Posts Tagged ‘Indoor TV reception’

Useful Gadgets: Wall-Mounted DTV Antennas Revisited

Last month, I tested a pile of wall-mounted indoor digital TV antennas to see if they really work as advertised.  Two of them (Mohu’s Leaf and the Walltenna) performed decently, while the amplified LeafPlus was a clear winner.

On the other hand, Winegard’s FlatWave was a disappointment, as it didn’t perform any better than a $4.00 Radio Shack bow tie antenna. That result led to a request from Winegard to return the review sample and see if it was defective.

It was, according to Winegard’s National Sales Manager, Grant Whipple. The culprit was (according to their email) “…a screw that was stripping and then causing a loss of contact between our circuit board and the antenna element itself.” Apparently this was an early production run issue.

Fair enough. Grant soon had a replacement back to me. Meanwhile, Scott Kolbe, who handles PR for Antennas Direct, sensed an opportunity and sent me a sample of their Micron XG indoor amplified TV antenna to test drive. The Micron XG isn’t a flexible, thin wall-mount design, but it is an indoor antenna and I decided to test it alongside the Winegard.

The Micron XG 'stuck' to the window. I never expected this to work -- but it did.

 

Here's what the Clearstream Micron XG amplifier looks like up close.

The tests, as before, were conducted at the offices of Turner Engineering in Mountain Lakes, NJ. I stopped by there after some RF interference testing in midtown New York City the Friday before Memorial Day weekend, and John Turner and I had the run of the place – everyone had gone home for the weekend.

To make things more interesting, I brought along the Mohu Leaf Plus, the original RS bow tie antenna, and my spectrum analyzer and digital camera.

THE TEST

John and I followed the same test procedure as we did in April. Each antenna was taped to the window with masking tape in the same position. A channel scan was performed with a DTV receiver (this time, it was Samsung’s DTB-H260F) and we verified dropout-free reception for 1 minute on each channel to qualify it as “received.” I also recorded the transport stream from each channel to check for bit error rates (BER) and recorded screen grabs of the actual waveforms for comparison among antennas.

Things started off again with the bow tie, which pulled in (unamplified) seven stations, all operating on UHF channels. The strongest local stations were WMBC-18 in Upper Montclair, NJ, and WNJM-51; also on the same tower. But the bow tie also snagged WNBC-28, WFUT-30, WPXN-31, and WXTV-40 from the Empire State Building, along with WFME-29 from West Orange, NJ. All seven stations were received reliably on the Samsung tuner.

Next up was the replacement Winegard FlatWave. After a channel scan, it also snagged seven stations including WNJB-8 (high band VHF!), WMBC-18, WNBC-28, WCBS-33, WXTV-40, and the 2nd minor channel from WNYW-44 (virtual channel 5-2). Of course, WNJM-51 also came in with no sweat.

 

Here's how WMBC-18 looked on the Winegard FlatWave antenna...

 

...and here's how the same station looked on the $4 Radio Shack bow tie antenna.

 

In essence, it was a draw between the $40 FlatWave and $4 bow tie. The FlatWave did pull in a high band VHF station, something the bow tie could not do reliably. But the bow tie snagged three UHF stations that the Flat Wave couldn’t reel in, one of which (WFME-29) was very strong on other antennas.

Just for kicks, I hooked up the original Mohu Leaf and let it do its thing. The result was nine reliable UHF channels, adding WNJU-36 and WWOR-38 to the previous lists. Catastrophe struck with the Leaf Plus, though – even though its power indicator LED was lit, absolutely ZERO signal passed through to the analyzer. It was cooked!

 

Here's what the UHF TV spectrum looks like with the amplified Micron XG...

 

...and here's how the same block of channels appeared with the amplified Mohu Leaf (not the Mohu Plus).

 

By itself, the Clear Stream Micron XG reached out and grabbed six UHF stations – WMBC-18, WNBC-28, WFME-29, WCBS-33, WXTV-40, and WNYW-44’s ’5-2’ service. WNJM-51 finished off the list. Not bad, but hardly an improvement over the bow tie. Adding the inline preamp netted three more UHF stations – WFUT-30, WPXN-31, and WCBS-33, putting the Micron XG on a par with Mohu’s basic Leaf. One caution – the in-line amplifier lets you kick in 5, 10, 15, or 20 dB of signal boost, but you need to use it sparingly – otherwise, you’ll ‘swamp’ your TV and create a lot of noise across the band.

Since the Micron XG preamp is a standalone product and works with its own power supply, we decided to have some fun and try it with the rest of the antennas. Hooked up to the bow tie, it delivered WNJB’s channel 8 beacon, plus WNYW-44’s ‘5-2’ service (whatever happened to 5-1?) and WWOR-38. Cool!

The FlatWave also benefited from additional amplification, pulling in ten different stations (WNYE-24 was the newcomer). But so did the Mohu Leaf, which snatched eleven different DTV stations, one of which was WNJB on highband VHF channel 8.  The table below summarizes the results for what are the nine strongest DTV station signals that could be received during the test. Each station’s call sign is followed by its physical channel.

 

THE RESULTS

A few solid conclusions came out of this re-test. First, the Mohu Leaf is still a formidable contender, amplified or otherwise.  Even though it doesn’t have much gain at highband VHF frequencies (channels 7-13), it also managed to pull in channel 8 with a boost from the Micron XG amplifier. (I’m still checking on what happened to the Leaf Plus.)

Second, I didn’t see much of a difference between the defective FlatWave and its replacement. True; the 2nd model fared somewhat better than its predecessor. But in terms of total stations, it didn’t do any better than the humble bow tie – it just substituted three different stations.

The Micron XG – which we actually wound up taping to the window for the test, using LOTs of masking tape – was a pretty weak performer without its accessory amplifier. However; with the amplifier, it was able to haul in three additional stations. But the Leaf did even better when amplified, capturing a test-high 11 stations reliably, one more than the FlatWave when it had a dance with the external amplifier.

Compiling the ‘yes’ and ‘no’ results into won-lost records, the Mohu Leaf finished in first place at 7-2 competing in the ‘no amplifier’ class, with a three-way tie at 6-3. In the ‘amplified’ division, the Leaf and FlatWave tied with 8-1 records, just head of the 7-2 Micron XG. (I didn’t list the amplified bow tie here, but it finished in 3rd place with a 6-3 log.)

How about performance vs. value? The Leaf is currently advertised on the Mohu Web site for $36, while the FlatWave is ticketed at $40. The ClearStream Micron XG will set you back $100 (the unamplified Micron A version is $60), while the humble bow tie is (gasp!) no longer listed on the Radio Shack Web site. (I guess it makes no sense to sell a $4 antenna when you can push a $20 Terk version that looks cooler.)

CONCLUSION

You don’t need to spend a ton of money to get decent DTV reception. In fact, you should be in good shape for no more than $40, based on my tests. If signal levels are really low, the amplified models will make a difference. Based on my tests, I’d suggest sticking with the Leaf Plus, as it is $25 cheaper than the Micron XG – and a lot easier to mount to a variety of surfaces, given how light and flexible it is.

And isn’t it amazing just how well a bare-bones antenna works? Higher cost doesn’t always equal higher performance. Caveat Emptor!

 

Useful Gadgets: Super-Flat Indoor TV Antennas – Do They Really Work?

Depending on you believe, Americans are fed up with ever-increasing cable TV bills and are bailing out by the thousands on channel bundles, opting for free, over-the-air HDTV and movies and TV shows streamed over Internet connections.

 

Or maybe not.

 

While there’s no question that a cord-cutting movement does exist, it’s hard to tell how big that movement really is. But the allure of dropping $50, $60, $70, or more from your monthly Kabletown bill is strong, and the recent battles between Time Warner and MSG network over rights fees only serve to highlight the inflationary spiral of pay TV services.

 

If you live in a metropolitan area and have the major networks (CBS, ABC, FOX, and NBC), chances are you already have access to quite a bit of sports programming. Maybe not the 24/7 deluge from ESPN, but you do have NFL games through 2022, selected Major League Baseball games, the NBA Finals, the NCAA Final Four tournament, college football and basketball, and numerous golf and tennis tournaments. (Oh, and let’s not forget next summer’s London Olympics on NBC.)

 

And if you aren’t into sports, that’s all the more reason to stop paying for programming you don’t watch. There’s still plenty of good prime time programming available for free, not to mention reruns of older cable network shows (Curb Your Enthusiasm was available recently on UHF channel 17 in Philadelphia).

 

With that in mind, I recently tested a pair of flat TV antennas for indoor reception. The first is the MoHu Leaf antenna (http://www.gomohu.com/) ,available direct from MoHu for $39.95 plus shipping, and the second is the Walltenna (http://www.walltenna.com/) , sold by a company known as Urban Freedom LLC for $40 (also at online stores).

 

Figure 1. The Walltenna is transparent and flexible (and maybe not too attractive).

Figure 2. Mohu's Leaf antenna is also flexible, but opaque and a bit less inconspicious.

Both are marketed to cord-cutters. Both companies cite the trend away from pay TV services “…as more and more viewers look for higher value alternatives” and “…and to get free from recurring monthly cable or satellite bills, high-maintenance rooftop antennas, or bulky tabletop models.”

 

Do they work? I tested both recently for wall-mount and window DTV reception, alongside two other stalwarts – Kowatec’s UHF panel antenna  (discontinued) and Radio Shack’s model 15-1874 ‘budget’ TV antenna. Let’s see how they stack up.

 

THE TEST

 

My house isn’t in the best location for indoor DTV reception. Although it’s less than 25 miles from the Roxborough (Philadelphia) digital TV antenna farm, there is a slight hill and a bunch of tall trees in the way.  Only a couple of UHF stations (17, 26) and one VHF station (6) are strong enough to come through without separate amplification.

 

The back side of my house looks north towards Allentown, which has DTV stations on channels 9, 39, and 46. And they’re not all that strong, either. In short, I have the perfect location to test these flat antennas – weak signals, but just strong enough to lock up a tuner.

 

To quantify my tests, I looked at the received waveform for each DTV station on an AVCOM PSA-2500C spectrum analyzer. And I used Hauppauge’s WinTV Aero-M USB stick receiver to verify reception and get some screen grabs of the stations that came in reliably.

Figure 3. (clockwise from upper left) The Walltenna, Leaf, Kowatec, and RS 'budget' antennas in position.

THE CONTESTANTS

 

MoHu’s Leaf antenna looks mysterious and ‘stealthy’ with opaque black and white sides, but hold the black side at an angle to a bright light and you’ll see exactly what’s going on under that “luncheonette counter menu” plastic housing: A pair of dipole antennas with X-shaped capacity hats at the ends.

 

The Walltenna takes that design and makes it larger, except you can see exactly what’s embedded in the plastic – copper foil shaped much the same way as the Leaf antenna. It just doesn’t look as nice on the wall as the Leaf, but then again, some of the best antennas have little eye appeal. (In the eyes of us RF enthusiasts, however, they are things of beauty.)

 

The significant difference between both antennas – and one which I figured ahead of time would give the Walltenna the edge in receiving more DTV channels – is that the elements on the Walltenna are electrically longer than the Leaf. This means the antenna should be resonant at lower frequencies.

 

I should point out that neither antenna uses a traditional collinear dipole array, as many rooftop and wall-mount UHF antennas do. With a collinear design, the physical connection ‘crosses over’ from one dipole array to the next, so that each X-shaped dipole array is out of phase with the one behind and/or in front of it, creating a broadband response. In the case of the Leaf and Walltenna, the physical connection to each ‘X’ element remains on the same side of the antenna.

 

Both antennas are designed to be stuck to a window or fastened to a wall. Mohu doesn’t provide mounting holes, but Walltenna does. On the other hand, Mohu has encased the coaxial cable connection to the antenna in a solid plastic block, while Walltenna simply solders a balun to the copper strips and attaches the balun to the plastic cover with a rivet.

 

I do not like the latter method at all. First off, inserting a piece of metal between the balun legs at such close range de-tunes the balun lines. Secondly, the balun is stiff enough that it provides too much torque on the base of the antenna when bent – you must be careful not to put too much strain on the connector, and the supplied RG-6 cable jumper is too stiff and heavy for the balun.

 

Mohu’s antenna comes with a long run of mini 75-ohm coaxial cable. This cable has higher signal losses per foot, but is much lighter and more flexible for indoor installations. Given the rough handling that such antennas are likely to receive, this is a much better approach.

 

THE TEST: ROUND ONE

 

My first test took place in an upstairs bedroom. I removed an oil painting and hung/clipped the antennas to the picture hooks. For comparison, I elevated the Kowatec and Radio Shack antennas and placed them in the same position. This wall position is on the part of my house closest to Roxborough.

 

After scanning for channels, the Walltenna snagged a few expected stations and a few that were not. Channel 6 (WPVI) runs tons of power to overcome interference from nearby FM stations (Channel 6 is at 85 MHz, and the first strong FM channel in Philly is 88.5). So it wasn’t a surprise to lock up.

Figure 4. (Clockwise from upper left) Spectrum analyzer waveforms of WPVI-6 as received with the Walltenna, Leaf, RS 'budget,' and Kowatec antennas.

Figure 5. (Clockwise from upper left) WBPH-9 and WHYY-12 as received using the Walltenna, Leaf, RS 'budget,' and Kowatec antennas.

Neither was WHYY-12, which also runs beacoup power now that they don’t need to protect channel 12 in Binghamton, NY. WHYY locked up just fine without dropout. WBPH-9 from Allentown was also rock steady.

 

So were UHF stations WPHL-17 and KYW-26, also a couple of powerhouses. WCAU-34 was mostly reliable with the occasional ‘hit,’ as was WFMZ-46 from Allentown, another strong station. (WBPH-9 and WFMZ-46 antennas were on the wrong side of my house.)

Figure 6. (Clockwise from upper left) KYW-26 as receivedon the Walltenna, Leaf, RS 'budget,' and Kowatec antennas.

Figure 7. (Clockwise from upper left) WFMZ-46 as received on the Walltenna, Leaf, RS 'budget,' and Kowatec antennas.

I could see RF carriers from other stations, but none were strong enough to lock up the Aero-M tuner. Even so, this was impressive performance from a so-called “all band” omnidirectional antenna. What the designer got right was to make the antenna elements longer, which helps with gain at highband VHF frequencies (channels 7-13). But it can also degrade performance in the UHF spectrum – you never get something for nothing.

 

By using a balanced line connection to the balun, that problem is overcome. At higher frequencies, only the dipole elements are active. At lower frequencies, part of the transmission line becomes part of the antenna. It’s a technique I’ve used for years on ham radio antennas and on my ‘ugly duckling’ UHF antenna prototypes from a decade ago.

 

So, how’d the Leaf do? Not too bad, but it only pulled in channels 6, 12, 17, 26, and 46 reliably. Channel 9 was nowhere to be seen, while channel 34 suffered from constant breakup. Odd, considering the Leaf is primarily a UHF antenna design and WCAU’s signal on channel 34 is one of the stronger signals around.

 

The fact that the Leaf pulled in both channels 6 and 12 is a testament to how much power both stations run.  This antenna also uses a balanced line feeder to its coaxial connection, which provides resonance over a wider range of frequencies.

 

But the ‘X’ elements at the end of the balanced line are only 4.25” long, whereas the Walltenna ‘X’ elements are over 7” long.  So the Walltenna has a decided edge in reception of VHF signals.

 

How about the two ‘control’ antennas? Kowatec’s panel antenna is usually a strong performer with UHF TV stations, but all it could receive reliably in the test position was WBPH-9, WCAU-34, and WFMZ-69. Radio Shack’s ‘budget’ antenna (UHF loop and rabbit ears) did marginally better, pulling in WPVI-6, WHYY-12, KYW-26, and WFMZ-46.

 

THE TEST: ROUND TWO

 

For the next part of the test, I hung or placed each antenna in a back bedroom window, facing north towards the Allentown and Bethlehem stations. Once again, channel scans were run using the Aero-M and screen grabs were taken of actual DTV waveforms.

 

I didn’t expect to pull in much from this location, save for WBPH-9 and WFMZ-46. The Walltenna met those expectations and also pulled in KYW-26 as a bonus, off the side of the antenna. The Leaf antenna located the exact same stations with comparable reception results.

 

The control antennas provided mixed results, but one did marginally better. Kowatec’s panel antenna snagged WPVI-6, WBPH-9, and KYW-26 (no sign of WFMZ-46 and its million-watt ERP signal), while the Radio Shack 15-1874 delivered WPVI-6, WBPH-9, KYW-26, and WFMZ-46.

 

Obviously all of the antennas could have been placed more carefully for optimum results. But how many readers have access to a signal level meter, or a spectrum analyzer? I’m betting  not many. So my methodology of just picking an arbitrary antenna position yielded a fair set of results.

 

CONCLUSION

 

There’s definitely something to the Walltenna design, but it’s not black magic. Just make the elements bigger and you will approach resonance at lower frequencies. The X-shaped elements on the end act like capacity hats and do the trick! (A full wavelength @ 175 MHz – channel 7 – is 1.7 meters, while a full wavelength @ 665 MHz – channel 46 – is .45 meters.)

 

The Mohu Leaf is a solid performer on UHF and will pull in the odd VHF station, if it’s strong enough. Both antennas are easily concealed, but take care in what you place them behind or near, as metallic surfaces will detune each antenna and the balanced feed line, degrading performance. (Tip: If a metallic surface is placed ¼ wavelength behind each antenna at the desired frequency, it will become more directional on the opposite side.)

 

As for the control antennas, they held their own in at least one test, so I can’t say that either flat antenna had a distinct advantage over the Kowatec and Radio Shack entries. Where the flat antennas have the upper hand is in design – they’re easier to hide and to look at . (Although Walltenna should really take a page from Mohu and encase their product in an opaque plastic coating. )