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Some time ago I got the Linx..... :)

In the mean time I changed my plan and decided to add the linx to a ready made product.

Plantraco makes a nice 4 ch RX witch happens to handle 10 gram servo's very well.

Also they have a so called monolith TX witch plugs in the trainer port of a Futaba Tx.

The monolith has an IA4221 chip with a kind of open loop antenna.

The datasheed however gives an output network (page 28 as I remember) for a singel ended dipole antenna

So first I did changed the antenna to see if it works.

And it does.

It is rather strange but range appeared to be twice as far! (now it is about 500 mtr) after the modification.

Now I have some questions...

Again an output network: also "tons of harmonics and noise"? ...This output network seems to be less complicated and promised to have some self tuning abilety at least for those loop antenna's. Only special RF components were used in the modification. Anyone (Thomas?) can give me a prediction?

Can I just connect the Linx to this antenna system without adding components in between?

What can I change to the PCB design, where should the microstrip start?


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  • 2 weeks later...

With the Linx mounted on a new pcb I did a range test.

Again an 8,2 cm wire antenna was attached with no ground plane to mention.

Now range is at least 1500 meter!!!!!(close to the ground) At that distance my video connection was too bad.

Strong stuff...

I like to make a patch antenna and see what distance can be reached.

Thomas, you use a brass front side for your improved patch. Do I need to repeat also that material?

My plan is to solder the patch directly to the pcb, no sma connectors. For 868mhz the distance between the plates will be about 10mm. Would it be wise to use a piece of 50 ohm coax to connect the upper plate?

(and still those harmonics! I am afraid to ask!)



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