What is antenna equivalent circuit?
equivalent circuits of antennas in the transmitting and receiving modes are considered to determine the analytical ex- pressions of vectorial transfer functions. The equivalent circuit in the trans- mitting mode is composed of a Thevenin generator which models the source and the TX input impedance antenna, .
How do you calculate the impedance of a dipole antenna?
Before examining the fields radiated by a dipole antenna, consider the input impedance of a dipole as a function of its length, plotted in Figure 2 below. Note that the input impedance is specified as Z=R + jX, where R is the resistance and X is the reactance.
How many ohms is a dipole?
A dipole antenna has, typically, a “twin lead” feed line with an “impedance” of about 300 ohms.
How do you find the equivalent circuit of an antenna?
In order to determine the equivalent circuit you have to obtain the input impedance of the antenna as a function of the frequency. Physically you have a resonant antenna with the resonance frequency f0 equals that of the minimum S11 and a quality factor Q= f0/bandwidth.
How do you draw an equivalent circuit for an antenna?
In HFSS it is not possible to draw equivalent circuit of any antenna… Theoretically, you need to approximate the antenna in terms of R, C and L…… S11= ( ZL-ZO)/ (ZL+ZO), given S11 magnitude and phase and given Zo one can calculate ZL.
What is a resonant dipole antenna?
A dipole antenna commonly consists of two identical conductive elements such as metal wires or rods. Most commonly it consists of two conductors of equal length oriented end-to-end with the feedline connected between them. Dipoles are frequently used as resonant antennas.
What is the impedance of a folded dipole antenna?
The antenna impedance for a half-wavelength folded dipole antenna can be found from the above equation for ZA; the result is ZA=4*Zd. At resonance, the impedance of a half-wave dipole antenna is approximately 70 Ohms, so that the input impedance for a half-wave folded dipole antenna is roughly 280 Ohms.
Does a dipole antenna need a balun?
Because dipoles are balanced and common feed cable, like coax is not. To get maximum signal transfer a balun is required, but typically on say a FM receiving antenna, the signal strength is so strong that it can be omitted in the interest of cost.
Which feeding method is best for dipole antenna?
As the dipole antenna is a balanced antenna, a balanced feeder would be the natural choice to use to feed it. Whilst balanced open wire feeder offers very low levels of loss, and is ideal from many respects it is rarely used.
What is the length of a 40 meter dipole antenna?
Read more about . . . . Dipole Length Calculations.
| Approximate Lengths for HF Ham Band Dipole Antennas | ||
|---|---|---|
| Band (MHz) | Length (Feet) | Length (metres) |
| 7.0 MHz (40 metres) | 68.5 | 21.1 |
| 10.1 (30 metres) | 47.5 | 14.7 |
| 14.00 (20 metres) | 34.3 | 10.6 |
What is the equivalent circuit of a dipole?
• The equivalent circuit of a dipole (or monopole) is a series R-L-C circuit. • At its resonant frequency, it is much easier to couple energy into an antenna and, therefore, it will be a more efficient radiator at its resonant frequency. • Antenna resonance will occur when each arm of the antenna is one-quarter wavelength long.
How do you increase the radiation efficiency of a dipole antenna?
Adding metal (capacitance) to the end(s) of a dipole or monopole antenna willincrease their radiation efficiency A PCB should be mounted as close to a metal chassis as possible, and have itsground connected directly to the chassis. A plastic enclosure should include a metal reference plane.
What is the radiation resistance of a monopole antenna?
The well-known value for the radiation resistance of a thin, half- wavelength dipole is 72 ohms, for a monopole it will be half of that or 36 ohms. It will be difficult for the common-mode voltage (or any other voltage for that matter) to drive much current into the antenna when the input impedance is large.