Posts Tagged ‘Indoor TV reception’

Useful Gadgets: TERK Omni and Turbo Indoor DTV Antennas

I have to give Terk credit for continuing to roll out innovative designs for indoor and outdoor TV antennas.  Going all the way back to 1998, when I tested my first Terk design, there have been some pretty interesting-looking products in their line (not to mention some strange ones, too!).

Unfortunately, the performance of these antennas hasn’t always matched up to their looks, and the new Omni and Turbo indoor models aren’t breaking that mold any time soon. The bar that any indoor TV antenna must overcome is pretty high: They must have gain at the specific frequencies; enough of it to overcome multipath distortion and echoes – a given indoors – and also to provide a sufficiently-high signal-to-noise (SNR) ratio so that reception is free of drop-outs.

The Omni (model OMNITWR, no price yet) is a black plastic tower that stands about a foot tall and has a blue LED illuminating ring on the bottom. Terk calls this an “amplified multi-directional HDTV antenna” which “receives 4K Ultra HD Broadcast” (never mind that there aren’t any yet) and “Supports 1080p.” The packaging goes on to promote free HDTV from the familiar networks (ABC, CBS, Fox, NBC, CW, PBS, and Univision) and proclaims it is “a great compliment to streaming players.”

Well, Terk and I agree on that last point, at least. Free off-air digital TV is a great compliment to streaming channels. If you can get CBS off-air, why pay $8 a month for it? For sports fans, there are still quite a few marquee events that are broadcast on free channels, and for ‘retro’ fans, more and more secondary minor channels like Antenna TV, Comet, and MeTV are full of classic old TV shows (many in thrilling black and white!) from the 1950s, 1960s, 1970s, and even the 1980s.

Elsa can’t figure out if the Omni is a scratching post or not.

As for Terk’s other claims; antennas pull in RF signals, such as TV channels. Those channels can carry digital information in the ATSC format in the U.S. or in the DVB format used elsewhere in the world. The demodulated broadcast signal can be standard definition (480i) or HD (720p and 1080i). It’s the TV that demodulates the signal, NOT the antenna – all the latter does is receive the RF channel.

So technically, the Omni (and any other indoor or outdoor antenna, for that matter) can receive 4K broadcasts. They could also receive 1080p HD broadcasts, although that format isn’t used by any television station. Yes, the $4.99 bow-tie antenna I use in all of my tests could also receive a 4K broadcast! (How’s that for mixing contemporary with retro?)

Terk’s Trinity Xtend Turbo antenna (Model WITRIAC, $129.99) is another indoor antenna design that is shaped like a book. You can lay it flat or mount in vertically for TV reception. But it does double duty as a WiFi extender, working with dual-band (2.4 and 5 GHz) systems that use the 802.11ac channel-bonding protocol. So you can watch TV and extend your WiFi range, too!

The shipping box touts “802.11ac up to 3X faster than 802.11an.” Well, that should be the case, as you can bond two, three, and even four channels in the 5 GHz band to increase data speeds, but that’s a WiFi protocol not related to DTV reception. As before, Terk claims this antenna will receive 4K broadcasts and supports 1080p, and we don’t need to go down that road again.

But there’s one additional claim that was hard to swallow: A reception range of 65 miles, which would be some manipulation of the laws of physics for such a small antenna! I’m hard-pressed to receive signals that far away using a combination 5-element VHF and 15-element UHF antenna system equipped with a 24 dB mast-mounted preamplifier. But I suppose it’s possible that reception over that distance might be possible if (1) you lived on a mountaintop with a long view to the horizon, (b) happened to be watching UHF TV channels during a tropospheric ducting event, or (c) were watching terrestrial TV on the international space station.

I tried the Trinity Xtend horizontally polarized…

…and vertically polarized.

ON THE TEST BENCH

All’s fair in love and war, so I decided to test both antennas against my reference bow tie antenna. There’s a sweet spot in my 2nd floor home office where DTV signals from Philadelphia are strong enough to be captured with an indoor antenna, so I ‘borrowed’ my cat’s elevated perch and use that to support all of the antennas. Just for fun, I dusted off an amplified Mohu Leaf to compare tests, and to provide a bit more ‘kick’ to the bow tie, I pulled out the Antennas Direct ClearStream JUICE preamp so that all antennas were playing on a more level field.

Each antenna was placed in the ‘nest’ and aimed for best-looking waveforms on a spectrum analyzer. Then, I scanned up and down the band to find which channels were received reliably, i.e. that is for at least a minute with no dropout. In the Philly market, we’ve got a couple of low-band VHF stations, a few high-band VHF broadcasters, and more than a few UHF signals that should be easily received.

Laugh if you want at this ancient antenna design, but it can run circles around upstarts!

 

Table 1. A comparison of all the antennas under test. None of them could pull in WTXF on channel 42.

Table 1 shows the results. I was quite surprised by how well the bow tie performed, but perhaps I shouldn’t be. This classic design more than holds its own repeatedly in tests against more expensive models with gimmicky packaging, and it’s over 60 years old. With the JUICE preamp, it pulled in eight out of ten stations, missing WBPH-9 and WTXF-42. (None of the antennas could help Fox’s signal, despite it looking pretty clean and strong on my analyzer.)

2nd place went to the UHF bow tie without the preamp, which hauled in seven stations. Not bad for $4.99! Mohu’s time-tested Leaf with external amplifier was right behind, providing reliable reception of six out of ten stations. Terk’s Omni was not up to the task even after I tried a second position for it, pulling in four out of ten stations the first time around and three of ten on the second try. In its defense, it did snag WLVT-39 from Allentown, which only the amplified bow tie could match.

Compact antenna designs will have trouble with low-band VHF reception.  KJWP-2 and WPVI-6, as picked up by the amplified bow tie…

…are basically ‘missing in action’ on the Terk Omni antenna.

As for the Trinity Xtend? Best to use it as a WiFi extender and forget about DTV reception altogether, unless you live very, very close to the transmitters. No matter which way I oriented it – vertically or horizontally – it could only pull in two stations reliably (WYBE-35 and WFMZ-46) and neither of them is affiliated with a major network. (So much for the claim of 65-mile reception.) My location is around 25 miles from the Roxborough TV towers and has moderate multipath, but not so much that the average indoor antenna can’t pull in at least five stations.

As for the WiFi extender part; it works quite well. I downloaded the Terk Extender app from Google Play and it didn’t take long to make the connection while following the app’s instructions, boosting 5 GHz signal strength by a few decibels in the farthest parts of my house. So you may still find that part of the product useful if you are strapped for range.

Terk’s Trinity Xtend created a ton of spectral noise on high-band VHF channels 7 through 13…

…that wasn’t seen at all when using the amplified Mohu Leaf.

Here are channels 17 through 46 as picked up by the amplified bow tie.

The same channels using the Terk Omni…

…and the Terk Trinity Xtend, lying flat (horizontally polarized).

CONCLUSION

As you’ve seen in previous tests, there are some really good indoor antennas for sale that won’t break the bank. Winegard and Mohu both offer indoor panel antennas (passive and amplified) that should pull in the majority of stations in your area if you are no more than 30 miles from the TV transmitters. Radio Shack doesn’t sell UHF bow ties anymore, but Amazon shows the ANTOP amplified bow tie for about $28 – a little pricey in my book, but having the amplifier is a plus.

There’s a catch, though. The recent FCC spectrum auction just concluded and it appears that all UHF channels above 38 will be re-allocated for other uses. This means there are plenty of TV stations that will have to relocate, and some of them will wind up in the noisy, harder-to-receive low-band VHF channels from 54 to 87 MHz. Antennas must have more and longer elements to work at these frequencies, so super-compact designs aren’t going to cut it in the future.

With that in mind, I can’t recommend either of the Terk models for indoor reception – not when a five-dollar piece of bent wire can outperform both of them. Oh well; better luck next time…

Broadcast TV Spectrum Repacking: The Devil Is In The Details

The FCC has concluded its spectrum auction, and although the winning bids generated only about ¼ of what was expected, plenty of TV stations will be moving to new channels.

But there’s a catch. And you probably won’t be happy when you hear about it.

Currently, the majority of TV stations broadcast in the UHF television spectrum from channels 14 to 51. Another smaller block of stations use the high band VHF channels (7 through 13) while fewer than 50 stations transmit on low band VHF channels (2 through 6).

That is certainly going to change, as it appears all UHF TV channels above 37 will be re-allocated for a variety of services, including Wi-Fi, mobile phones, and a bunch of other “white space” operations. There may even be a few TV stations still mixed in with these services, and we won’t know how broadcasters will be re-packed until early April.

Finding new channels for broadcasters who gave up their channels in return for some nice cash will be a pain in the neck. And it will certainly require some stations to move back to those low-band VHF channels, which were once desirable back in the early days of television (Channels 2 and 3 were ‘golden’ then), but now make up what’s essentially the low-rent district of TV broadcasting.

Why? First off, much larger antennas will be required to receive these stations. A full wavelength at 56 MHz (channel 2) is about 5.4 meters, or about 17.5 feet. So a somewhat-efficient ¼-wave whip antenna to pull in that channel needs to be about 4.4 feet long. (Now you know why grandpa and grandma’s TVs had those long ‘rabbit ear’ indoor antennas!)

That’s not to say you can’t pick up these channels with smaller antennas – if the signal is strong enough, you probably can. But that means being much closer to the transmitter than you’d need to be with a high-band VHF or UHF signal, as it’s easier to design antennas for those channel that have some gain.

Here’s another problem. The spectrum from 50 to 88 MHz is historically plagued with interference from impulse noise (vacuum cleaners, electric motors, switching power supplies, lightning and other static). And during certain times of the year, atmospheric enhancement of radio signals occurs where distant stations will come in stronger than local stations, creating plenty of interference (ionization of the E-layer of the troposphere, a/k/a “E-skip”).

While the high-band TV channels are also susceptible to man-made and natural interference, it’s not as much of a problem. And UHF TV signals are essentially immune to impulse noise, although they can also experience signal ‘skip’ conditions; particularly in the late summer and early fall with tropospheric ducting.

During one of my RF and wireless classes at InfoComm, we aimed an antenna from the 2nd floor North Hall meeting rooms toward Black Mountain, a line-of-sight path parallel to the Las Vegas Strip, to try and bring up channel 2 (KSNV). Guess what? We couldn’t even find the signal using a spectrum analyzer, due to all an extremely high noise floor of about -50 dBm. (The noise floor at my home office is about -88 dBm, which is moderately quiet.)

Reception of channel 2 became such a problem for KSNV that they eventually relocated to UHF channel 22, where they can easily be picked up with an indoor antenna. But other stations won’t be as fortunate, as the spectrum will be fully packed after this year with no place to move for a ‘do-over’ if reception is a problem.

When the DTV transition happened in June of 2009, three stations in Pennsylvania, New York, and Connecticut had to move to channel 6. It became apparent very quickly that DTV converter boxes weren’t selective enough to reject interference from nearby high-power FM broadcast stations. So WPVI in Philadelphia and WRGB in Schenectady applied for and got permission to double their transmitter power in hopes of fixing the problem.

WPVI’s signal on channel 6 is having a hard time up against the many Philly-area FM stations just higher in frequency.

You can see how much of a challenge this downward move will present to people using indoor antennas. Figure 1 shows how WPVI’s 8VSB carrier looked when I tested the Antennas Direct ClearStream Eclipse loop antenna with an amplifier, while Figure 2 shows channels 9 and 12 with the same rig – but a much lower noise floor. Note the strong FM stations immediately to the right of WPVI, a potential source of interference and receiver overload that would not be an issue on high-band VHF and UHF channels.

This view of WBPH-9 and WHYY-12 shows both carriers standing tall above the noise floor (about -85 dBm) and easy to receive.

Figure 3 shows a bunch of UHF channels received the same way – the Eclipse has some resonance at these frequencies as it is close to a full-wave loop antenna, so indoor reception is relatively easy.

Pulling in UHF TV stations is a much easier task for a small indoor antennas like the Eclipse. A low noise floor (-87 dBm) doesn’t hurt, either.

I have two pretty sophisticated rooftop antenna systems (one on a rotator) and I have trouble picking up KJWP-TV in Philadelphia on channel 2 – the signal breaks up frequently and there’s lots of broadband noise showing on my spectrum analyzer when I point the antenna in that direction. There’s also a station on channel 4 (WACP) that pops in from time to time, although in the other direction toward New York City.

If a station you like to watch has to relocate to the low-rent district, you may need to spring for a better antenna, and it might be larger than some of the indoor models you’re used to seeing. If you are 20 or more miles away from the transmitter, you can forget those small picture frame or box-shaped models – they won’t work.

You might even have to (“gasp!) go back to using a pair of rabbit ears. Yes, they still make these; I found a pair in Best Buy the other day for about $15. Or it might be time to consider an outside antenna, and even that will have to be larger.

I’ll have more news once the spectrum repack is done later this month, and the FCC usually provides a link to a listing of TV station channel assignments. If you live near a large city where most of the high-band and low UHF channels are Being used by major networks, you’re probably not going to see much in the way of musical channels.

But if you live in a market where all of the active channels are on UHF – say, like Syracuse, NY or Scranton/Wilkes-Barre, PA – don’t be surprised when you can’t pick up some of those stations in the future. They might have moved down the street…

 

 

 

USEFUL GADGETS: Three Antennas and a Preamplifier for Cord-Cutters

The cord-cutting landscape has changed considerably in the past twelve months, and it’s no longer a fad, but a growing trend as more and more consumers decide that they can get by just fine without expensive pay TV channel packages.

In fact, Comcast reported yesterday that they now have more subscribers for broadband service than for pay TV channels, which accords greater importance to Comcast’s failure to acquire Time Warner: The combined companies would have controlled broadband distribution to a disproportionate number of U.S. homes.

While Internet service is the key part of cord-cutting, free over-the-air television still pays an important part. Think of the Super Bowl, the NHL Stanley Cup and NBA championships, and the NCAA Final Four championship game.

But there’s also a lot of good programming on free TV right now. In recent months, my wife and I have used our Channel Master DVR+ and TiVo HD to time-shift and watch The Blacklist, American Crime, Brooklyn 9-9, The Good Wife, 60 Minutes, American Odyssey, CSI, Blackish, Saturday Night Live, and Mr. Selfridge (plus a host of one-time PBS programs).

Throw in some Netflix streaming (House of Cards) and there’s plenty to watch without Big Cable. So a balanced cord-cutting approach should incorporate both broadband and terrestrial broadcast TV.

To get the former, you need a fast Internet connection and a late-model Wi-Fi router. To get the latter, you only need some sort of antenna to connect to your television or receiver/DVR, like the Channel Master box, TiVo’s Roamio, Tablo, or Mohu’s new Channels product.

Blessed with a few days of nice weather, I decided to excavate my pile of review products and found three antennas patiently waiting for testing. The first was a rather odd-looking design from HD Frequency, called the CC Aerowave ($49 with 12’ cable from www.hdfrequency.com). It resembles a small window with a 75-ohm coaxial balun attached to the inner corners of two panes.

The second antenna came all the way from Australia and goes by the name HD Quad ($39.99 from www.hd-quad.com). It’s a flexible, transparent antenna with UHF collinear elements, not unlike many other antennas I’ve tested.

The last antenna is a bit larger and is a six-element VHF/UHF yagi, and comes from Channel Master. The StealthTenna 50 (CM3010HD, $29.00 from www.channelmaster.com) can be mounted indoors or outdoors. It’s small enough to sit in a closet or attic space, or even in a room – think of it as functional art.

I also found a new inline signal preamplifier from Antennas Direct. The Juice UHF/VHF Amplifier ($79.99 from www.antennasdirect.com) can be used inside or outside and provides about 18 dB of signal boost with a low noise figure, which is real handy in areas where TV reception can be problematic. (Successful digital TV reception is all about signal-to-noise ratio!)

The tried-and-true bowtie antenna under test. Note the high-tech antenna mount.

The tried-and-true bowtie antenna under test. Note the high-tech antenna mount.

The HD Quad under test.

The HD Quad under test.

The CC Aerowave under test.

The CC Aerowave under test.

Channel Master's StealthTenna 50 under test.

Channel Master’s StealthTenna 50 under test.

THE SET-UP

For this round of testing, I dusted off my tried-and-true UHF bowtie antenna, once available from Radio Shack but largely ignored by retailers today. (Seriously – how many of them want to sell a $5 TV product?)

I set the bowtie up on a folding table in my home office and attached it to a large cardboard box with masking tape. While that part of the test was decidedly low-tech, I then connected the antenna lead into a two-way splitter, with one leg going to a spectrum analyzer and the other going to a Hauppauge Aero-M USB tuner, connected to my Toshiba laptop.

This arrangement allowed me to see the actual waveform and signal strength of each TV station under test. I could then verify successful reception with the Aero-M, and to close the deal, look at the actual MPEG-2 video stream from each station using TS Reader. These three measurements gave me a very concise report on the performance of each antenna.

If you go back to my last round of testing in November of 2014, you’ll see that I used the same antenna position (different box, though!) and same test gear. The only possible differences in testing would come from the amount of foliage on nearby trees, as my house is partially blocked from the Philadelphia/Roxborough antenna towers over a20+ mile path. (In other words, an ideal site for indoor TV antenna testing!)

The Philadelphia TV market is unique in that it has two high-power, low-band VHF TV stations – KJWP (IND) on channel 2, and WPVI (ABC) on channel 6. There are only 40 or so low-band DTVs in operation nowadays as that part of the RF spectrum is susceptible to impulse noise and strange propagation enhancement. Antennas that work well from channels 2 through 6 (about 54 to 88 MHz) are also very large – a half-wavelength dipole for channel 6 needs to be about 68 inches long!

There’s also one high-band VHF operation on channel 12, WHYY (PBS). The rest of the Philly DTV stations are active on the UHF band, starting at channel 17 (WPHL) and ending at channel 42 (WTXF (FOX)). In addition, I can easily pick up three DTV stations from the Allentown area: WBPH-9, WLVT-39 (PBS), and WFMZ-46 (IND). There’s even a repeater for WTXF on channel 38 that shows up on my home antenna array, plus WNJT-43 in Trenton.

The performance of each antenna was verified with an AVCOM spectrum analyzer, Hauppauge Aero-M USB stick receiver, and TS Reader software.

The performance of each antenna was verified with an AVCOM spectrum analyzer, Hauppauge Aero-M USB stick receiver, and TS Reader software.

THE TESTS

I picked a handful of stations to verify reception: WPVI-6, WBPH-9, WHYY-12, WPHL-17, KYW-26 (CBS), WUVP-29 (UNI), WCAU-34 (NBC), WYBE-35 (IND), WLVT-39, WTXF-42, and WFMZ-46. Any of these antennas would be doing an outstanding job if they grabbed all of these stations, as their signal levels vary widely and there’s about 113 degrees directional offset between the Roxborough and Allentown antenna towers.

The first measurements were made with the bowtie, but unamplified and with the Juice amplifier connected. I then repeated these measurements with the HD Quad, CC Aerowave, and StealthTenna 50; again, unamplified and amplified. (I’ll have separate comments at the end of this article on the performance of the Juice amplifier.)

Perhaps the toughest signal to pull in is WPVI on channel 6. Two of the review antennas aren’t really designed for low-band VHF reception, but WPVI runs quite a bit of power and manages to get picked up by brute force on many antennas. (None of the test antennas could pull in KJWP-2 reliably). The rest of the stations aren’t quite as challenging to pull in.

Table 1. Here's how each antenna performed with 11 VHF/UHF  test channels.

Table 1. Here’s how each antenna performed with 11 VHF/UHF test channels.

Table 1 shows the results of my tests. Amplifiers do make a big difference, and helped the lowly bowtie antenna and StealthTenna 50 capture first place with 9 out of 11 stations received reliably (i.e. no drop-outs for at least a full minute). To be fair, the StealthTenna 50 is a much larger, directional antenna than the CC Aerowave and HD Quad, both of which should behave like dipoles with classic figure-8 patterns.

Table 2 ranks the antennas by performance. The bowtie by itself wound up in a three-way tie for second place with the amplified HD Quad and bare-bones StealthTenna 50, grabbing 8 out of 11 signals. Following behind was the amplified CC Aerowave, having received 7 out of 11 stations successfully and the bare-bones HD Quad with 6 out of 11 stations.

Table 2. And here's how each antenna/amplifier combination ranked after the tests.

Table 2. And here’s how each antenna/amplifier combination ranked after the tests.

 

The Aerowave was a puzzler. By itself, it only received one station – WFMZ on channel 46. I experimented with laying it flat and orienting it at right-angles to the Roxborough antenna farm to try and improve reception, and oddly enough, both of these alignments were more successful than simply positioning the antenna with its face in the correct compass heading. Lying flat, it picked up 4 of 11 stations successfully, while angled at 90 degrees, it grabbed 6 of 11.

The literature supplied with the Aerowave says you can “position the antenna in any desired location,” but based on my results, you may be futzing with it for a while to get the best reception – something I didn’t have any problems with when using the Mohu Leaf, Ultimate, and Winegard FlatWave antennas last November.

Just how much difference does an amplifier make? Here's a view of channel 2 through 6, as received by the bowtie antenna, unamplified. WPVI's signal on channel 6 is at the center of the screen.

Just how much difference does an amplifier make? Here’s a view of channel 2 through 6, as received by the bowtie antenna, unamplified. WPVI’s signal on channel 6 is at the center of the screen.

And here's the spectral view with the Juice amplifier inline. You can actually see KJWP's signal on channel 2 now (far left).

And here’s the spectral view with the Juice amplifier inline. You can actually see KJWP’s signal on channel 2 now (far left).

 

ADDING SOME JUICE

Antenna Direct’s Juice amplifier worked much better than expected. Its specifications call for 17.5 dB of gain on VHF channels and 19 dB of gain on UHF channels. (10 dB = 10 times the signal strength, with each 3 dB in gain doubling the previous signal level.) The amplifier’s noise figure was specified as below 2 dB in the VHF bands and below 3 dB in the UHF bands.

In my tests, the Juice boosted WPVI’s signal on channel 6 by about 15 dB and raised the noise floor from about -87 dBm to -85 dBm – or 2 dB, as the specifications claim. All amplifiers generate noise, and a good design will keep that to a minimum to avoid spurious signals and interference to desired signals. (Cheap amplifiers won’t!) Performance was comparable on channels 9, 12, and even 17, where I saw signal levels increase by about 18 dB.

At the high end of the UHF band, I saw an improvement of 20 dB with an increase in noise figure of about 2.5 dB, using WFMZ’s powerful signal on channel 46 for testing. That’s excellent performance for a UHF amplifier and rivals that of the Channel Master Titan-series mast-mounted amplifiers I’ve been using for years. (Titan 2 VHF/UHF 16 dB $65.00, Titan 2 VHF/UHF 30 dB $69, both available from www.channelmaster.com)

I don’t have any data on the Juice’s resistance to intermodulation signal distortion (or overloading from very strong in-band and adjacent-band signals), other than to say that the dozens of very strong FM radio carriers that also broadcast from Roxborough didn’t create any reception issues for me with channel 6 when the amplifier was inline.

Here's a spectral view of WBPH-9 and WHYY-12 with no amplification...

Here’s a spectral view of WBPH-9 and WHYY-12 with no amplification…

And here are both channels after turning on

And here are both channels after turning on “the Juice.”

 

Here is a view of the UHF TV spectrum from channel 17 to channel 46, as received by the Aerowave with the Juice amplifier. (I could only pick up one signal without amplification.)

Here is a view of the UHF TV spectrum from channel 17 to channel 46, as received by the Aerowave with the Juice amplifier. (I could only pick up one signal without amplification.) Many of the TV signal waveforms are quite distorted, which makes the job of the adaptive equalizers that much harder.

Here's the same view of the UHF TV spectrum, this time received by the HD Quad equipped with the Juice amplifier.

Here’s the same view of the UHF TV spectrum, this time received by the HD Quad equipped with the Juice amplifier. Note that the TV signal waveforms are somewhat cleaner with less multipath distortion.

One more look at the UHF TV spectrum, this time through the elements on Channel Master's StealthTenna 50 and Juice amplifier.

One more look at the UHF TV spectrum, this time through the elements on Channel Master’s StealthTenna 50 and Juice amplifier. Most received channels are very clean with little multipath distortion.

Finally, the same UHF TV spectrum, this time as received by the lowly bowtie, again with

Finally, the same UHF TV spectrum, this time as received by the lowly bowtie, again with “Juice.” Amazing how well such a simple antenna works, isn’t it? That big spike on the far right is WFMZ-46, whose operating frequency is close to resonance with the half-wave loop created by the bowtie antenna. Hence, the very strong signal. (At one time, channel 46 was near the middle of the UHF band, believe it or not!)

CONCLUSIONS

It is amazing how little antenna you need to achieve indoor TV reception. My location is sub-optimal in this regard, given my distance to Roxborough and the number of obstructions in my path.

Yet, with just a $5 bowtie antenna, I was able to receive eight TV stations reliably (5 from Philadelphia and 3 from Allentown), including all major networks (CBS, NBC, ABC, Fox, and PBS). Adding the Juice amplifier brought in one more station, and probably fiddling with the bowtie position would have captured the remaining two on my list.

Channel Master’s StealthTenna 50 isn’t exactly small, but you can put it in tight locations indoors for reception, such as a townhouse attic. You can even install it on top of a shelf, or in a closet, and with an amplifier, it will do an excellent job – just use one of the many TV reception Web sites (TVFool.com is the best) to determine the compass heading and where to aim your antenna.

The HD Quad behaves like many other collinear antenna designs I’ve tested. It’s transparent, so you can hang it in a window, and it is a better performer on UHF channels than on VHF. Add an amplifier to it and you may grab a few more channels. One bonus – you can roll it up and take it with you on trips, as I often do. Hook it up to a USB tuner stick and you can watch local HDTV on your computer in hotel rooms.

The CC Aerowave was, to put it mildly, a disappointment. I even tried moving it to different locations, using the spectrum analyzer to peak the signal and see if I could improve those reception numbers. No dice! Some signals that wouldn’t come in at all were now just intermittent with frequent dropouts and frozen images. Adding the Juice amplifier didn’t help much, so I can’t recommend this antenna.

Finally, Antennas Direct’s Juice amplifier is a solid performer and delivers the goods. A noise figure approaching 2 dB in the UHF TV band is excellent performance for the price. There is a puzzler, though – although this amplifier is obviously weatherized, it doesn’t come with a mounting bracket for installation on a mast, which is the best place to out it to overcome signal loss and noise in the antenna downlead. Something for the AD folks to figure out…

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. )