There was a time that selecting a television antenna was as important to the
quality of life as buying the right smartphone is today. There were probably as
many choices in antennas then as there are phones now. You might think, especially
if you are not an amateur or military radio operator, that nobody worries about
antennas anymore, but as I've written before there is a slight resurgence in people
installing the old fashioned multi-element antennas for receiving local television
and radio stations. The market's not huge, but seems to be keeping companies like
Channel Master in business. Incidentally, in contrast to my aforementioned comment,
dig the opening sentence of the article: "Virtually no one in this day and age goes
about discussing the reception quality of his telephone."
Antenna Performance Key to Good Color Reception
May 1969 Vol. 36 - Issue 2
Technical Editor R. A. Humphreys
A National Pastime
Virtually no one in this day and age goes about discussing the reception quality
of his telephone. The telephone works, so he takes it for granted. Yet every day
millions of people discuss their television reception. "How's your picture?" is
a nationally discussed question. Obviously, the person who inquires is seeking to
compare his "picture" with that of someone else's. He is doing this because in his
mind he is doubtful about the quality of his own reception. He has good reason to
be doubtful, for he and millions of others are the victims of sub-standard reception.
This is especially true of color.
"My color set is no good," is the usual explanation advanced by the householder
to explain away a poor picture, and he believes it.
Ingredients of a Good Color Picture
Let's examine the facts. The vast majority of popular color receivers manufactured
today are perfectly capable of delivering high-quality color pictures. To prove
this, a visit to any of the plants where the sets are made will afford you an opportunity
to see thousands of color receivers "lit up like Christmas trees" as they come through
final test. How then is it possible that these sets give good color results at the
factory and yet perform poorly in the living room? The answer is simple: at the
factory they are being fed with the proper color signal, and in the home of the
user, they are not. There is no mystery or magic involved in good color reception.
besides the presence of a well functioning color receiver, you need only these three
additional ingredients: a reasonable level of interference-free signal, a well designed
color antenna, and a proper transmission line. Put them all together and you have
excellent color every time. Leave one out and there goes the color picture!
The level of available signal at the receiving site is usually a matter over
which you have limited control. However, the choice of which antenna to use is far
more broad. Everyone and his brother has some sort of antenna that they are pushing.
In far too many cases the decision is made to sue the cheapest and most readily
available color antenna on the theory that, "what's the difference all antennas
are pretty much the same." This simply is not true, and if the installer wished
to avoid customer complaints about picture quality, he should not make this assumption.
Many of the antennas on the market today are poorly suited to the task of providing
quality color reception consistently over a long period of time.
Figure 1 - Variety of Model "Sizes"; Trend of Gain to Increase
Figure 2 - Channel Response
Figure 3 - Directivity of Sylvania Model 32 VU Fringe Area Antenna
The 'Lens" of the Color Receiver
What then is a good color antenna? It is, simply stated, a device which has been
designed to process each television channel individually in the most linear possible
fashion and for the longest possible time. Does this mean that antenna gain is no
longer important? No, the forward gain of the antenna is just as important for color
as it is for black and white TV. However, since the black and white transmission
utilizes only a segment of the bandwidth for each six-MHz television channel, abrupt
variations in gain across a channel and from channel to channel could be tolerated.
On the other hand, color transmission utilizes a considerable portion of each
six-MHz television channel, and its proper reception dictates that the color antenna
present a relatively flat and linear response to the entire transmission of each
channel to permit all of the transmission to reach the receiver. Failure of the
antenna to do this causes the antenna to act effectively as a filter, which distorts
much of the color information before it ever reaches the receiver. Further, to minimize
color smear and other forms of distortion, the antenna should respond relatively
little to unwanted signals. Thus, it may truly be said that the color antenna is
the "lens" of the color receiver. Obviously, no one should use a poorly designed
color antenna as the "lens" for a color set and expect optimum performance.
The Rugged Elements
Therefore, to develop the Sylvania line of color antennas, we were faced with
the problem of designing a set of broadband, high-gain, directional, and effectively
linear devices. But that's just the beginning. As a primary goal, our antennas would
have to continue delivering their designed performance for three years, four years,
and longer. While we were at it, we took particular care to include the FM spectrum
as well. As a necessary measure to meet these goals, these antennas would be fabricated
from materials substantially superior to those in general use today by other rooftop
antenna makers. Mechanical design would also be of primary importance. We did this
not only to achieve a superior mechanical product, but particularly to insure the
electrical integrity of the antenna, including both relative parts alignment and
continuity, for the longest possible time. Remember, an antenna is truly an electrical
circuit. The longer each of the antenna parts resists the elements and corrosion,
the longer the antenna will permit the receiver to deliver good color pictures.
Simply stated fine electrical design means little if the mechanical design is flimsy.
The instant an element is bent out of alignment or snapped off - there goes electrical
As an example of this, when our field experience clearly indicated the need for
an antenna which could cope with the high incidence of salt and toxic corrosion
so prevalent in many residential areas of the nation, salt corrosion tests were
conducted. The results not only indicated a need for a completely aluminum antenna,
but also one on which all surfaces of all parts, both inside and out, were treated
with the immersion alodine process before assembly. This same process is now carried
out with every Sylvania production antenna.
The Cost Factor and Long Life
For some reason many service and installation men are reluctant to sell quality
antenna installations, perhaps in the mistaken notion that the customer has "shot
his roll" when he purchased his color receiver. To the average householder, the
entire matter of obtaining a color picture in his living room is indeed a mystery.
Bluntly, he doesn't know what he needs, and it's up to the service man to intelligently
Your customer wants good color pictures. This is why he is constantly comparing
his result with others. He is also willing to pay to get it, as evidenced by the
thousands of householders who subscribe to community antenna systems to obtain better
pictures. It logically follows that informed customers are also willing to pay for
quality antenna installations - they are less expensive in the long run.
An antenna's initial performance is one thing - but what happens to performance
after the antenna has been on the end of a mast for a year or two? The key to all
of this is durability - durability through the materials used, through mechanical
design, and through construction details.
The centerfold of this article examines these and other performance criteria
in detail, and the degree to which the Sylvania line of color antennas meets them.
Ten Requirements of Good Color Antennas
Figure 4 - Driven Elements / Snap - Lock Joints / Double Boom
Form Continuous Transmission Path
Figure 5 - Overall Rugged Construction; Parts of High Quality
Aluminum and Plastic
Figure 6 - Full Alodine Protection of All Aluminum Internal and
1. The antenna must have sufficient gain for the area in which it is installed.
This is sizing the antenna for the particular location where it will be used. By
sizing we mean selecting an antenna of such gain that the TV set will be provided
with enough signal to properly drive it. Suitable signal strength would range from
200 μV to 2000 μV. The Sylvania broad line of color antennas provides a model
for every location (Figure 1), from the near-suburban to the deep fringe areas.
The antennas provide more gain as frequency increases. This compensates for the
propagation and feed line losses which increase with frequency. Figure 1 indicates
the trend of the Sylvania line of antennas to show increasing gain with increasing
frequency. The gains shown correspond to antenna response at mid-low VHF band (channel
4), FM (88 MHz), mid-high VHF band (channel 10), and mid-UHF band (channel 50).
2. Ideally, antenna response should be essentially linear across the six-MHz
band of each channel. This assures that all of the transmitted video, color, and
audio information is faithfully introduced to the transmission line. Wide variations
in gain across a channel can destroy picture fidelity, particularly in a low-signal
area. For example, a droop in antenna gain towards the high end of a channel (Figure
2A) will result in loss of color performance. Sylvania antennas are designed for
a gain performance of ± one dB across each channel (Figure 2B).
3. The antenna should be directional, that is, signals appearing at the sides
and rear should be largely cancelled or suppressed. These unwanted signals, if not
greatly attenuated relative to the forward gain of the antenna, commonly appear
in the set as ghosts, reflections, co-channel interference, and noise. Any of these
can play havoc with a color picture. Figure 3 indicates the excellent front-to-back
ratio of one antenna of the Sylvania line. At the two typical frequencies (channels
11 and 47) shown, the rear 180-degree response of the antenna is less than 10 per
cent of the forward pickup. Notice the freedom of large, interference-producing
4. To cover all present TV channels allocated by the FCC, the antenna must be
receptive to VHF (54 to 88 MHz and 174 to 216 MHz) and UHF (470 to 890 MHz). It
is also highly desirable for the antenna to include FM (88 to 108 MHz). All antennas
of the Sylvania broad line were specifically designed to cover both the VHF and
FM bands. For areas in which UHF is present, Sylvania provides antenna models which
cover all bands (VHF, FM, and UHF).
5. Output impedance of the antenna should be matched to transmission line. Mismatch
between antenna and lead wire can cause color smear and cut down on efficiency of
the antenna. l! is vital that a well matched transmission line be used. Basically,
there are two impedances used in home receiving antennas: 300 ohm, and 75 ohm. A
75-ohm antenna is often effectively used in high noise areas and feeds directly
into 75-ohm coaxial cable which provides complete shielding. The Sylvania broad
line of color antennas is available in both 75 and 300-ohm impedances.
6. An antenna that has all of the previous electrical performance characteristics
is of little value unless electrical integrity of all elements to feed lines is
maintained over a long period of time. The antenna is an electrical circuit; therefore
if an element loses contact with the feed line, a part of the circuit is lost. Obviously,
when this happens the antenna no longer functions as designed. Wind, rain, ice,
and other environmental conditions combine to make this requirement a formidable
task for the antenna designer to achieve.
Sylvania achieves this electrical integrity in its antennas through use of the
double boom design, in which the booms themselves are the transmission lines. The
rectangular boom provides a large, flat surface for solid mechanical and electrical
contact with the positive-lock snap joints (Figure 4), which retain the driven elements.
Carefully-formed shoulders on the snap joints assure long-lived electrical contact
with the elements. This design makes the elements, effectively, electrically integral
with the double boom transmission line.
7. The antenna must be strong enough to withstand the strong winds and other
climatic influences encountered in its roof-top environment. Mechanical design is
a primary consideration in meeting this requirement. Features of the Sylvania antenna
design in this respect are:
• Double boom construction - much stronger than a single boom design (Figure
5). Booms connected and reinforced by sturdy bridge cross ties.
• One-half inch, seamless elements - a Sylvania exclusive. Being physically
stronger, the elements hold their alignment much longer. The greater surface area
provides a high Q. The absence of seams means better radial symmetry throughout
the length of the element-all factors which provide a more efficient electrical
• No braces required from boom to mast - permits mounting an antenna rotor
directly beneath the antenna. Rotor life is increased through elimination of a long
• End caps on ends of booms - prevent corrosion-causing water traps.
8. As an additional requirement for long antenna life, booms and elements should
be built of high quality aluminum tubing. Skimping here again means short antenna
life. All Sylvania antennas incorporate rectangular cross-section, seamless booms
of structural grade 3005-H-29 aluminum with 1-inch by 1-inch by 0.041-inch walls
(Figure 6). Elements are half-inch seamless aluminum with 0.0165-inch walls. High-strength,
injection molded plastic is used for all non-metal parts. Rivets, U-bolts, and all
other hardware are of heavy-duty, industrial grade.
9. The antenna should be protectively coated to resist the effects of salt and
other corrosive atmosphere. This coating should be applied to inner and outer surfaces.
All aluminum parts of Sylvania antennas are processed through a seven-bath, weather-resisting
alodine solution prior to assembly. This assures that all surfaces are completely
covered. The high-conductivity coating penetrates the metal surface to a nominal
depth of two-mils (Figure 6).
10. The antenna must be easy to install. There should be a minimum of loose parts
and subassemblies in the box, and installation instructions should be clear. To
ease the installer's job, Sylvania has incorporated these features into its broad
line of color antennas:
• Quick, set-up snap joints lock the elements into place in minutes.
• Major parts are preassembled.
• All hardware is in place.
Posted June 20, 2019