Antennas Direct's Clearstream2 Antenna Available for Pre-Order

[ragnars]

PR claims are nothing new. In the 60's I worked for an antenna manufacturer and we stamped the cartons of our antennas with "Approved for Color", even though the same antennas had been sold for ten years for black-and-white TV reception.

For purists it is worth noting that the magnitude of the "gain-bandwith product" (which is constant) of an "electricaly small antenna" will always be less than that of a full size (compared to wavelength) design.

Therefore, if you want the best, accept the size (and bandwith limitation) of, say, a single channel Yagi. Everything less is a compromise. But we all live with compromises.l

[akirby]

[quote="rschneider"]While it

[rschneider]

I appreciate that this isn't turning into a flame war.

About some of the marketing hype. When we started in 2003 I was just going to focus on home theater enthusiasts like myself. I assumed that most people were familiar with the basics of OTA and the frequencies where the digital stations were broadcasting.

Our first version of the DB2, the package said: "UHF antenna - Channels 14 -69" Imagine my surprise when we had scores of complaints from irate people that wanted an "HDTV" antenna not a UHF antenna. Some customers were insistent that their channels were on 5.1 or 2.1. Dozens actually refused delivery of their antenna. The experience cost us thousands of dollars. I finally got tired of arguing with people and changed the box to read HDTV antenna, we kept "UHF antenna" but in smaller type. Was that deceptive? I don't think so; the customer got a reliable antenna, our rates of returns dropped by 70% and we both avoided some confusion and aggravation.

2009 will make matters even more confusing for customers. Many of the station engineers I have spoken with are planning on keeping their current VHF channel identifiers (2.1, 4.1 5.1 etc...) after the 2009 shut off. This will create even more confusion in the marketplace when people (mistakenly) seek antennas which are suited for low VHF. Can you understand why I'm keeping "HDTV" antenna on the boxes?

The antennas are optimized for 470 -700 MHz, should we say that instead? Does the general population know what that frequency represents? I admit I have to walk a line here. If all of my customers were educated as the readers on the forum, all I would need to do is post the specs on the box and let the market & word of mouth do the rest.

To make matters worse, we had a buyer from a

[kq6qv]

Richard- The flaw in your reasoning is that the VHF channels are not going away, the day of the combo antenna is not over, and some of your customers are going to be angry with you on Feb 17 because their

[rschneider]

I guess I didn't make it clear, one of the primary reasons we are migrating to the Clearstreams was to improve our capabilities on high VHF. Trust me, I have the list, We are very aware that 24% of the DTV stations will be on the high VHF band, post 2009 (about 400 stations). The necessity to cover both bands was why we started this project in the first place.

While it won't have the same range as on UHF, The Clearstream 2 offers modest performance of about 3.7 - 4.4 dB between 174 -216 MHz. (less than the VHF performance of our larger combination antennas) The single hardest part of the entire effort was trying to cover both bands with one design while not compromising the UHF performance.

While there have been some recent improvements, Bowties can have a problem with pattern & impedance. Specifically at high VHF, additionally, the reason for the decreased high VHF performance of bowtie antennas is the result of the phase reversal on the transmission line connecting each pair of dipoles. At high frequencies this phase reversal is necessary to compensate for the added distance between the feed point and the outer pair of fan dipoles. At lower frequencies however the phase reversal results in over compensation causing the signals received by the outer dipoles to cancel the signals received by the inner dipoles. The cleaner structure in the Clearstream tapered loop elements to the feedpoint as well as some cunning engineering has resulted in much improved high VHF performance. We have made no attempt to cover low VHF however, since we have not found a way to incorporate low VHF capabilities without severe penalties to the UHF performance.


For existing UHF antenna owners, this fall we will be releasing the Clearstream 5, a high VHF only design bundled with a UHF/VHF diplexer. (We'll unveil it at CEDIA) It will have directivity of about 9.5 dBi between 174- 216 MHz, and will have a form of 20"x 24" x 6" - about the same size as a DB4. The majority of the Clearstream owners however should be fine without the need for a supplemental antenna to cover High VHF.


( just FYI, we have offered the V10, High VHF/UHF antenna for about 4 years)

[kq6qv]

I spent the last couple days modeling this antenna. Things I discovered:

1. On UHF, it matches the performance of the DB-2 despite being 20% smaller.
2. Its raw gain on VHF-high is above 4 dBi as claimed, but the SWR was always above 100. I found some circuits that would match it, but the resulting bandwidth was always about 1 MHz, which is completely useless for TV.

Unless I am overlooking something, this is not a good VHF antenna. Its typical maximum range for UHF is maybe 20 miles. (It will work at 50 miles as claimed but only if it can see the transmitting tower.) But its typical maximum range for VHF-high is maybe 4 miles. A viewer who needs a 20-mile UHF antenna likely also needs a 20-mile VHF antenna, given how the towers for a city tend to all be in the same place. So it is very unlikely that this antenna can be counted on for both UHF and VHF-high.

Somebody is wrong here. I do not think it is me, but I will keep an open mind. I do not have the antenna. I have been working from a picture of it. I have no idea what matching circuit they chose. Perhaps AntennasDirect has found a magical way to match the antenna. -Ken

[musket3]

Does anyone have any practical experience with one of these antennas? I would like to purchase an antenna for my location in Whiting, Manchester Twp, NJ 08759. I am 49.5 miles from Philadelphia and 58.5 miles from New York City. There are no homes with outdoor TV antennas anywhere around here. I have DirecTv now but I would like to at least add Philly's baseball, channel 57, for next baseball season. Does anyone have any suggestions? I live in a location where I may have to present the FCC OTARD rule to the management. I would prefer something small and inconspicuous rather than argue the point. Thanks for any suggestions.

[kq6qv]

A ClearStream2 is out of the question for you since WPVI-DT will move to VHF channel 6 on Feb 17. WABC-DT in NYC will move to VHF channel 7 on the same date. Your situation is complicated. You will need much of the advice at www.hdtvprimer.com/ISSUES/erecting_antenna.html . -Ken

[eliwhitney]

Hello kq6qv -

Since the production of C.M. 4228 great unit has ended, is there any "timetable" for your evaluation of it's "replacement" unit by them ?

Thanks.

eli

[kq6qv]

Eli- It is on my list of things to do, but it is pretty far down the list. Maybe by March. Until then I will not hesitate to recommend the replacement unit. -Ken