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April 1968 Radio-Electronics
 [Table of Contents]
Wax nostalgic about and learn from the history of early electronics.
See articles from Radio-Electronics,
published 1930-1988. All copyrights hereby acknowledged.
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The April 1968 issue of
Radio-Electronics magazine had a series of articles on the latest in antenna
technology. It included "TV/FM Antennas
Are Getting Bigger and Better," "Antenna Rotators," this "1968 Crop
of CB, Ham and Communications Antennas," and a couple others, including a
build-it-yourself design for UHF television. UHF was a big deal in the day, and
was supposed to be the savior of over-the-air broadcast TV, but cable TV came on
the scene and cut the legs out from under it, so to speak. As noted by author
Noel Penn, it is interesting that the FCC often does not give an
EIRP* (effective
isotropic radiated power) number for radiated power, only a maximum power level
into the antenna. FCC Part 97.313(c)
Transmitter power standards does specify EIRP numbers for a few sub-bands, but
otherwise uses PEP (peak envelope power). The majority of radio users are
technology users with no knowledge of or interest in the science behind the
technology. Manufacturers generally make equipment that performs at least
acceptably - albeit with some annoyances - as long as all the components are
connected properly. Nowadays with the vast majority of personal communications
(radio, TV, and Internet) being accomplished via cellphones, very few people
will ever need to mess with cables or antennas. Wireless charging eliminates that
last remaining physical connection.
*Sometimes ERP is used which is reference to a standard half-wave dipole with
a gain of 1.64 dB.
1968 Crop of CB, Ham and Communications Antennas
Cushcraft CB-114D 8-element dual-beam base station
CB antenna provides 12 dB gain. Front-to-back ratio is 25 dB and VSWR is 1.3 to
1. The dual-beam can be used with any heavy-duty rotator. It has a turning radius
of 12 feet.
Hy-Gain CLR2 base station CB antenna has electrically
extended 5/8 wavelength radiator. Effective output power is 6.6 watts and VSWR is
less than 1.5 to 1. The CLR2 will survive up to 80-mph winds. It provides an omnidirectional
pattern.
Antenna Specialists MC27 is an omni-directional
ground-plane CB base antenna. Features include 108" solid aluminum heat-treated
radials, bent at base clamp to proper angle for 50- ohm match. Antenna has omni-directional
pattern.
By Noel Penn
When you think about home TV and FM antennas, you are concerned only with reception.
However, in CB, ham or mobile antenna installations the most concern is for transmission.
While transmitter power is limited by the FCC, antenna gain is not. Since an
increase in antenna gain is just as effective as an increase in transmitter power,
antenna selection is very important.
Cush Craft Squalo is a full-wave. horizontally-polarized,
omnidirectional ham antenna. These antennas can easily be stacked vertically to
form a complete 5-band "Squalotree" covering the 6-through 40-meter amateur bands.
Six-meter Squalos are packaged with suction cup for car mounting, plus a horizontal
center support for mast or tower mounting. The Squalo can even be mounted outside
a window.
Cush Craft Colinear arrays are well suited to
general amateur vhf operation and for amateur TV communications. The 16-element
antenna provides a direct match to 300-ohm line, or can be matched to
75-ohm coaxial cable with a balun. Matching stubs are available to match 450-, 200-,
75- or 52-ohm cable directly. Colinear arrays can be stacked for even more gain.
Antenna efficiency can be improved in three ways:
1. Add elements that increase directivity. Base-station antennas, for example,
can be made highly directional and rotated to aim at mobile units.
2. Mount the antenna at an optimum height. Follow the antenna manufacturers'
instructions. For local contacts, consider line-of-sight obstructions.
3. All antennas in a communications system should be polarized in the same way;
either all horizontal or all vertical. Vertical antennas have vertical polarization.
Single-element verticals tend to be omnidirectional and put out signals in a horizontal
direction, with little or no signal going straight up or straight down.
4. Improve match. You get maximum transfer of power only when the transmitter,
the antenna and the transmission line between them are properly matched. The amount
of signal put out by the transmitter but not radiated by the antenna is reflected
back and forth in the cable and sets up standing waves. Thus, the degree of match
is expressed in terms of VSWR (voltage standing-wave ratio). A perfect match would
be a VSWR of 1:1, and 1.5:1 is considered the maximum allowable for a good antenna
installation.
The partial selection of antennas shown here can only suggest the vast number
of various types available.
Today's CB'ers and hams have a tremendous variety of antennas from which to choose.
Some antennas can be used for a number of different applications. Many are easily
alterable or tunable to frequency. There are antennas for homes, offices, cars,
boats and airplanes, with electrical characteristics and mechanical features to
suit each. One manufacturer (Mosley) even offers a line of do-it-yourself antenna
kits for CB'ers who want to build their own.
 To the right
from left to right:
Mosley Lancer 23 is a mobile antenna designed for the CB'er
who aspires to be a ham or the ham who works the CB channels. For the CB'er the
Lancer 23 is equipped with a 10·meter coil. For the amateur, interchangeable coils
for 10 to 75 meters are available. The antennas in-corporate a peaking provision
for adjustment to any CB channel.
Hy-Gain Hellcat 1 mobile CB antenna has a low-profile look,
an etched copper, high-efficiency loading coil in the base, and a spring mounted
17-7 PH stainless steel whip. A new "Claw" mounting device enables antenna to be
quickly installed.
Antenna Specialists ASM-1 is a 10-foot CB Marine antenna made
of white fiber glass. It has a center-loaded fiber glass whip and chrome-plated
brass and stainless-steel fittings. It includes a mounting and lay down kit made
of Cycolac, 15' of RG·59/U cable and a connector.
Mosley "Channel Cat" is a CB marine antenna made of stainless
steel. Designed to eliminate the need for radials or other difficult to install
ground systems. it is effective even on wood and fiberglass boats. The antenna is
salt water protected. Loading is through a waterproof coil in the antenna center.
Posted June 15, 2023
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