ITPI20090131A1 - COMPACT MULTIRISONANT ANTENNA WITH DOUBLE SPIRAL WITH PARASITE ELEMENT - Google Patents

Description

DESCRIPTION OF THE INVENTION

The object of the present invention is an antenna with multiple resonance within radio frequency and / or microwave bands, such as for example the UHF one.

Another object of the invention is to provide an antenna which can be easily integrated with the electronic circuitry.

A further object of the invention is to provide an antenna of reduced dimensions, of high implementation simplicity, which can be directly produced on PCB (Printed Circuits Boards).

These and other purposes are satisfied by a multi-turn antenna with a parasitic element composed, in the reference application case of two turns reported here, by the following components:

- A first turn connected to the electronic circuitry; - A second coil inside the first coil;

- A parasitic element;

- A matching network connected to the loop connected to the generator or to the electronic circuitry.

In particular, said antenna operates on radio frequency or microwave sub-bands, as a non-limiting example frequencies belonging to the UHF band.

Advantageously, the perimeter of the two turns and the length of the parasitic element determine the position and width of the two working bands within the UHF band.

Advantageously, the perimeter of the outer loop is fixed; the inner loop and the parasitic element can be sized to fix the other resonance frequencies.

Advantageously, the matching network determines the adaptation of the antenna to the signal generator or to the electronic circuitry.

Advantageously, the matching network is integrated directly on the same plane as the antenna and requires low-cost components.

The antenna object of the present invention can be printed on dielectric material, with assigned dielectric permittivity constant. In this way, a low-cost antenna suitable for series production is obtained.

Advantageously, the antenna is made on only one side of the dielectric substrate.

The antenna is planar, low profile and small in size and therefore can be advantageously used in all sensor networks or for point-to-point communications.

Drawings

The invention will be illustrated below with the description of some of its embodiments, presented by way of non-limiting example, with reference to the annexed drawings in which:

Figure 1 shows in plan a first example of a; according to the invention;

figure 2 shows a three-dimensional view of the first example of antenna according to the invention;

Figure 3 shows a plan view of a second example of an antenna according to the invention;

figure 4 shows a three-dimensional view of the second example of antenna according to the invention;

figure 5 shows the value of the input impedance (real part and imaginary part) of the antenna shown in figure 1, according to the invention;

figure 6 shows the value of the input impedance (real part and imaginary part) of the antenna shown in figure 3, according to the invention.

Description of the preferred embodiments.

In the following description two preferred embodiments of antenna according to the invention will be discussed.

Figure 1 shows a plan view of an antenna according to the invention, printed on a dielectric (1), with a thickness of 1.6 mm and a dielectric constant of 4.35, by means of a photolithographic technique. The width of the tracks traced in the proposed solution is equal to 1.25 mm. The first loop (2) has a total perimeter of about 16 cm and the impedances (5) and (6) of the matching network are connected to it, both having a value equal to 33nH. The second coil (3) has a perimeter

of about 21.6 cm while the parasitic element (4) length equal to about 4 cm. The antenna is electrically connected to the generator or to the electronic circuitry through the tracks (7) and (8).

Figure 2 shows a three-dimensional view of the first antenna shown as an example.

Figure 3 shows a plan view of a further embodiment according to the invention. The first loop (2) has a total perimeter of about 16 cm and the impedances (5) and (6) of the matching network are connected to it, both having a value equal to 33nH. The second coil (3) has a total perimeter of about 39 cm while the parasitic element (4) has a length of about 4.6 cm. The antenna is electrically connected to the generator or to the electronic circuitry through the tracks (7) and (8).

Figure 4 shows a three-dimensional view of the second antenna shown as an example.

Figure 5 shows the value of the input impedance offered by the first antenna and the resonance frequencies 1 and 2 are highlighted, with values equal to 415 MHz and 915 MHz respectively.

Figure 6 shows the value of the input impedance offered by the second antenna and the resonance frequencies 1,2 and 3 are highlighted, with values equal to 315 MHz, 705 MHz and 915 MHz respectively.

The above description of two specific executed forms is able to show the invention from

conceptual view so that others, using known techniques, will be able to modify and / or adapt this specific embodiment in various applications without further research and without departing from the inventive concept, and, therefore, it is understood that such adaptations and modifications will be considered as equivalent to the exemplified form of execution. The means and materials for carrying out the various functions described may be of various nature without thereby departing from the scope of the invention. It is understood that the expressions or terminology used have a purely descriptive purpose and therefore not limitative.

Claims (8)

CLAIMS 1. A multi-loop antenna with multiple resonance bands. 2. A low pr antenna, according to claim 1, characterized in that it comprises: - A first turn connected to the electronic circuitry; - A second coil inside the first coil; - A parasitic element; - A matching network connected to the loop connected to the generator or to the electronic circuitry. 3. An antenna, according to claim 1, which operates in the radiofrequency or microwave bands of the electromagnetic spectrum, and in particular at UHF frequencies identified by the IEEE standards of the Institute of Electrical and Electronic Engineers (IEEE). An antenna according to claim 1 which operates simultaneously in distinct sub-bands within the band of claim 3. 5. An antenna, according to claim 1, which is capable of operating in transmission and / or reception. 6. An antenna, according to claim 1, printed on only one side of the supporting dielectric substrate. 7. An antenna according to claim 1, wherein the matching network is integrated directly on the same plane as the antenna with low-cost components. 8. An antenna which, according to claims 1, 2, 3, 4, 5,6 and 7 and maintaining the same operating principle, can simply be modified with suitable scaling factors of the adaptation network, shapes of the radiating elements similar to those of the antenna presented and suitable materials, to operate in lower or higher frequency bands of the electromagnetic spectrum than the one presented.