June/July 1940 National Radio News
of Contents] These articles are scanned and OCRed from old editions of the
National Radio News magazine. Here is a list of the
National Radio News articles I have already posted. All copyrights are hereby acknowledged.
Both funny and ridiculous
I thought as I read this article from a 1940 edition of National Radio News
where author Julius Aceves, a consulting radio engineer, makes the case for
not buying a newfangled, cheap radio that is supplied with a built-in antenna
when using a good old-fashioned outdoor antenna is the better option. It's not
that he doesn't have a valid point about the larger, obstruction-free outdoor
antenna providing superior signal strength and a greater signal-to-noise ratio;
it's that part of his argument is that in doing so you are denying the outdoor
radio antenna companies revenue. That mindset is akin to telling people they
should not buy notebook computers because in doing so you are denying computer
monitor and keyboard manufacturers their rightful sales volumes. He does, to
finally admit that there are "a few well-engineered
antenna kits" that are worth consideration if
you insist on taking food from the mouths
of antenna salesmen's children. As you probably know, it is rare to find a radio
today that does not have at least an internal AM antenna, often with no provision
for any type of external antenna connection. Most radios do offer a connection
point for an external FM antenna, however. A common method for effecting a cheap
FM antenna is to use the AC line cord as the antenna or, in the case of a portable
device like a smartphone, the ear bud wires from the antenna. Higher end models,
like my nifty
Tesslor R601S vacuum tube radio and my
Sangean WR-2, are supplied with internal antennas and connection
points for both AM and FM external antennas.
Advantages of Outdoor Antennas
Loops and indoor antennas have a definite place in the radio industry, but
a good outdoor antenna system is still tops when it comes to picking up distant
stations and keeping noise interference at an absolute minimum.
By Julius G. Aceves,
Amy, Aceves & King, Inc., Consulting Radio Engineers,
11 West 42nd St., New York, N. Y.
To one who has specialized for years in signal pick-up and interference elimination
technique, the recent attempts to do away with outdoor antennas are something
truly to cry about. Indeed, we are going backwards in our radio reception when
we get away from noise-reducing outdoor antennas in favor of loops and built-in
antennas for operation of moderate-priced and high-fidelity receivers. Convenient
and cheap as these antenna substitutes may be, they cannot and do not take the
place of the noise-reducing outdoor antenna, in providing for optimum performance
from a broadcast receiver. To prove that point is the purpose of the following
Also, from your standpoint as a Radiotrician this antenna-substitute trend
is far more than an academic question. It means dollars and cents out of your
pocket. For every time a set with loop or indoor antenna is sold, it means the
elimination of one more revenue-producer for the service trade. Antenna installations,
check-up and repair jobs are "gone with the wind" when antenna-less sets sweep
into popularity. Hence it's your concern, too, that the public be educated with
regard to the superior results which an outdoor antenna will always provide.
First, let's be perfectly frank about this whole matter. We'll concede at
the start that there is a definite place for the loop and built-in antenna.
Technically, the self-contained signal interceptor is perfectly legitimate for
portable sets. Also for tiny midgets that may be transported from room to room,
or that may be used in temporary quarters such as hotel room, school dormitory
Economically, in the face of midgets selling for $10 or less, the built-in
signal interceptor is again legitimate and even essential. No midget-set buyer
is going to spend a few dollars extra for an outdoor antenna, especially in
metropolitan areas close to powerful broadcast stations. Meanwhile, the limited
tone quality of these bargain-basement sets is such that one or two more handicaps
don't mean much, anyway.
Turning to better-grade radio sets, the self-contained interceptor is quite
another matter. Technically, the loop, built-in antenna or indoor antenna decidedly
handicaps set performance, as we shall presently prove. Economically, such a
set owner can well afford another few dollars if much superior results can be
obtained. So our interest is primarily in better-grade sets.
Now just a few elementary principles to refresh our memories and pave the
way for the reasoning to follow:
Fig. 1. Signal strength of tuned and untuned antenna
compared with a tuned loop.
Fig. 2. Comparison of performance of a noise-reducing
system with conventional antenna of same dimensions.
Radio waves have two components: electrostatic and electromagnetic. The device
picking up these waves may be actuated mainly by one or the other. Accordingly,
we have a collector of the open antenna or the shielded loop type.
The loop being a directional device, we can get maxima or minima by rotating
it in space. Thus, we can differentiate between two waves coming from different
directions. One wave may be that of a desired station; the other, a source of
interference. Better reception is obtained by turning the loop against the interference
source rather than for maximum signal reception. By shielding the loop, we practically
eliminate the electrostatic component and receive by means of the electromagnetic,
with maximum directional effect.
All of this sounds ideal. In localities where radiated interference is very
low and signal strength fair, the loop may be satisfactory at least in the broadcast
band. Foreign stations in the short-wave bands from 49 meters down to 16, cannot
be received with the same broadcast loop because of tuning-range difficulties.
Also, since the field strength of overseas stations is usually low, they cannot
be heard well even on a special short-wave loop under normal circumstances.
The same applies to ultra-high-frequency reception. Television reception is
out of the question. For signal pick-up, the loop is no better than an in-door
antenna. A shielded loop, however, gives better discrimination against noise
than an in-door antenna.
Most horn are none too happily situated with regard to low interference level
and high signal level. The radio set may be surrounded by inductive interference
or so-called "man-made static." There are motors with sparking brushes, interrupters
in thermostatic controls, electric bells, dial telephones, contactors for elevators,
and so on. There may be that arch terror of radio noises, diathermy apparatus.
Outside, there may be neon or other gaseous-tube type electric signs, or even
incandescent lamp signs with motor-driven contactors. A trolley line nearby
doesn't help matters. Neither does a high-tension transmission line with leaky
insulators or transformers.
How can the loop take care of this situation? If oriented for a minimum (or
even a "null") for one source, it is not going to help noises from other directions.
Moreover, it is well known that the induced voltage in a loop is very weak in
comparison with the electromotive force from an open antenna, even of the indoor
type. Therefore, when receiving from stations other than locals, we are going
to get tube noises; unless the receiver is extremely sensitive, the automatic
volume control cannot take care of fading.
What to do? Can a well-designed outdoor antenna system really reduce background
noises and increase signal strength in a typically poor radio location? The
answer is decidedly yes.
You may be skeptical. Other servicemen have become skeptical. During the
last half-dozen years, the market has been flooded with so-called "noiseless
antenna kits." Fantastic claims of noise-reducing properties have been made
without proper foundation. It is a safe guess to say that more than 75% of such
kits failed to reduce noise as compared with ordinary antenna wire, in any worth
while degree to justify the claims. Frankly speaking, there have been many "phonies"
marketed, which have given a big shiny black eye to this antenna-kit business.
Nevertheless, there are a few well-engineered antenna kits - and master antenna
systems which are the product of years of study and specialization. These kits
really do the job. All they require, from an installation standpoint, is to
have the actual pick-up structure (be it a doublet, "T", or vertical rod of
proper height) in a noise-free location, equipped with suitable couplers and
transmission line and a good quiet ground, in order to effect an amazingly high
degree of interference reduction. This is done in a two-fold manner:
1. Neutralizing the interference pick-up from the line connecting the antenna
proper with the radio receiver, and preventing the passage of spurious currents
from the power line into the input circuit of the radio receiver.
2. Increasing the signal strength by maximum pick-up of the intercepted radio
In order to illustrate these principles, measurements were made of signal
and interference pick-up on typical loops and antennas with and without noise-reducing
equipment. The results are shown in graphical form as follows:
Figure 1 shows a typical instance of relative signal levels from a tuned
loop vs. an outdoor antenna of the tuned and untuned types. From these graphs,
the superiority of the antenna over the loop for signal strength alone is apparent.
Curves A, Band C in Fig. 2 represent: A, the signal-level difference;
B, the noise-level difference; C, the signal-to-noise logarithmic ratio (curve
A minus curve B), for a certain noise-reducing antenna kit on the market, as
compared to an ordinary outdoor antenna and downlead of same dimensions. Curve
C gives the resultant noise reduction for a given signal loudness, and represents
the improvement in reception, which is as high as 40 decibels in some instances.
Do you realize what this means? Well, it corresponds approximately to the
adding or suppressing of a stage of audio amplification. In other words, it
corresponds to raising or lowering the volume of an orchestra from piano to
forte, or in piano playing, from mezzoforte to fortissimo. This represents the
effect of an increase of about 100 times in signal voltage, as a reduction in
the noise has the same effect as such a signal increase.
How would you like to soften the interference in your radio receiver from
an annoying forte to a tolerable piano level when listening to the New York
Philharmonic Symphony on a Sunday afternoon, if you are a music lover? This
would certainly justify the additional expense of a noise-reducing antenna.
That is the argument to pass on to your customers.
And so in conclusion: There's no substitute for the properly designed, perfected,
noise-reducing antenna system, correctly installed. You can readily demonstrate
the practical gain in signal strength and reduction of background noise by installing
such a system in your own home or shop, and having set-owners come to hear the
results for themselves. You can safely install such a system on a money-back-if-not-satisfied
basis, for it does prove itself. In this manner, you can show that antenna-less
receivers, threatening to become universal, cannot give the best possible reception.
Remember also that antenna-less receivers cut down service revenue.
Editor's Note: The foregoing article represents the views of the writer,
a well-known antenna engineer, and was prepared especially by him for the National
Most of the loop-equipped sets have provisions for outdoor aerials. By connecting
a good aerial to such a set when it is tuned to a distant station, you can demonstrate
that signal level noticeably rises and noise goes down. Even holding a finger
on the antenna post of many of these sets, while tuned to a distant station,
will sometimes prove effective as a demonstration of the need for a good aerial
when DX reception is desired. In a noisy location, only a noise-reducing antenna
of good quality should be considered.
Although the author made no mention of a specific antenna system in giving
performance curves, we presume he is referring to one of the types manufactured
under patents held by Amy, Aceves & King. The antenna kits sold by the Technical
Appliance Corp., 17 East 16th Street, New York City, using the trade name Taco,
are so licensed. Information on these kits may be obtained by writing directly
to the manufacturer.
Undoubtedly, there are other concerns making kits that will also perform
satisfactorily in giving a good signal-to-noise ratio. A trial of several types
should be made if possible, at your shop, to determine the best type for your
Posted April 22, 2014