Why quarter wavelength antenna

In addition to that, simply, when you have a TL. If you measure an impedance on somewhere in TL, you are certain that, you will measure the same impadance after going half wavelength on the TL. It is a basic knowledge in antenna field. Please have a look some books about theory of antenna. If you take a look at some the theory and equations for basic transmission lines you will notice that at a quarter, one eighth and half a wavelenght points, interesting transformations happen.

You can transfer you load as it were connected directly to your generator. Similar threads B. RF, Microwave, Antennas and Optics. Started by kwagjj Oct 29, Replies: 4. The quarter-wavelength in filter Started by laperla Dec 14, Replies: 2. Microstrip line wider than quarter wavelength. Started by shmily Dec 3, Replies: 8. Part and Inventory Search. Welcome to EDABoard.

Angling the radials in a downward fashion has been outlined above. Another is to use a folded element. In the same way that a folded dipole increases the feed impedance of the antenna, so a folded vertical element can be used. If the diameter of both sections is the same, then an increase by a ratio of is achieved. By using a smaller diameter grounded element the feed impedance can be reduced so that a good match to 50 ohm coax can be achieved.

The quarter wave vertical antenna is widely used in view of its simplicity and convenience. To improve on its performance other types of vertical are available. It is also possible to use further verticals and feed them with different phases to provide gain to the overall antenna system. Basic quarter wavelength vertical antenna As the name suggests the quarter wave vertical antenna consists of a quarter wavelength vertical element.

Basic quarter wave vertical antenna showing current magnitudes The ground is obviously an important part of the RF antenna. Please help to provide an answer to help intuitively. Add a comment. Active Oldest Votes. Improve this answer. Sessink F. Sessink 1, 1 1 silver badge 9 9 bronze badges. Just a small follow up question - All antennas will work only in Half Duplex mode, right?

All antennas working in Bluetooth, WiFi frequency bands etc.. And the association RF transceivers will also working in Half-Duplex mode right? So, at any one time, it can either transmit or receive. Full-duplex is low-power, low range OR time-division multiplex, or frequency-division multiplex. Tx and Rx at the same time. Show 1 more comment. If we make the antenna 5-meters tall, the impedance seen by the generator will follow the green curve in the graph below as we change the frequency of the generator: Notice that the antenna has the least resistance to the flow of current - the lowest impedance - at about This will help all participants to keep track of questions, discussion and answers.

Show 2 more comments. Richard Fry Richard Fry 2, 5 5 silver badges 17 17 bronze badges. Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password.

Post as a guest Name. Email Required, but never shown. Featured on Meta. Now live: A fully responsive profile. Answer: No. It does not require a ground plane to work efficiently. If the length of the dipole, i. If a full wavelength dipole is used either for transmission or for reception, let us see how the radiation will be.

This is accomplished by using a DC grounded base coil construction. Copper is a best suited material for base antennas. The metal, while soft and malleable, is quite rigid. Stainless steel has a higher tensile strength, so thinner wire can be used. This antenna wavelength calculator can be used to determine the physical length of an antenna's electromagnetic wave in free space. Full wave, half wave, and quarter wave antenna structures can be selected.

In fact, most simple antennas have a length close to half the wavelength of the signal they are built to receive. Why quarter wavelength is used?