The Broadcast Antenna
01 Jan 1936-Vol. 24, Iss: 1, pp 11-35
TL;DR: In this article, the authors concluded that the conventional broadcast antenna supported by two towers, as used in the past, is definitely outmoded by the single vertical radiator, or, in special cases, by a combination of vertical radiators in a directional array.
Abstract: During the past several years, the trend in broadcast transmitting antennas has been towards the vertical radiator. The performance of these newer antennas has been subject to considerable theoretical discussion. This paper, however, emphasizes the actual field results obtained with tower radiators, and presents data on efficiency, base voltage, base loss, practical design considerations, and cost. It is concluded that the conventional broadcast antenna supported by two towers, as used in the past, is definitely outmoded by the single vertical radiator, or, in special cases, by a combination of vertical radiators in a directional array. Antennas used in the broadcast band only, 550 to 1500 kilocycles, are considered.
Citations
More filters
26 Jun 1989
TL;DR: In this article, an image plane version of the Corum element is used to surround an existing tower, and the resulting antenna will improve the sky-wave suppression in all cases, with a modest increase in ground wave.
Abstract: The authors present experimental verification of an improved directivity element (the Corum element) for controlling the elevation plane directivity of a vertical monopole element. The results suggest that, if an image plane version of the Corum element is used to surround an existing tower, the resulting antenna will improve the sky-wave suppression in all cases, with a modest increase in ground wave. While performing an antifade engineering study for a broadcast antenna at 530 kHz, the authors decided to run a study on a typical 1 kW GWEN (ground-wave emergency network) station (300 ft tower in the 160-190 kHz band). It was found that the Corum element makes a significant improvement in useful GWEN coverage. >
60 citations
TL;DR: In this paper, an asymmetric vertical dipole was proposed as an AM-broadcast station transmitting antenna, which uses the supporting guys as part of the radiating structure permitting an efficient radiation with a strong surface wave.
Abstract: An asymmetric vertical dipole is proposed as an MF AM-broadcast station transmitting antenna. This kind of vertical dipole antenna uses the supporting guys as part of the radiating structure permitting an efficient radiation with a strong surface wave. It produces less high-angle radiation compared to a classic buried-ground-plane monopole of similar height. Analysis data for near fields and power density of monopoles, elevated ground plane monopoles, and asymmetric vertical dipoles are presented graphically to explain why this last antenna can match the radiation efficiency of the classical monopole without a buried ground plane. Good agreement between calculation and measurements is achieved in all cases studied. >
8 citations
01 Nov 1948
TL;DR: In this paper, a new type of broadcast antenna is described which radiates very little energy over a wide, high angle, and the electrical height of the antenna is dependent upon the specific vertical pattern desired but is approximately 300°.
Abstract: A new type of broadcast antenna is described which radiates very little energy over a wide, high angle. The angle above which minimum energy is radiated can be varied electrically from 40° to 60°, thus permitting the fading wall to be adjusted for maximum primary service. The electrical height of the antenna is dependent upon the specific vertical pattern desired but is approximately 300°. The results of experiments with small model antennas are in good agreement with theory.
7 citations
TL;DR: Calculations were made to determine the theoretical nocturnal service area of a station using vertical arrays, and curves with maximum distortionless distance are given as a function of frequency and ground physical constants.
Abstract: The nocturnal service area, or distortionless area, of MF AM broadcast stations depends on the radiation properties of the transmitting antenna and the physical constants of the ground surrounding the transmitting site. These ground constants limit the maximum antenna height and establish how large the nocturnal service area will be. In some instances the nocturnal service area can be increased by the use of vertical antenna array. In this case it is very important to know the increase of the theoretical nocturnal service area of the station and if the use of more sophisticated radiating systems is justified. Calculations were made to determine the theoretical nocturnal service area of a station using vertical arrays, and curves with maximum distortionless distance are given as a function of frequency and ground physical constants. Measurements on reduced-scale models in HF and VHF bands are described, and improvements in antenna antifading properties and in nocturnal service area are shown. >
5 citations
References
More filters
01 Sep 1930
TL;DR: In this article, the performance of antenna arrays is analyzed as influenced by certain variables within the control of the designing engineer, such as the number and spacings of the individual couplets.
Abstract: This paper analyzes the performance of antenna arrays as influenced by certain variables within the control of the designing engineer. It starts with an extremely simple analysis of the interfering effects produced by two sources of waves of the same amplitude. This is followed by a short discussion of a paper by Ronald Foster, which considers two antennas and also 16 antennas when arranged in linear array. Two antennas separated in space by ¼ wavelength and in phase by ¼ period give sensibly more radiation in one direction than in the opposite. This, for convenience, has been called a unidirectional couplet. A number of these couplets may be arranged in linear array, thereby giving an extremely useful directive system. Diagrams are shown for such arrays as affected by the number and spacings of the individual couplets. The gains from such arrays are calculated and data are given showing fair agreement between calculation and observation. Directional diagrams for arrays of coaxial antennas indicate that somewhat less gain may be expected from this form than when the elements are spaced laterally. Combinations of these two types of arrays give marked directional properties in both their horizontal and vertical planes of reference. This principle has been used rather generally in short-wave communication. This paper also discusses effects resulting from combining two or more arrays. In one case the space between two arrays tends to emphasize spurious lobes.
21 citations
01 Dec 1924
TL;DR: In this article, the idealized problem of the transmission from a perfect vertical antenna over perfectly conducting plane earth was considered, and conditions for the greatest economy of radiated energy were formulated for the case of a terrestrially located receiving station, the optimum wave length being determined as 0.39 of the fundamental.
Abstract: This paper considers the idealized problem of the transmission from a perfect vertical antenna over perfectly conducting plane earth. The distribution of current amplitude along the antenna is assumed to be sinusoidal. The antenna resistance is entirely radiational and has been calculated in a companion paper. The amount of energy radiated in various altitudinal directions is calculated, and distribution diagrams are given illustrating special cases. The conditions for the greatest economy of radiated energy are formulated for the case of a terrestrially located receiving station, the optimum wave length being determined as 0.39 of the fundamental. A transmitting arrangement of special interest for Heaviside-layer experiments is also described.
18 citations
01 Apr 1935
TL;DR: In this paper, a series of measurements using small models of actual antenna structures resulted in data correlating closely with the performance of the full-sized structures, showing that departures from the simple theory of sinusoidal distribution of current on the tower differ to a major extent from the actual results.
Abstract: The factors influencing the action of towers when used as radiators are considered. It is shown that the results predicted from the simple theory of sinusoidal distribution of current on the tower differ to a major extent from the actual results. A series of measurements using small models of actual antenna structures resulted in data correlating closely with the performance of the full-sized structures. These measurements showed that departures from the simple theory are due to nonsinusoidal current distribution. Several types of recently installed antenna towers are shown to be less effective than the simple theory prediction, particularly with regard to reduction of sky wave and fading. Means for correcting the current distribution and thereby improving the performance are pointed out. The statement that low base capacity is essential to high antenna efficiency is shown to be a fallacy providing simple precautions are taken to reduce conduction losses. The ground system and earth currents are considered from both a theoretical and experimental viewpoint. A simple method of measuring the earth currents is described and it is pointed out that such measurements indicate whether the antenna current is sinusoidal or not. Appendix A gives a method of computing the radiation characteristics and the radiation resistance when the current distribution is known but is not expressed analytically. Appendix B contains the theory behind the ground current measurements. Appendix C shows the influence of the base insulator capacitance on the operating characteristics.
17 citations
01 May 1934
16 citations
01 Dec 1932
TL;DR: In this paper, extensive measurements have been made of the field distribution about a vertical antenna operating at 29 megacycles over sea water with the help of a small, nonrigid airship observations were made at various altitudes which permitted the plotting of the space characteristic and the determination of the attenuation as dependent on altitude.
Abstract: Extensive measurements have been made of the field distribution about a vertical antenna operating at 29 megacycles over sea water. With the help of a small, nonrigid airship observations were made at various altitudes which permitted the plotting of the space characteristic and the determination of the attenuation as dependent on altitude. The experimental results are compared with field intensities computed for the given physical conditions from the theoretical expressions of Sommerfeld and Strutt. Of interest is the manner in which the field is attenuated in the immediate vicinity of the ground plane and the marked effect on the general intensity distribution of the effective height of the antenna above ground. Details are given of the design of the apparatus required for carrying out the measurements.
7 citations