What is total efficiency of antenna?
What is total efficiency of antenna?
The efficiency of an antenna is a figure-of-merit that describes what percentage available to an antenna radiates. Total efficiency is the ratio of the radiated power to the power incident from the network; it includes both the reflection loss and dissipation of power energy in the antenna.
Can I use a mobile antenna as a base antenna?
3 Answers. Magnetic mobile antenna is supposed to be mounted on the roof of vehicle, thus metallic roof serves as ground plane. If you want to use it as base station antenna, off the vehicle you have to provide similar ground plane.
What are the factors influencing antenna efficiency?
As a practical matter, the maximum directive gain (directivity) of an antenna depends upon its physical size compared to wavelength. The uniformly illuminated aperture type of antenna has been found to give a higher gain in practice than other antennas, at least for large apertures.
What are the losses in antenna?
Return Loss & VSWR Table
| Return Loss in dB | What It Means | VSWR Number |
|---|---|---|
| 0 dB | 100% reflection, no power into the antenna, all reflected back | Infinite |
| 1 dB | 80% reflection, 20% power into the antenna | 17 |
| 2 dB | 63% reflection, 37% power into the antenna | 9 |
| 3 dB | 50% reflection, 50% power into the antenna | 6 |
Does a mobile antenna need a ground plane?
Summary: A Ground Plane is Critical for Proper Performance Some antennas will have the plane built-in, but magnet-mounted ones typically require that one be provided. The magnetically mounted antennas are designed specifically for use in an automobile, which has a metal roof.
What is antantenna efficiency?
Antenna efficiency is an elusive quantity, which is difficult to qualify. We can calculate it easily (close) enough, if we know three things: What the ground lossesare, along with the radiation resistance and coil Q.
How do you calculate the efficiency of an antenna?
Efficiency can be calculated (not exactly, but close enough) if all we know the three Rs (Rr, Rc, and Rg) values. All we have to do is add these factors together to get Rt (Rr+Rc+Rg=Rt), then divide Rr by Rt. For an average 8 foot antenna mounted on an average vehicle, and using an estimated ground losses,…
What is the maximum length of a mobile antenna?
Obviously there is a limit to how long physically an HF mobile antenna can be, with 11 to 14 feet about the maximum (suburban, versus rural). If you live east of the Appalachians, perhaps just 8 feet. Again, the increase in Rr (when electrical length is increased) is due to the current node (point of maximum antenna current) being modified.
How do you increase the radiation resistance of an antenna?
Rr may be as low as .2 ohms (80 meters), to about 36 ohms (full 1/4 wave on 10 meters). As noted above, another way to increase the radiation resistance of an antenna is to use a cap hat. Properly designedand implemented, they increase the effective electrical length, and they raise the currentnode.
