Emergency TV Test

On Feb 07, 2020 we had a severe weather event which brought lightning storms and five EF1 tornadoes to my home state of Maryland and all close to where I live. We usually get only about three EF1s a year.

Later that afternoon into evening, I decided to charge a number of things that needed recharging. While charging our portable TV I decided to see if I could get any TV stations with just a living room set-up – no big antenna. In our area, ever since the moved to digital( HDTV), we have had to use roof or attic antennas. Even those do not guarantee good reception 100% of the time. Rain, snow, and even high winds can make watching Over-The-Air (OTA) TV impossible thanks to the FCC’s lower power limits for DTV.

I first attempted to receive stations with an extendable single element antenna. I was only able to pick up Channel 2 from Baltimore, and even that was not worth watching due to the station constantly dropping out.

I then went into my stash of small antennas and found a bowtie antenna. I attached it to the telescoping antenna and placed it on a trunk and held up by a candle lamp.

Photo 1: Living Room Set-Up

I placed it near a south-facing window, rotated it a bit, and was able to get channels 2, 13, and a few others. All of these were quite good, and I watched the weather news on channel 13. Note, the rain had stopped and the afternoon, while still a bit windy, was otherwise clear.

 

Photo 2: Channel 13 the next day test

That same afternoon, I came across an ad for a TV antenna. The antenna was called a “Clear TV” indoor TV antenna. Going to the web site, I found the descriptions, three of which I wanted to comment on, so I’ll list them here:

“Digital HD Indoor Antenna Works Just Like Your Old Antenna”
“4K Ultra HD TV Antenna Plugs into Any TV”
“Aerial Dipole & Breakthrough Copper Web Tech for the Clearest Reception”

“Digital HD Indoor Antenna Works Just Like Your Old Antenna” – This is because it is just like the old rabbit-ears antennas supplied with many older NTSC TVs.

Rabbit-Ear antennas are simply two telescoping antennas basically set up as a dipole but the angle between them can also be changed just as the length of each antenna can be changed.

Note 1: NTSC, is named after the National Television System Committee, and is the analog television color system that was introduced in North America in 1954.

Note 2: The DTV transmission system is referred to as ATSC (Advanced Television Standards Committee)

“4K Ultra HD TV Antenna Plugs into Any TV” – as long as it has a 75 Ohm F-Connector input, as all newer TVs do. But, the reason I question this statement is because 4K UHD (Ultra High Definition) has nothing to do with what an antenna receives. An antenna receives various frequencies/wavelengths of the electromagnetic spectrum. Put a bit more simply, antennas are designed to receive the frequencies, or wavelengths, your TV’s receiver can receive. The term 4K tells us that the information (the picture in this case) that is carried on these frequencies is UHD. The way in which this information is carried by the frequencies does not in any way influence the antenna design. The only thing that influences the antenna design is the frequencies it must receive.

Again, the modulation used to impart the information on these frequencies is unimportant to the design of an antenna. So, this means that there is nothing special about an antenna that receives the frequencies that carry the UHD information. The antenna receives the frequencies, and then the receiver and demodulator circuits inside the TV get the UHD information off the frequencies. An antenna receives the TV frequencies, and the circuits inside the TV get the U/HD and sound information off the frequencies. It demodulates the information, picture and sound, and then sends it to the screen and speakers.

“Aerial Dipole & Breakthrough Copper Web Tech for the Clearest Reception” – Yes, this design is a basic dipole, but rabbit ears not only change the length of the dipole but also the angle between the two sides of the dipole. The length changes which frequencies/channels are best picked up by the antenna. The angle and direction of the dipole elements can change the direction best received as well as the polarization of the signal best received.

The copper web technology is, in my opinion, simply advertising hype. The only place the copper web can be is inside that small box underneath the two dipole elements. and it is vertically oriented, which, from my understanding of antenna design, will not change the dipole receiving pattern by much if at all. The dipole elements can change length, direction, and angle, so I think any modeling of any effect this may have would be very extensive and time-consuming to determine. It is simply not worth the time and effort for such an inexpensive antenna to bother with.

Usually a web of some reflecting material, like copper, is used behind the antenna to reflect the waves back into the antenna and also to block interference coming from behind the antenna. Sometimes this web, or reflecting surface, is flat sometimes it is curved. I’d like to see their design and any supporting data to support their claims.

Last, “Clearest Reception” has nothing to do with the antenna; it has only to do with the signal level. The antenna does have a bit to do with the signal level, but if you are too far away, the signal will not be able to be decoded and no picture will be displayed.

If the signal level is sufficient for the receiver in the TV to decode, then the picture will be whatever is on the frequencies received. The signal level received is determined by the antenna, but it is also dependent on the strength of the transmitted signal, the distance from your antenna to the TV transmitter’s antenna, and all the stuff between your antenna and the transmitting antenna, as well as any interference by other signals received by your antenna.

 

Photo 3: Clear TV Model: Premium HD Mini

I’m not tempted to buy one of these, even with their buy-one-get-one-free offer. For one thing, I believe almost anyone can build something at home which will work every bit as well, if not better, than this antenna design, and for much less (almost nothing, in fact, if you already have the materials).

Since one has to pay ~$8 for shipping for each antenna, the free antenna is not all that free. Also, while you can return the antenna for a full refund, they do not include the shipping fees as part of the refund, so you have to pay for shipping to you and back to them.

I estimate that the box size is about: 2″ X 4″ X 0.5″ but I’ll look into that further in the next article.

I called and spoke with a person who tried to help answer my more technical questions, but it turned out that she had simply gone to the main company’s web site and found a brochure, which she then gave me the URL to that information. I have not found anyone to talk to who was actually in on the design of the antenna.

Here’s the information on this small dipole (rabbit-ears) antenna:

TECHNICAL DATA:
Frequency range:
VHF 174-230MHz, dipole ~ 2’10.7” to 2’ 1.7”
UHF 470-862MHz , dipole ~1’ 0.5” to 6.9”
Gain: 0~3dBi
Receiving Range: FM/VHF/UHF (FM is from 88 – 108 MHz dipole ~5’ 7” to 4’ 6.7”)
Impedance: 75 Ohms

In my next article, I will test a simple dipole, like the Clear TV antenna, against a homebrew bowtie antenna for receiving in my area, which should give us some idea of how well the Clear TV antenna performs compared to a simple-to-build TV antenna. I may even try to have a reflector like their copper mesh. A simple piece of aluminum foil cut to the same dimensions should do the same thing.

One more very minor piece of advice. No matter which antenna you use – a bowtie, rabbit ears, or some other small antenna – don’t place it behind your TV as shown on the Clear TV web site. This is the second-worst place because the TV electronics will interfere with any signals coming from the direction of the TV. The worse place to put the antenna is in front of the TV. This is because – like putting it behind the TV – the TV will interfere with any TV signals coming from the direction of the TV and, even worse, the antenna may block the user’s viewing pleasure. ?

Until Next time, Happy OTA TV watching!

All my blog articles are listed at: Karras’ Corner
http://blog.solidsignal.com/author/philk/
or
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