimed, “This test data looks just great!” But just then the next wave of freezing rain started to drum and crinkle on the steel roof of the building.
“Or not,” responded Penny grimly to the unwanted staccato noise. “But we have to do this Matt as after all, it is almost Christmas.”
Without answering the question, Matt said excitedly, “Grab that roll of RG-6/U coax, the tools and let’s go.”
The first part of the drive up north on Interstate 93 was OK as the road was well treated.
Staring out the windshield into the swirls of snow mixed with ice coming down, Penny’s mind turned to some really dark thoughts. Probably what triggered her into such a deep slump was when she learned of Amanda’s aunt’s troubles, and the way one more little trouble is just more fuel for the fire of the big one.
For Penny, Northern New England had been and she had hoped would forever be her home. But she knew under all this crushing student debt, her three part time jobs were just not enough. In particular, with very high costs of living up there she knew the only solution would be to move someplace where the cost of living is low and high paying jobs plentiful. North Carolina? Georgia? Some place South. Get full time work doing something and try to pay off that strangling debt.
This was not a new plan but an old plan with the intention to resign on January 1st. Now just nine days away, she was dreading every hour till that moment. She knew full well how Matt’s labor pool was disintegrating and how she from time to time was being sent out on jobs to fill in. Frankly, she liked the work and most of all she liked working for one of the smartest men she had ever known. No question this news would be devastating for Matt. But what else could she do?
Matt turned off Interstate 93 and started heading west on Route 25. The driving was getting really bad. The sound of the studded snow tires on the pavement for a few moments was followed by the hush as the truck rolled over packed snow and ice.
Despite the weight of the ¾ ton truck and the power of 4-wheel drive, Matt was struggling to keep the truck heading straight. He said, “To give me a break from this driving misery,” he said to Penny, “lets talk about anything to get my mind off this ice storm.” He went on to say, “So Amanda’s aunt likes the 11 O’clock news. Why? She thinks the weather man, Mike Haddad is cute? That’s a little more than I can understand.”
“Well”, Penny said, “They are her friends, and as we are all lost in the sea of COVID, I think that friends, no matter where you find them, are so important.”
“Got it”, said Matt. Their conversation drifted on as the roads became narrow and the storm more intense
Fortunately Penny knew how to find this place, as it was a tiny, single-wide trailer way out in the deep woods. The little trailer was perched up on a rise and as they approached the home they could smell a wood fire furiously burning. With a slight tap on the door they were invited into this little place by an older woman, and although a stranger to both of them, a truly welcoming person. Matt glanced at her clock and said “It’s getting close to 11 PM and we need to get to work.” “Oh, you’ve heard that story?” she blushed. “Yes and we’ve got a job to do,” Matt responded with a smile.
Matt dug out the antenna, now attached to an old camera tripod and a plastic tarp which served as its raydome. Penny ran the coax from the antenna up the front steps and over to the TV, hooked up the coax with crimped-on F-Connector.
“So you wanted to learn about the knife-edge stuff?” Matt said to Penny. He went on to say, “Let’s get on 55 direct, using our ham radio licenses, in order to keep the amateur radio 2 Meter national call frequency 146.52 MHz clear. I will watch the signal strength bars on the TV as you wander up and down in front of the trailer in order to find the best picture as you keep the antenna pointed to about where the peak of Plymouth mountain should be. Because we are picking up the knife edge diffracted signal off the peak, you will need to move about two wavelengths, or about 6 feet, to find the next signal peak. By that I mean, you will be doing your best ice dance!”
Back and forth she wandered with tripod in hand, while they chattered back and forth on 55 direct. Eventually she found the best hot-spot on a snow mound which in the summer would be a picnic table but was now buried deep below the snow.
Around this time the storm really started to blow hard and by the time Matt swung open the door and looked down the little rise to invite her back inside, Penny was covered with a gleaming coat of ice. For a moment, Matt paused and stared at her. She was a gorgeous sight with the beautiful face of a real ice queen.
By the time this was all set up the 11 O’clock news has come and gone. The last item up was the lottery drawing. Looking over Amanda’s aunt’s shoulder, Matt read the numbers off the screen and compared them to the ticket in her hand.
First three numbers were a match. Just luck, he said to himself.
The next three numbers were a match. Oh boy, Matt’s heart was starting to pound.
And the last three numbers: A match.
Matt was nothing short of stunned.
The next thing Matt heard was Amanda’s weeping aunt. She cried, “I did it!” “It’s paid for college. Now it’s possible!”
Yes, Matt said, very slowly, “You are now a multi-millionaire.”
But her gaze bypassed Matt and went directly to Penny; “Amanda tells me”, long pause, “that you are drowning in student debt?”
Penny nodded back.
“Well whatever it is, it is now paid by me. Done!”
“And, Merry Christmas!”
As the truck backed out of the drive and onto the country lane, out the windshield this time Penny was greeted with a new view. The storm has changed from ice over to snow and the dazzle of the headlights revealed a beautiful blanket of fresh white powder.
The beauty struck her and she started to mumble something to Matt.
“What’s that?,” he asked.
Penny said, “I just got the best Christmas present of all. Hope.”
Epilog: As the next Christmas was approaching the dark clouds of an impending economic recession were starting form across the world. So Penny and Matt decided to build a batch of these antennas for indoor next-to-set placement and give them to needy families whom could no longer afford their cable bills. One of these antennas is shown in the top of this page and as Penny explained, “Built from a couple of discarded corrugated boxes and aluminum foil, it is amazing all the stations this antenna can pull in because of it’s powerful beam design combined with the advantage of circular polarization.” Matt added, “Since we didn’t need super-fringe performance, we just bent the feed probes to match the pictures on this page and did the final tune-up with the signal strength bars on the TV screen. No test equipment needed!”
For the their installations in Southern New Hampshire they would pick up 8 digital stations with the indoor antenna while the Boston area and along the South Shore 12 or more.
They both sincerely hope you will consider building a couple of these antennas and give them to needy homes as well. Possibly an elderly shut-in or a young family with growing children. They all need your help and kindness
1. U.S. Patent 3,665,480 assigned to Raytheon