In this paper, microstrip-fed slot antennas with suppressed harmonics are proposed. To obtain this operation, conductor lines connected with ground plane are inserted in slot antennas. To verify the validation of the proposed antennas, the equivalent circuit analysis is presented. Also, the miniaturization and bandwidth enhancement of the antenna for various applications are achieved. (a) A rectangular patch microstrip antenna fed with a microstrip edge feed. (b) A circular patch microstrip antenna fed with a coaxial probe feed. The patch shapes in Figure 5.1 are symmetric and their radiation is easy to model. However, application specific patch shapes are often used to optimize certain aspects of MSA performance.
The above diagram shows a patch antenna from the Transmission Line Model perspective. We can observe the fringing at the edges increasing the effective length.
For an efficient radiator, a practical width that leads to good radiation efficiencies is,
Conductance: Each radiating slot is represented by a parallel equivalent admittance Y(with conductance G and susceptance B). The slots are labeled as Θ1 and Θ2. The equivalent admittance of a slot is given by,
Y1 = G1 + B1
Where for a slot of finite width (W)
Since both the slots are identical, its equivalent admittance is;
Y2= Y1, G2=G1, B2=B1
The conductance of each slot can be obtained by using field expression from cavity model. In general, the conductance is defined as
The above list of equations obtained from the transmission line model can be used to calculate parameters for analysis and synthesis of antenna. For these purposes, number of models may be used in conjunction with each other.
Double-slot-fed microstrip antennas for circular polarization operation
Abstract
Using the cavity model theory, simple design formulas are developed for double-slot-fed circularly polarized microstrip antennas. Equivalent magnetic current sources are assumed at the slot positions and then the electric field distribution under the patch is obtained in terms of cavity modes. By applying the circular polarization conditions to the far-field components of the electric field, the loci of the positions of the slots for the circular polarization operations are found. Experimental results are successfully demonstrated based on the theoretical designs.
The following effects are taken into account for this model:
Fringing Effects: As the dimensions of the patch are finite along the length and the width, the fields at the edges of the patch undergo fringing i.e. the field exists outside the dielectric thus causing a change in the effective dielectric constant. It is a function of the dimensions of the patch and the height of the substrate.
The above diagram shows a patch antenna from the Transmission Line Model perspective. We can observe the fringing at the edges increasing the effective length.
For an efficient radiator, a practical width that leads to good radiation efficiencies is,
Conductance: Each radiating slot is represented by a parallel equivalent admittance Y(with conductance G and susceptance B). The slots are labeled as Θ1 and Θ2. The equivalent admittance of a slot is given by,
Y1 = G1 + B1
Where for a slot of finite width (W)
Since both the slots are identical, its equivalent admittance is;
Y2= Y1, G2=G1, B2=B1
The conductance of each slot can be obtained by using field expression from cavity model. In general, the conductance is defined as
The above list of equations obtained from the transmission line model can be used to calculate parameters for analysis and synthesis of antenna. For these purposes, number of models may be used in conjunction with each other.
Double-slot-fed microstrip antennas for circular polarization operation
Abstract
Using the cavity model theory, simple design formulas are developed for double-slot-fed circularly polarized microstrip antennas. Equivalent magnetic current sources are assumed at the slot positions and then the electric field distribution under the patch is obtained in terms of cavity modes. By applying the circular polarization conditions to the far-field components of the electric field, the loci of the positions of the slots for the circular polarization operations are found. Experimental results are successfully demonstrated based on the theoretical designs.
Approximate Model For Microstrip Fed Slot Antennas Antenna
- Antenna Design;
- Circular Polarization;
- Integrated Circuits;
- Microstrip Antennas;
- Slot Antennas;
- Antenna Radiation Patterns;
- Cavity Resonators;
- Electric Fields;
- Far Fields;
- Communications and Radar
