by British Broadcasting Corporation .
Written in English
|Statement||by P.Knight, and R.E.Davies.|
|The Physical Object|
|Number of Pages||44|
BBC Monograph Tables of Horizontal Radiation Patterns of Dipoles Mounted on Cylinders. P. Knight, R.E. Davies. tables of horizontal radiation patterns of dipoles mounted on cylinders report no. e (/13) the british broadcasting corporation engineering division. title: bbc rd author: tables of horizontal radiation patterns of dipoles mounted on cylinders subject: p knight, re davies. An understanding of the dipole radiation pattern enables the antenna to be orientated in the optimum direction at any time. Radiation pattern & polar diagram As the directional performance of an antenna is the same in transmit and receive, it does not matter which mode is measured to produce a plot of the radiation pattern. Much confusion exists about the radiation patterns of antennas. In particular, the horizontal dipole is misunderstood by most who use it. It is generally assumed that a horizontal dipole has a radiation pattern which aims most of its signal toward the .
Click here to see a table of the elevation effects on antenna radiation pattern for these bands: m, 75/80m, 40m, 20m, 15m, 10m and 6m Below, are graphs and an animation of what happens to a resonant horizontal dipole according to feed point height over average ground. Dipole Antenna Radiation Patterns Much confusion exists about the radiation patterns of antennas. In particular, the horizontal dipole is misunderstood by most who use it. It is generally assumed that a horizontal dipole has a radiation pattern which aims most of its signal toward the horizon, perpendicular to the line of the antenna. emitted from the ends of the doublet; and (2) maximum radiation comes from the doublet in a direction perpendicular to the antenna axis. This type of radiation pattern is both NONDIRECTIONAL (in a horizontal plane) and DIRECTIONAL (in a vertical plane). From a practical viewpoint, the doublet antenna can be mounted either vertically or horizontally. ments of vertical dipoles since the radiation patterns of all the elementary doublets which form a dipole are identical in shape. The h.r.p.s of horizontal dipoles mounted on a cylinder could be calculated by applying the formulae for tangential and radial doublets to the elementary doublets forming the dipoles but the necessary.
A program to find the currents at the bases of the dipoles of a log-periodic dipole antenna is written in MATLAB. In the program ―admittance matrix approach to LPDA‖ explained above is used. Tau, sigma, characteristic impedance of the feeder element, length of the dipoles and the spacing between the dipoles are the inputs for the program. On 20 meters, you should expect dB gain over a dipole and a 6-lobe radiation pattern with an elongated figure 8 pattern perpendicular to the plane of the antenna. This is typical of a 3 element collinear array. For a simple explanation of collinear arrays read “Troubleshooting Antennas and Feed lines” by Ralph Tyrrell, W1TF. The dipole is usually mounted horizontally, but if mounted vertically, its transmission line feeder cable should extend from it at a right angle for a distance of at least a quarter wavelength. In free space, the radiation pattern of a horizontal half-wave dipole is similar to that of the small dipole shown in Fig. and has a directivity of. The antenna, including the Ω feedline, should also be mounted as far from other structures as possible. This includes the ends of the wire elements, which are actually the most sensitive part of the antenna. Any objects, metal in particular, within the near-field radiation pattern can affect the impedance and radiation pattern of the antenna.