CHIRP signal for Sounder

[zionico90]

Hi guys,

During these days I'm try to simulate a dipole antenna operated as sounder at 9Mhz as central frequency. The bandwidth that must be guarantee is +/- 2.5MHz. (7.5MHz-10.5MHz).
Near the Dipole I have a structure with some boxs and slots. My goal is to measure with a simulation, the E-Field level detected inside the structure.
In order to simulate the problem, I think that the antenna should be operated with a CHIRP as excitation signal. Based on the operating range, how can I modeled the CHRIP signal? Is there a function in Matlab?
If you have some experience to shared with me, I will happy to talk about.

Thank you.

Have a nice day

 

[D.A.(Tony)Stewart]

Metallic slots and gaps will tend to radiate at the 1/4 wavelength (& odd harmonics).. Have you considered the size of the box structure may be bigger than a building at 9MHz?

Or is it a 9MHz radiator and a small slot?

I believe the slot antenna efficiency will be proportional to the ratio of the slot to a 1/4 wavelength at the emission frequencies.

the way to test the design is use a near field probe and spectrum analyzer. The probe can be a short stub or small loop like a shorted scope probe. But generally 9Mhz falls below the 30MHz Electric field bands for EMC and into the magnetic bands for induced conducted line noise.

Any "long chirp" can be used or continuous for quasi-peak measurements as the quasi peak refers the time duration of the burst that falls within the audio bandwidth or >200us typically.

 

[zionico90]

Hi Sunny and thank you for your reply.
Unfortunately the box design is frozen and I can not modify the size of the slots. The problem is to verify the radiated E-Field level inside the structure from the antenna when this is operated in TX and RX (CHIRP signal).

 

[vfone]

https://www.mathworks.com/help/signal/ref/chirp.html

 

[D.A.(Tony)Stewart]

I might be better to measure it on the protoype with an S.A. and near field probe. ( small loop )

Calibrate with a 1% length ( of a 1/4 wave) antenna and generator for field strength at 9MHz.