ELMER - it is free simulation tool, not only for magnetic field. I havent tried it yet, it is too complicated for me. NEC2 is freely avalible. It is a very good learning experience to write and play with.
If you are not up to that there is this. This is becoming a rather handy reference. I wonder if Dave should make it a sticky? Kelbit Regular Contributor Posts: 58 Country:. I previously posted in another thread about this Pages: [ 1 ] Go Up. Another challenge involves the effect of the enclosure on antenna sensitivity. Many times, the plastic used for an enclosure will have a higher dielectric constant than air.
The lack of sufficient clearance between the antenna and the enclosure causes the antenna to see a higher effective dielectric constant. As a result, the electrical length of the antenna increases and the resonant frequency decreases. Design teams should always verify the performance of the antenna matching network with the final plastic enclosure in place and the product installed in a typical use scenario.
At high frequencies, the impedance of an RF circuit changes when measured at different distances from the load. The width and thickness of the RF trace, the clearance between the trace and ground along with the substrate type also affect the amount of impedance change.
In a PCB antenna, coaxial cables, microstrip lines, and coplanar waveguides function as transmission lines. Common practices involve using a passive circuit as a matching network to transform the characteristic impedance of the RF trace and to ensure the maximum power transfer between matching source and load impedances.
The use of high-speed circuits within electronic products that utilize PCB antennas increases the risk for electromagnetic interference and radiated emissions. Simultaneous Switching Noise SSN caused by the downscaling of integrated circuits and the increased clock frequencies of microprocessors results in self-jamming—or the introduction of signals that negatively affect the signal-to-noise ratio and distort the signal transmitted by an antenna.
In the same way, the antenna can cause self-jamming along its transmission lines and degrade signals throughout the PCB. PCB antenna design software accurately analyzes the filters, microstrip lines, and passive components that make up a PCB antenna.
The software also assists with PCB antenna design by displaying metal-dielectric layers, feeds, and connector types. To meet modern design requirements, PCB antenna software provides the antenna geometrical and electrical properties for optimal performance. Establishing these properties allows the software to model the correct antenna impedance and radiation pattern.
Altium Designer provides the Schematic Editor, the PCB Editor, and signal integrity analysis tools for controlling and matching impedances needed for consistent PCB antenna performance. The Schematic Editor and PCB Editor ensure that impedance matching occurs from the output pin to the target input pin.
In addition, the Editors suggest the addition of termination components to achieve matching throughout the circuit and decoupling capacitors or materials used to prevent the mutual coupling between antennas. Design teams can find the correct components for supporting the PCB antenna design through database libraries or the Altium Vault.
Signal Integrity Analysis tools in Altium Designer identifies any nets that could have unacceptable levels of reflection. The tools also predict potential levels of signal reflection and crosstalk while providing a what-if analysis of potential termination components. The combination of the Editors, Design Rules, and Active Route ensures that the correct routing path for the signal occurs and that an unbroken path for the return current exists under the signal route.
With these techniques, Altium Designer prevents EMI and provides the best design for optimal antenna performance. While placing shields on clocks, microcontrollers, and switching power supplies provides one solution for eliminating EMI, any shielding will block transmitted signals and should not cover the antenna. Altium Designer can protect against self-jamming with a combination of design rules for routing and its Active Route function.
The output traces from the clock should run over the ground plane to reduce any current induced by stray RF fields and minimize loop areas. Altium Designer also assists with eliminating net antennas that can cause self-jamming through the optimal placement of ground planes. Any ground plane placed directly below the clock allows forms a net antenna.
When designing a PCB antenna, teams can use the Layer Stack Manager to specify each layer for the type of material, the thickness, and the dielectric constant. The option applies an industry-standard equation to translate the impedance into a width setting. Design teams can import the component model into the library editor and the enclosure into the PCB Editor to perform accurate collision testing. With these tools, design teams make the needed adjustments for circuits and enclosures to ensure that the plastic does not affect the dielectric constant.
While many PCB antenna software applications provide needed tools, Altium Designer places schematic and Circuit Board tools in one environment.
Powerful design tools such as the Layer Stack Manager and Signal Integrity Analysis tools respond to the same menus, commands, and function keys. The efficiency of this antenna depends upon the size of the loop and the copper material used in its design. When compared with the wavelength, the loop antennas are too much inefficient, so they are not used for transmission but can be used as receptors.
As the loop antenna has a directional pattern, it is used to find out the transmitter also called radio direction finding RDF. To resonate at the operating frequency, one must attach a capacitor in parallel with the antenna. As discussed earlier, an impedance matching network is essential to achieve maximum efficiency.
The patch antenna looks like a rectangular or circular patch of copper on PCB. The span of the patch antenna is about one-half of the wavelength of radio waves. The practicality of patch antenna is at microwave frequencies because short wavelengths help to design small-size patches. Thanks to its ease of design on printed circuit boards, portable devices using wireless functionality mostly use patch antennas.
Planar inverted type of antenna is a variant of the patch antenna. Its strong radiations can be observed perpendicular to the patch. WLAN antennas and phased arrays both use this type of antenna to have maximum gain with narrow beamwidth. There is a bandwidth problem in this type, but by using a thicker dielectric between patch and ground plane, the bandwidth of the Patch antenna can be increased. This is an omnidirectional antenna having a large ground plane for maximum efficiency.
Some part of F patch does not use copper but is a plane surface in this type of PCB antenna, which helps to expand the bandwidth of the antenna. Monopole antenna is used in this type, which runs parallel to the ground plane and the other end is grounded.
This antenna has two advantages on the monopole. One is its shorter size or compactness. The other is that its impedance matching is controlled by designers, so we do not need external matching components for impedance matching.
This antenna construction is done by folding the conductors back and forth so that antenna can be made shorter. This design results in a smaller compact size, but with the loss of radiation resistance, efficiency, and decrease in bandwidth. Multiple experiments are performed to select the best combination for a specific application.
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