DN038 helical antenna for 1.24mm PCB

Ef Misoyannis

Other Parts Discussed in Thread: CC1190, CC110L

Hi There,

I need to design a PCB helical operating at 915MHz using 1.24mm 4 layer board as I'm going to add it to the CC112X/CC1190 reference design. DN038 specifies a helical antenna but it's optimised at 868MHz however it works at 915MHz with reduced efficiency. DN038 also states it's designed for 0.8mm board but will work with reduced efficiency on 1.24mm board.

I'm worried if I use it "as is", the cumulative efficiency reductions of 915 v 868 and 1.24 v 0.8 will give me a less than ideal result. Is there any documentation outlining how to re-design the antenna and how to re calculate the matching components for 915MHz and 1.24mm board?

over 12 years ago

0 RGW over 12 years ago

TI__Mastermind 33160 points

Hi,

The antenna structure can be copied directly but the matching network components will have to be changed. The new match values will depend on your board size and surroundings.

Best regards,

Richard

0 Ef Misoyannis over 12 years ago in reply to RGW

Prodigy 50 points

Hi Richard, I need to know what the impedance of the antenna will be at the new frequency and new board thickness so I can calculate the new match components. Is there a document that provides the formulas or tables with this information?

0 RGW over 12 years ago in reply to Ef Misoyannis

TI__Mastermind 33160 points

Hi,

We have no document with this information. Do you have access to a VNA ?

The matching values will be dependent on the GND plane size and the surroundings so I would just assemble a zero ohm resistor and measure the impedance with a VNA to calculate the match values.

Regards,

Richard

0 Ef Misoyannis over 12 years ago in reply to RGW

Prodigy 50 points

Hi Richard,

I don't have easy access to a network analyser but I'm sure I can find one.

Thanks

0 Ankit over 12 years ago in reply to Ef Misoyannis

Prodigy 80 points

Hi,

I am using DN038 antenna but I have to make slight modification. I am introducing a hole at the bottom right corner just above the ground plane. Will that change the antenna characteristics??

Regards

Ankit

0 RGW over 12 years ago in reply to Ankit

TI__Mastermind 33160 points

This can be compensated for when choosing the antenna match components so this will not be an issue.

Regards,

Richard.

0 Aleksander Bologna over 10 years ago in reply to RGW

Prodigy 15 points

Hello Richard, I am an amateur user of the CC110L Evaluation Module. I was wondering if you had the antenna matching components for 915MHz operations?

0 RGW over 10 years ago in reply to Aleksander Bologna

TI__Mastermind 33160 points

Hi,

If you change the 12 nH to 10 nH then this should work fine for 915 MHz.

Regards, Richard

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DN038 helical antenna for 1.24mm PCB