Printed PIFA antenna and method of making the same

1. A printed PIFA antenna comprising:

a first and second substrates stacked in thickness direction;

a radiating element comprising a first and second radiating traces respectively disposed on upper surfaces of said first and second substrates;

a connecting trace for connecting said first and second radiating traces;

a part of a ground portion disposed on the upper surface of the first substrate;

a shorting trace for shorting said radiating element to the ground portion; and

a feeder cable comprising an inner conductor electrically connecting with the radiating element and an outer shield conductor electrically connecting with the ground portion.

2. The printed PIFA antenna as claimed in claim 1 , wherein the radiating element is a substantially U-shaped printed trace.

3. The printed PIFA antenna as claimed in claim 1 , wherein the ground portion extends along the upper surface of the first substrate, side surfaces of the first and second substrates and a lower surface of the second substrates.

4. The printed PIFA antenna as claimed in claim 1 , further comprising a first and second holes, in which the connecting trace and the shorting trace are respectively disposed.

5. A printed PIFA antenna for an electronic device, comprising:

a multi-layer dielectric substrate;

a radiating element being disposed on at least two layers of the substrate;

a ground portion disposed on at least one surface of the substrate;

a shorting trace disposed through one layer of the substrate for shorting the radiating element to the ground portion; and

a feeder cable comprising an inner conductor electrically connecting with the radiating element and an outer conductor electrically connecting with the ground portion.

6. The printed PIFA antenna as claimed in claim 5 , wherein the radiating element is rectangular-wave shaped printed trace.

7. The printed PIFA antenna as claimed in claim 5 , further comprising at least one hole through at least one layer.

8. The method of making a printed PIFA antenna for an electronic device comprising the steps of:

a. choosing a multi-layer dielectric substrate;

b. determining the length of a radiating element according to predetermined operating frequency and dielectric constant, curving the radiating element to a predetermined shape according to the determined length of theradiating element and then disposing the radiating element on each layer of the substrate;

c. disposing a ground portion on a surface of the substrate and disposing the radiating element on the layers of the substrate;

d. providing a shorting trace for shorting the radiating element to the ground portion;

f. providing a feeder line which comprises an inner conductor and an outer conductor and respectively electrically connecting the inner conductor with radiating element and the outer conductor with the ground portion.

9. The method of making a printed PIFA antenna as claimed in claim 8 , wherein the radiating element is rectangular-wave shaped printed trace.

10. The method of making a printed PIFA antenna as claimed in claim 9 , wherein the ground portion extends along a lower surface, a side surface and an upper surface of the substrate.

11. The method of making a printed PIFA antenna as claimed in claim 10 , wherein the feeder cable is a coaxial cable comprising the inner conductor electrically connecting with a part of radiating element disposed on the upper surface of the substrate and an outer conductor electrically connecting with a part of the ground portion disposed on the upper surface of the substrate.

12. A printed PIFA antenna comprising:

a multi-layer dielectric substrate defining upper, middle and lower levels vertically;

a radiation trace and a ground trace located at the upper level;

another radiation trace located at the middle level;

another ground trace located at the lower level;

a side ground trace disposed between the upper and lower levels and connecting the ground trace to the another ground trace;

a connection trace disposed between the upper and the middle level and connecting the radiation trace to said another radiation trace;

a short trace disposed between the middle level and the lower level and connecting said another radiation trace to said another ground trace; and

a feeder cable having inner conductor connected to the radiation trace and an outer conductor connected to the ground trace.

13. The antenna as claimed in claim 12 , wherein the connection trace and the short trace are located at two opposite end areas of the substrate in a lengthwise direction thereof.

14. The antenna as claimed in claim 12 , where said another ground trace extends longer than all other traces in a lengthwise direction of the substrate.