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How to apply frequency-dependent Antenna Factor

 

Good day,
?
I would like to know whether I can apply the Antenna Factor (AF) for my calibrated biconical antenna to measurements being made by the TinySA Ultra. Antenna theory refresher: The AF is a value that lets you go from measured intensity to actual E-field intensity. It is critical when doing compliance testing of radiated emissions.
?
If the AF was just a single value I could apply it to the TinySA settings as a pretend attenuator between the antenna and the TinySA. But the AF of my antenna is highly frequency-dependent, varying by over 20dB over my frequency range of interest.?
 

Using TRACE/CALC/TABLE TRACE you can create a trace containing a 8 point linear interpolation of the AF versus frequency.
Suggest to use TRACE 4 for the table.
Now you can use the TABLE TRACE as correction by selecting TRACE 1 and using TRACE/SUBTRACT/TRACE 4
--
Designer of the tinySA
For more info go to

 

Hi Erik,
?
Thank you for the suggestion. Is the trace limited to 8 points linearly interpolated? This may work fine in a pinch, but ideally I someone upload the full table of AF measurements (there's about 120). Could this full table be put on the SD card and subtracted from measurements?
 

On Tue, Mar 4, 2025 at 06:33 AM, Magne Lauritzen wrote:
Thank you for the suggestion. Is the trace limited to 8 points linearly interpolated?
Yes
This may work fine in a pinch, but ideally I someone upload the full table of AF measurements (there's about 120). Could this full table be put on the SD card and subtracted from measurements?
Yes, Suggest to measure the exact frequency range of the antenna and store the trace on the SD, move it to a computer and edit the 450 values to reflect the antenna, move back to tinySA and load the trace from SD and subtract from active trace
?
--
Designer of the tinySA
For more info go to

 

You can enter the AFs and readings from the SA into separate columns within EXCEL and let that app do the arithmetic in a third column.? In addition, you could have EXCEL plot that corrected data with radiated emission limit lines.?

Dave - W?LEV

On Tue, Mar 4, 2025 at 3:02?PM Erik Kaashoek via <erik=[email protected]> wrote:
On Tue, Mar 4, 2025 at 06:33 AM, Magne Lauritzen wrote:
Thank you for the suggestion. Is the trace limited to 8 points linearly interpolated?
Yes
This may work fine in a pinch, but ideally I someone upload the full table of AF measurements (there's about 120). Could this full table be put on the SD card and subtracted from measurements?
Yes, Suggest to measure the exact frequency range of the antenna and store the trace on the SD, move it to a computer and edit the 450 values to reflect the antenna, move back to tinySA and load the trace from SD and subtract from active trace
?
--
Designer of the tinySA
For more info go to



--
Dave - W?LEV
 

That's great to hear. The application of AF was the only outstanding uncertainty I had about the TinySA before I buy it.
 

Once you have worked out how to do it and have some measurements it would be nice if you could share some experiences as this is for sure a more advanced topic for many users
--
Designer of the tinySA
For more info go to

 

at 77.5 years, I learn something new everyday!? But this topic makes my head hurt (in a good way)!? Thanks folks!
--
Dan Mail Photo.jpg
Dan N1DH
Middleboro MA
 

Welcome to the elete "Old Fossil Club", Dan.? I'm 78.25 years "wise".?

Dave - W?LEV

On Wed, Mar 5, 2025 at 12:39?PM Dan Heather via <jdanheather=[email protected]> wrote:
at 77.5 years, I learn something new everyday!? But this topic makes my head hurt (in a good way)!? Thanks folks!
--
Dan Mail Photo.jpg
Dan N1DH
Middleboro MA



--
Dave - W?LEV
 

Just a matter of spectral interpretation: Some time ago, I recognized that tinySA ultra offers a quasi peak display. But what I saw was something like attack and decay effects so to say over the time axis, or said in another way: along the frequency axis. But that's not quasi peak of a single frequency that's staying - let's say one second before the next frequency is swept up. But perhaps you'd get a reasonable result when the sweep is done as slowly as in standard tests.

Rob


On Tue, 04 Mar 2025 14:51:16 +0100, Magne Lauritzen via groups.io <mag.lauritzen@...> wrote:

Good day,
?
I would like to know whether I can apply the Antenna Factor (AF) for my calibrated biconical antenna to measurements being made by the TinySA Ultra. Antenna theory refresher: The AF is a value that lets you go from measured intensity to actual E-field intensity. It is critical when doing compliance testing of radiated emissions.
?
If the AF was just a single value I could apply it to the TinySA settings as a pretend attenuator between the antenna and the TinySA. But the AF of my antenna is highly frequency-dependent, varying by over 20dB over my frequency range of interest.?
 

Yes, you could so long as you are at or below -30 dBm on the TinySA (I believe the spec is -26 dBm).? Add 107 you dBm to get dBuV.? Or more rigorously:

? ?? dBV = dBm + 10 lob[Z]?+ 90 ?

HOWEVER, the reg. testing requires you to search vertically in both vertical and horizontal polarizations for the maximum of at least 6 of the highest "quick-look" frequencies.? The "quick-0look" search should include measuring in both vertical and horizontal poilarizatioins at every 22.5-degrees of rotation of the DUT.

In addition, a good conductive "ground plane" (and it REALLY IS a GROUND PLANE - REFLECTIVE)? be present totally between the DUT and the antenna.? Without that, you can not make good regulatory judgement in a pre-compliance setup.

Dave - W?LEV?

Virus-free.


On Wed, Mar 5, 2025 at 6:57?PM R. Maris via <spin.in.het=[email protected]> wrote:
Just a matter of spectral interpretation: Some time ago, I recognized that tinySA ultra offers a quasi peak display. But what I saw was something like attack and decay effects so to say over the time axis, or said in another way: along the frequency axis. But that's not quasi peak of a single frequency that's staying - let's say one second before the next frequency is swept up. But perhaps you'd get a reasonable result when the sweep is done as slowly as in standard tests.

Rob


On Tue, 04 Mar 2025 14:51:16 +0100, Magne Lauritzen via <mag.lauritzen=[email protected]> wrote:

Good day,
?
I would like to know whether I can apply the Antenna Factor (AF) for my calibrated biconical antenna to measurements being made by the TinySA Ultra. Antenna theory refresher: The AF is a value that lets you go from measured intensity to actual E-field intensity. It is critical when doing compliance testing of radiated emissions.
?
If the AF was just a single value I could apply it to the TinySA settings as a pretend attenuator between the antenna and the TinySA. But the AF of my antenna is highly frequency-dependent, varying by over 20dB over my frequency range of interest.?




--
Dave - W?LEV
 

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Gotcha ya beat, Dave, I was born the day before Ruzevult DIED. So that puts me up on the stack.

Mike C. Sand Mtn GA


On 3/5/2025 11:12 AM, W0LEV via groups.io wrote:

Welcome to the elete "Old Fossil Club", Dan.? I'm 78.25 years "wise".?

Dave - W?LEV

On Wed, Mar 5, 2025 at 12:39?PM Dan Heather via <jdanheather=[email protected]> wrote:
at 77.5 years, I learn something new everyday!? But this topic makes my head hurt (in a good way)!? Thanks folks!
--
Dan Mail Photo.jpg
Dan N1DH
Middleboro MA


--
Dave - W?LEV

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