PCB antenna designs

I think it is very easy to implement by write a ULP and not need libray..

EAGLE CAD also have another ulp for antenna draw. if you know C, you can write it yourself. or you can ask one.

I will write this ulp as my first excersise. but I no instrument to test and verify..

Hi,

Good idea and thanks for the effort, I have pretty much no programmin experience so I can't do this myself  with an ULP.

I do not have a spectrum analyser available but in some time I should be able to make some tests with a ev-kit and then see some RSSI values.

I am currently moving though so it will take some time for my CNC to be operational so I can't tell when can I could get them machined.

With an ULP I guess you can directly implement the calculations for the antenna length regarding the groundplane size etc. and have settings for the substrate thickness.

Would be great!

Elias

I have noticed  that two endpoint of a wire all is round.  if it is can not be ignored, I think it can be use a Rect shape add to the two endpoint  to resolve this problem.

I want write a ulp to use it generate a library.

could you provide a correct formula to calculate these parameter ?

I have no experience on this.

Hi huayuliang,

I'm sorry I didn't understand what do you exactly mean. Do mean the shape of the wire ending in EAGLE itself or what?

Please let me know and I will do my best to assist you.

Elias

Hi huayuliang,

I'm sorry I didn't understand what do you exactly mean. Do mean the shape of the wire ending in EAGLE itself or what?

Please let me know and I will do my best to assist you.

Elias

sorry for my bad english, to explain my means, I uploaded one image.

No problem, thanks for the picture.

As far as I know it is not possible to change the end style of a wire in EAGLE.

Rectangles are drawn differently on the grid in comparison to wires, they are "between the lines" when wires are "on the lines".

Also the round cap is added to the absolute width of the wire.

Maybe it would be best to use the rectangle as the whole wire and just adjust the grid size to the width you want the "wire" to be.

In the attachment you can see rectangles at 0.1mm, 0.25mm and 0.55mm widths and also an 0.4064mm wire, all with same coordinates as end and starting points (11.2 to 15.0).

All of the rectangles are exactly 3.8mm long but the wire is 4.2mm.

Hopefully this helps in some way.

Attachments:

yes, I think it is best way to resolve this problem by place rectangles at the end of wire with same width.

btw, which type of antenna you need first ? is there have a formula for it ? and whether is it need to do electromagnetic simulation ?

I think if only use the value thar user input, will be the simplest.

Hi,

I think it could be difficult to use rectangles to cap the wire due to the different placement of them on the grid as I showed.

So it might be easier to use only rectangles instead of wires but I'm not sure.

Mainly I'm looking for a 868MHz antenna at the moment like the inverted F-antenna here: http://focus.tij.co.jp/jp/lit/an/swra228b/swra228b.pdf

You might want to take a look at http://www.freescale.com/files/rf_if/doc/app_note/AN2731.pdf , http://www.numatechnologies.com/pdf/an_antenna.pdf and http://www.numatechnologies.com/pdf/foilantennas.pdf for example to find out more about the antenna measurements etc.

The board thickness and material have a big effect on the antenna tuning so I think there has to be settings or different scripts for different substrates.

I use 1.6mm FR4 myself.

Hello,

The antenna discussions here are pretty interesting. Since the wires have rounded edges, probably a wire cannot be used for the antenna design. It is possible to draw rectangles (instead of wires) with the required dimensions as long as it is in the "91 nets" Layer. I guess, the main important criteria in the antenna design is the measurements, dielectric material used and the distance between the ground layer. Yes, there has to be different scripts for different substrates for which the distance with the ground plane might vary depending on the impedance matching.

-Jaya

Hi.

Round edge  only present on both two end point of wire, so I think there is only need place draw rectangles on the both end point.

of cause, all of them can be drawn in rectangles,

If I use wire and little rectangles I need subtract half one width of wire. but other drawing will be very easy.

but sorry, I don't understand the "91 nets" Layer in here. as my self I think there only need one pad, I want make it become a device.

Hi,

If you want to "cap" the ends of the wire with  rectangles that might be tricky to get them placed exactly correctly.

Normally  if you look at the grid and draw a wire, it will be drawn on top of a  grid line, where if you draw a rectangle it will be between the grid  lines.

That is why I thought it could be easier to use rectangles only.

See the attached image to better visualize what I mean.

Elias

Attachments:

Huayuliang,

I meant by saying that , since the wires are always drawn in the Layer "91 nets" , so if we need to replace wires by rectangles then we need to make sure that the rectangles are drawn in the Layer "91 nets".

R-

Jaya

sorry sir , I can't understand your mean.

the layer 91 only can be use in schematic editor , how can I draw a rectangles on layer 91 in library editor?

for an antenna, it generally be place on top or bottom layer. even you mirror it, the element of package can be automatic mirror.

Indeed nets layer is used only in schematic.

For boards you need to use top or bottom layer as with wires also if you want them to be actually made.

Elias