Piggie

__________________
The more I understand, the less I know.

FOX TV

The one thing I did not mention due to the length of my post is that we went back for a second visit, and the viewer had someone to climb for him and he toted a C4 up with him and sat it on top of the chimney only 5 feet lower than his "100 miler " and it gained almost 5 dB over the C2 we used at 20 feet on the first visit. We hooked the spec analyzer to his antenna on the first visit and saw the echos out at 80 microseconds, with the RF levels of the echos that sometimes spiked almost as strong as the main lobe.

The C4 still showed the same time line, but the actual RF level of the echos we saw on his antenna were barely readable on the C4. I am not saying that there are not as good or better antennas, and i have no experience with Wineguard antennas which I understand to be good products. The tapered driven element design of the C series is very innovative, and In theory there should be an electrical path on the driven elements that coincides with every individual channel in the UHF band instead of a wire type element who's performance drops off above and below the design frequency.

Your point of elevation difference is valid, and I have seen evidence of this in the past myself, but since we were using a volunteer climber, and time was limited, we did not have a chance to do all of the desired checks we would have liked. This location would be an antenna experimenters dream, but a TV viewers nightmare.

I have built my version of the C2 that may violate the patent for the tapered loop design, but my feed point design and reflector is much different than theirs, and the Rhode & Swartz analyzer was used to tune it. My forward gain numbers are about 1/2 dB higher on average, and my reflection or rear rejection numbers are almost 2 dB better.

I have been designing or re-designing UHF antennas for years, especially concentrating on the multi-path we see in this area. Check out this article on my Gray-Hoverman re-design in TV Technology Magazine.

Polarized Power for TV Broadcasting, by Doug Lung

The design Doug Lung favored was mine, and this is not to toot my horn, just to give an idea of my background regarding antenna designs for the DTV revolution.

I won't flood this forum with posts, but I will chime in on antenna topics, for my efforts are now being aimed towards finding a way to reduce antennas physical size for high VHF, and to be able to build a reflector type antenna that works well on VHF, but is not so big that you would need a section of schedule 40 iron pipe to support it at 30 feet or higher.

Also, quads on 10 meters are killer antennas. I used to use an old PDL2 quad on a 50 foot tower, and it would break through the ces pool of noise you hear on contests and pileups etc. The PDL 2 is an old 11 meter antenna that I re-tuned for use on 10. I also installed 1/4 wave radial ground system on the tower that included a chain link fence that was a city block long and ran through 10 backyards before ending at the next block. My wife worked 10 more than I, and she did DX century in less than a year.

Piggie

Excellent, and yes I know who Doug is. I never doubted your results, just unexpectedly surprised, because all in all I really don't like that company.

Their idea on a tapered quad loop is a unique idea. But I think any thing short of their C4 is a waste of money, unless you have other data.

lol, that is funny, the Quad I built was from a PDL 2 parts. Also a really good 10 meter antenna I made was from a Moonraker 4 that had fallen (the directors were trashed)and was given to me. I left the quad reflector alone, then shortened the driven elements to 10 meters and adjusted the match. It was then 2 element, dipole driven and quad reflector. That antenna did just about as well as the coverted PDL 2.

Back before my ham license I built a 3 element 11 meter beam horizontal. I later replaced the reflector with a quad loop, imitating a moonraker. It helped a lot.

So despite stuff I have read that the quad reflector was a joke, I disagree.

Welcome to the forum, glad someone is here that has test equipment and years of experience so I can learn more!

I wish I still had my spectrum analyzer, but it was too expensive to just keep after closing my pager and 2 way repair business.

Thanks for posting and don't be shy or feel like you are displacing something I said. Please if you have any data that disputes what I say, bring it on or I will never learn more.

Piggie

__________________
The more I understand, the less I know.

Eureka

That antenna is unique. And they have another UHF-only antenna that has proven itself. However, I refuse to buy anything from a company that engages in such deceptive sales/advertising practices as the one that sells these antennas.

FOX TV

We do like the clear stream antenna, but really have not had a chance to compare it to any other brands of the "New Generation" antennas designed for UHF DTV. We did do a test a few weeks back using a C2 at 75 miles away from our 4000 feet transmitter on Rf channel 17 . We got very acceptable results using only 20 feet of mast pole. TV FOOL showed a good LOS which made it fairly easy to pick up.

We were trying to find the cliff so we could drive off of it, but at 75 miles out we still had around -65 to -70 dBm with a LOS using 35 feet of quad shield RG6 and a C2 at 20 feet. We were 75 miles out which is about 5 to 10 miles outside our 41 dBu contour, and we never did drive off of the cliff.

It looked as if it would have taken another 15 to 20 miles or more before we lost the signal to the noise, but it was a Friday afternoon, and we were already on volunteer overtime, so we turned around without finding the cliff on that day.

We have driven a lot of miles in the last 6 weeks or so, and we actually use 2 different antennas, with one being a Z Technology calibrated dipole and calibrated cable at 30 feet for channel power tests, and either the C2 or C4 depending on what levels we see using the calibrated dipole for the actual simulated viewer reception test.

Everywhere we go, we do both tests, and have found the c series antennas to perform well, but it would be nice to have some other brands and designs to compare it to. I met the owner of Clear Stream on their promotional tour, and he told me that they had a large grant from the NAB, and they were somehow financially backing the development of the C series antennas, and financed the antenna give away tour.

JER

Hi,

First off, let me say right up front that I'm the inventor of the Clearstream antennas. I work as a consultant to Antennas Direct as well as many other companies and agencies. If you're interested you can see my website at John Ross and Associates - Electrical Engineering so that you know what I'm all about.

Secondly, I want to say thanks to Fox TV for sharing his field testing experience with the Clearstream antennas. Antennas Direct and I appreciate the feed back and find it gratifying to see that our products being used and appreciated in your application.

Lastly, I'd like to discuss briefly how we came up with the Clearstream tapered loop / reflector idea and what factors tended to make it a success.

The Clearstream effort started out internally as an effort to create a very compact antenna to be integrated with a DTV converter box. We recognized that the antenna was key to such a product so we were focused on finding the most efficient, highest gain, directional antenna that we could fit in the smallest practical space and which would perform over the post 2009 UHF DTV band.

We looked at a lot of options but one option that looked interesting was the full-wave loop in front of a reflector. This geometry has been known for at least 5 decades to produce 9 dBi if you could feed it properly. Best of all the loop could be placed close to the reflector and still retain the forward gain. Right away we knew a thick loop would be required to cover the bands and we iterated solvers (NEC and X-FDTD) to do trade offs on loop size, thickness, reflector spacing and reflector size. Eventually we found one that worked good and covered the band but it still was too big to fit our package requirements.

My background is in UWB radar so one day I stumbled onto an IEEE paper where the authors were using tapered circular slots for pulse radiation so I tried tapering our loops and next thing you know we had better bandwidth and things really started to take shape. In backyard field tests our first single loop (C1) prototypes were performing as well as the double bowtie (DB2) but took up only 1/2 the volume so we began thinking of the antenna as something more than just part of a converter box part and went off and did the double (C2), quad (C4), and high VHF (C5). Other iterations are sure to follow.

In looking back on this effort several things stand out insofar as what makes a good DTV antenna for the MASSES:

1. Size - yes, size matters, the smaller the better or it won't sell

2. Size - the smaller it is, the more likely that it will go up on the roof. This dramatically improves reception almost every time!

3. Size - often referred to as Wife Acceptance Factor (WAF). It has to look good (aesthetics) or not be seen (better aesthetics). Ultimately it all boils down to size. See 1 & 2 above.


Now that we have the important stuff out of the way...

4. Impedance bandwidth - we targeted VSWR less than 3:1 across the whole band and achieved much better than that in most of it

5. Forward gain - We took what we could get, but the gain we got (approx 8 dBi for C1) was very flat versus frequency across the band.

6. 1/2 power Beam width (horizontal plane) - C1 has about 70 degree beam width on all UHF channels. Most antennas have beam width that decreases with frequency so the clearstreams should be easier to point.

Note - I personally think that sometimes people get antennas that have too much gain and beams too narrow to be effective in their markets. Channel surfing - even with a single TV - is so essential that the days of a rotator are pretty much done. I believe that a moderate beamwidth - say 50 to 90 90 degrees - may be a better for most folks.

7. Front-to-back - We took what we could get. The C1 has F/B of 12 to about 18 dB or so depending on channel. Higher channels were better.

8. Side lobes - Clearstream side lobes were generally much lower than F/B since the peak lobe is usually the rear lobe.

9. Forgiving structure - this is important for manufacturing and consumer installed antennas. We can have the best highly tuned antennas in the world but if we can't build them on an assembly line and have a consumer install them without needing an Agilent vector network analyzer then we've failed. The Clearstreams seem to be very forgiving to placement and since they are small we can ship them with simple (in some cases 1 bolt) assembly.

10. Pulse fidelity - This is speculation on my part, but Clearstreams are wideband structures that that can radiate / receive band limited pulses without a lot of distortion. While log-periodic dipole arrays are also wideband they do NOT do well when radiating / receiving pulses due to what is known as phase dispersion. I have a hunch that this may be one of the reasons that the Clearstreams sometimes do better than much larger antennas on digital signals, but have yet to prove it all out in a practical test.

Let me repeat, the above antenna considerations are for the masses, not the deep fringe enthusiast who has no problem with 80 ft towers, 10 ft booms and rotators.

Sorry for the long first post. I hope you all find the information useful.

Best Wishes,

John

PS - I too hate the rating of antennas with mileage. I'd much prefer to see all the gain charts and VSWR graphs on the box but the average Joe will have no idea how to interpret that so I fear we're stuck with miles...

Piggie

More than one person has come to this forum owning a C series and needed more VHF gain. I can't change my attitude toward their company based on exactly what Eureka said.

I have never doubted the antennas work for UHF, and even Ken Nist says the C2 is the best indoor antenna in it's class. No whiskers make it safer indoors than other 2 bay except the old Radio Shack later Channel Master indoor 2 bay, that is out of production (can't remember the number).

I would think to compare to a C4, a Winegard 7696p and AntennaCraft HBU33, should be all very close to the same class. I would guess AntennasDirect gave you the antennas? I know buying a lot of antenna just to test is about impossible to get into the budget, or it was where I worked.

If the NAB gave them a grant to design that antenna, manufactured off shore and financed what I called their snake oil tour, to me that deepens the manure in mind. I lost some respect for the NAB during this transition.

But my beef is with the company, and remain 100% open to results of antennas.. I no longer a fan of Channel Master, but their CM7777 still appears to be built as well as ever in China and I recommend it to deep fringe reception.

Please don't take my comments about Antennas Direct company the least bit personal. I really love hearing your test results.

__________________
The more I understand, the less I know.

JER

Some comments on the above post:

The Clearstream C1, C2 and C4 are designed for UHF but offer sufficient VHF reception to satisfy many people in urban areas. The vast majority of people who buy one of these antennas are happy with them.

The C5 is designed specifically for high VHF and is ideal for folks who already have good UHF installations but need more performance on high VHF. C5 is very compact and comes with a VHF/UHF diplexer. I think you will have a hard time finding a better high VHF antenna in such a small package. Some customers are also reporting that C5 also performs well on UHF but we don't spec it for that band.

C4 to the Winegard 7696p and AntennaCraft HBU33 is an apples to oranges comparison. The C4 is vastly smaller than either of the other two and thus aimed at a completely different customer. I've not tested or simulated them, but I'm sure the other Winegard and AntennaCraft are fine antennas for consumers that don't care about size.

The NAB funded the Antennas Direct / Viamorph team to develop a reference design for an indoor smart antenna. We are grateful for their confidence and support in that endeavor.

The NAB had nothing to do with the current Clearstreams or the Antennas Now tour. The Clearstream designs were done well ahead of the NAB smart antenna project and completed using internal funding. The Antennas Now tour was also financed internally, but the NAB was enthusiastic of our efforts in that regard since we were helping people rediscover free OTA TV.

During the Antennas Now Road Tour, company president, Richard Schneider, gave away untold thousands of antennas and helped countless numbers of people learn how to save money in a recession by switching from cable or satellite to free OTA DTV. He criss-crossed the country in his bus evangelizing antennas and OTA DTV to just about anyone who would listen. He was often up in the middle of the night giving TV interviews for the morning news casts and then spent the day at a local TV station or Best Buy parking lot helping average Joe's and Joanna's figure out how to solve their reception problems. That doesn't sound like a "snake oil" tour to me?

Antennas Direct, like most US companies these days uses off shore manufacturing. While I think most of us would prefer domestic manufacturing we all know the realities of that situation and its unlikely to change anytime soon. I recommend raising that issue with your elected representatives rather than here.

Thanks again for reading!

Eureka

All I know is that people in our area purchased the Clearstream antennas because they were touted as suitable for "all the DTV frequencies," which of course, is a crock. They were pss'd off after installing them, when they found out they can't get all their local channels because like most places, we also have VHF chs., which the clearstream can't receive here.

I will not recommend a company's products when they continue to engage in deceptive and misleading advertising, no matter how good the products may be.

FOX TV

EEEKK, I never wanted to get a discussion started about a companies ethics, or in some opinions, a lack of them. I am just an ordinary broadcast engineer who works in a very difficult TV reception market that has a mixed assortment of bands and transmitter locations. We operate two transmitters located in opposite directions, along with this being a LOW V / HIGH V / UHF mixed market.

Our field strength tests started about 3 months ago in order to compare the FCC coverage maps to the real world, and to help selected viewers with reception issues. Being a mixed band market has led me in a search for a compact VHF antenna that actually works well in a small package so that people would not object to its physical size, and not abandon the back plane reflector concept that works so well on UHF in killing ghosts.

I had a discussion a few years ago with a viewer who wanted a Direc TV waiver, and he said that he would not have an ugly TV antenna on his house. I politely pointed out that if he had a Direc TV dish mounted on his house that he indeed already had an ugly TV antenna mounted on his house, and that it performed the same function as an OTA antenna. I told him that his dish received digitally formated TV signals that he wanted to view, and it was no different than an OTA antenna that performed the very same function.

He did not even realize that his dish was a type of antenna. This sparked my interest in trying to reducing the size of a VHF back plane reflector type of antenna that we see in use on UHF with great success at addressing the multi-path issues we see with digital.

We cannot avoid the fact that the vast majority of consumer goods are manufactured in CHINA. If you want to stand on a high horse and buy American built products only, you will find great disappointment by not being able to find all of the products you need or desire. I object greatly to the "China Syndrome" myself, but this is the world we live in like it or not.

Every company in the world has some type of marketing strategy that is designed to produce maximum return on their investment, but that is where ethics come into play, and the ones who don't practice reasonable ethics at some point in time will cease to exist.

I still think I have proven to myself that the C series of UHF antennas work very well in this problematic reception market, and would be very interested in testing their VHF antenna in this area where signals bounce around like they are part of an old pong game from the 1970's.

We can all thank the FCC for folding to pressure and not limiting DTV to the UHF bands as was the original plan. Every time the Government has a chance to do it right, they seem to insist on screwing it up. I won't even mention health care.....