The face on YZ plane is set with the magnetic wall boundary condition MWall. This magnetic wall is also a boundary condition indicating the symmetry. Number of Modes Number of precalculated modes: 5 Number of modes used in the actual analysis: 1 Select modes: none. Go to the [Results] tab.
The corresponding graphs will appear. The reflection characteristics of the full model, half model, and quarter model are shown in the Figure 1. They are all well matched. In the [Chart] , click [Directivity]. Click [Polar Graph], and a polar graph showing directivity like Figure 2 will appear.
The directivity of the full model, half model, and quarter model are shown in the Figure 2. Comparison is done at 4. The most common dipole antenna is a half-wave dipole which is a piece of wire or rod which is one half wavelength in length. The antenna is cut into two quarter wavelength sections.
The transmission line is connected at center point as shown. The dipole antenna has an impedance of about 73 Ohm. Now if I have an HF radio that can work with different types of antennas, you should connect the coaxial cable connector of the antenna a whip monopole antenna for example into the radio antenna connector, right? If you get another antenna that is a dipole, should its coaxial cable connector connect to the radio antenna connector also?
That wouldn't make sense because one lead will connect to ground and that shouldn't be the case with dipole antennas as they are half-wave antenna, right? If right, so how do you connect them? Can you please clarify this for me?
RadioRon Well-Known Member. Yes, it is like they say in that website. For a monopole, the connection at the antenna is that the center conductor is connected to the base of the radiating element, and the outer shield of the cable is connected to the ground plane. For a dipole, the center conductor is connected to the base of one of the two radiating elements, while the outer shield of the cable is connected to the base of the other element.
It might be confusing if you think that the shield of your coaxial cable is a ground connection. Many beginners think of "ground" as a place where there is no voltage and no resistance, a place where all the current goes to disappear. At radio frequencies and especially on transmission lines like coax, there is just as much current flowing on the ground wire the shield if we talk about coax as there is in the center wire.
The shield isn't really a "ground" at all, its just the second conductor in a two conductor cable. In the same sense, the outer shell of your radio transceiver is not an ideal ground either. It may be connected to the ground wire in the wall through its power cord, but that doesn't mean that the high frequency voltages and currents are zero at the radio chassis. There is a kind of magic in coax cable. Its not really magic, but until you understand the physics of it all, it does seem that way.
You see, the electrical energy is flowing inside the coax, but not on the outside in the ideal case. Where the coax connects to your radio, the outside of the radio case has no high frequency voltages or currents on it at all, so you can touch it and nothing will happen.
But inside the metal case the high frequency currents and voltages exist on the inner wall of the metal housing. When you connect a coax cable to this box, the energy inside the metal housing can flow to the antenna by conducting on the outside of the coax cable center conductor, and on the inside of the coax cable shield.
In the ideal case, it stays inside the cable and does not leak out. This remarkable behavior is the result of the skin effect, which is something you can look up and study. The skin effect is what we call the behavior of high frequency energy to stay on the surface and not penetrate through solid metal. Anyways, the same thing happens with signals picked up on the antenna. They conduct into the inside surfaces of the coax cable and down to the radio chassis, staying always on the inside in the ideal case.
Dipole electromagnetic field pattern Monopole antenna electromagnetic field pattern Both monopole and dipole antennas exhibit similar radiation patterns and performance, except that monopole antennas are not symmetric vertically. Pasternack Enterprises Inc United States. Upvote 1 Downvote Flag it Comments 0. Upvote 1 Downvote Flag it Comments 1. Fritz Caspers Nov 27, Tags Wireless Charging. More Calculators. What is Foreign Object Detection?
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