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Diane BONKOUNGOU
Hello,
Hi, I am a beginner in antenna design and tuning.
I want my antenna to have a resonant frequency of 2.45GHz for low-energy Bluetooth communication.
And I want to know what to consider for the matching process.
I have made some measurements with Nanovna of my antenna. I have a resonance frequency of 2.28GHz and at this frequency, I have an impedance of 47.8-7.06j. Can I take the value of this impedance at this frequency for the matching process or do I have to take the value of impedance at 2.45GHz?
Where to take the value of impedance for tuning?
Thanks.
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Hi Diane,
In my opinion you should tune to the lowest SWR or highest Return Loss at the design frequency you want. Lowest SWR at the design frequency will give you the least reflected power.
So, the first step I do is to get the SWR to the lowest you can by trimming or lengthening each siode of the dipole and equal amount. Don't forget to consider a common mode choke to reduce non-differential current on your antenna. Possibly a tiny ferrite core near the dipole connections. You can check this with your VNA.
If the SWR measures higher, say, at say, 2.45 GHz than at 2.55 GHz then you need to add a tiny length to each of the dipole ends and recheck. If you have lengthened it the SWR should have dropped a little at 2.45 GHz. This is a trial and error method. Take tiny trimming steps on such a short antenna.
Unless you are a whiz at Smith Charts I would use the SIMSMITH program for matching. Play around with different configurations with two objectives in mind: Get a close match and get the Q where you want it. You may want a very high Q for a fixed frequency. There are no hard and fast rules for this and the different matching configurations (Pi, T, etc.)
I strongly suggest you watch some of W2AEW's great videos on antenna matching. A 20 meter antenna follows the same physics as a 2 GHz antenna. The Youtube video below is on antenna matching using the nanoVNA but he has several others dealing with types of matching pros and cons.
Good luck,
Hank
On Fri, Jul 22, 2022 at 8:37 AM Diane BONKOUNGOU < dianebonk2@...> wrote: Hello,
Hi, I am a beginner in antenna design and tuning.
I want my antenna to have a resonant frequency of 2.45GHz for low-energy Bluetooth communication.
And I want to know what to consider for the matching process.
I have made some measurements with Nanovna of my antenna. I have a resonance frequency of 2.28GHz and at this frequency, I have an impedance of 47.8-7.06j. Can I take the value of this impedance at this frequency for the matching process or do I have to take the value of impedance at 2.45GHz?
Where to take the value of impedance for tuning?
Thanks.
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Hi. 2.28 GHz resonance do not matter. Only means you are close the matching @ 2.45 GHz Take impedance and values on 2.45 GHz. And cut the antenna. elements Any way, If you have a return loss in 2.45 GHz around 10 dB is ok for low power . Or try to get Return loss better than 15 dB (1.43 SWR) by shortening your antenna 😊 73 CT4BB Carlos De: miniVNA@groups.io <miniVNA@groups.io> Em Nome De Diane BONKOUNGOU
Enviada: 22 de julho de 2022 12:35
Para: miniVNA@groups.io
Assunto: [miniVNA] At which point do we take the value of impedance to tune an antenna? Hi, I am a beginner in antenna design and tuning. I want my antenna to have a resonant frequency of 2.45GHz for low-energy Bluetooth communication. And I want to know what to consider for the matching process. I have made some measurements with Nanovna of my antenna. I have a resonance frequency of 2.28GHz and at this frequency, I have an impedance of 47.8-7.06j. Can I take the value of this impedance at this frequency for the matching process or do I have to take the value of impedance at 2.45GHz? Where to take the value of impedance for tuning?
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Your measurements at 2.28 GHz are excellent for that frequency. A normal rule of thumb for acceptable VSWR is under 1.5. It appears you need only to shorten your antenna a small amount which should be by ((2.45-2.28) / 2.45) * 100%. If you are lucky, the new VSWR will be just as good. You first cut should be less so as not to overshoot your goal.
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All,
Very good explanation by Hank. However, how do we know that she is working on a dipole?
Peace,
Hi Diane,
In my opinion you should tune to the lowest SWR or highest Return Loss at the design frequency you want. Lowest SWR at the design frequency will give you the least reflected power.
So, the first step I do is to get the SWR to the lowest you can by trimming or lengthening each siode of the dipole and equal amount. Don't forget to consider a common mode choke to reduce non-differential current on your antenna. Possibly a tiny ferrite core near the dipole connections. You can check this with your VNA.
If the SWR measures higher, say, at say, 2.45 GHz than at 2.55 GHz then you need to add a tiny length to each of the dipole ends and recheck. If you have lengthened it the SWR should have dropped a little at 2.45 GHz. This is a trial and error method. Take tiny trimming steps on such a short antenna.
Unless you are a whiz at Smith Charts I would use the SIMSMITH program for matching. Play around with different configurations with two objectives in mind: Get a close match and get the Q where you want it. You may want a very high Q for a fixed frequency. There are no hard and fast rules for this and the different matching configurations (Pi, T, etc.)
I strongly suggest you watch some of W2AEW's great videos on antenna matching. A 20 meter antenna follows the same physics as a 2 GHz antenna. The Youtube video below is on antenna matching using the nanoVNA but he has several others dealing with types of matching pros and cons.
Good luck,
Hank
On Fri, Jul 22, 2022 at 8:37 AM Diane BONKOUNGOU < dianebonk2@...> wrote: Hello,
Hi, I am a beginner in antenna design and tuning.
I want my antenna to have a resonant frequency of 2.45GHz for low-energy Bluetooth communication.
And I want to know what to consider for the matching process.
I have made some measurements with Nanovna of my antenna. I have a resonance frequency of 2.28GHz and at this frequency, I have an impedance of 47.8-7.06j. Can I take the value of this impedance at this frequency for the matching process or do I have to take the value of impedance at 2.45GHz?
Where to take the value of impedance for tuning?
Thanks.
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Thanks. I just made the guess that, being new to antenna design, her design was basically a microstrip dipole. Or, possibly a microstrip quarter wave ground plane which is a little harder to design and tune. Tuning a microstrip antenna can be a pain with all the surrounding close quarter considerations.
Hopefully she has read some of the excellent and easy to understand articles on the Internet regarding Blue Tooth antenna design. Two of the best I have found using Google search are TI's "AN-1811 Bluetooth Antenna Design" and "BLE Antenna Design Guide". There are many other helpful articles on Blue Tooth ISM band antennas on the net.
Thanks again for your email.
Hank
All,
Very good explanation by Hank. However, how do we know that she is working on a dipole?
Peace, Hi Diane,
In my opinion you should tune to the lowest SWR or highest Return Loss at the design frequency you want. Lowest SWR at the design frequency will give you the least reflected power.
So, the first step I do is to get the SWR to the lowest you can by trimming or lengthening each siode of the dipole and equal amount. Don't forget to consider a common mode choke to reduce non-differential current on your antenna. Possibly a tiny ferrite core near the dipole connections. You can check this with your VNA.
If the SWR measures higher, say, at say, 2.45 GHz than at 2.55 GHz then you need to add a tiny length to each of the dipole ends and recheck. If you have lengthened it the SWR should have dropped a little at 2.45 GHz. This is a trial and error method. Take tiny trimming steps on such a short antenna.
Unless you are a whiz at Smith Charts I would use the SIMSMITH program for matching. Play around with different configurations with two objectives in mind: Get a close match and get the Q where you want it. You may want a very high Q for a fixed frequency. There are no hard and fast rules for this and the different matching configurations (Pi, T, etc.)
I strongly suggest you watch some of W2AEW's great videos on antenna matching. A 20 meter antenna follows the same physics as a 2 GHz antenna. The Youtube video below is on antenna matching using the nanoVNA but he has several others dealing with types of matching pros and cons.
Good luck,
Hank
On Fri, Jul 22, 2022 at 8:37 AM Diane BONKOUNGOU < dianebonk2@...> wrote: Hello,
Hi, I am a beginner in antenna design and tuning.
I want my antenna to have a resonant frequency of 2.45GHz for low-energy Bluetooth communication.
And I want to know what to consider for the matching process.
I have made some measurements with Nanovna of my antenna. I have a resonance frequency of 2.28GHz and at this frequency, I have an impedance of 47.8-7.06j. Can I take the value of this impedance at this frequency for the matching process or do I have to take the value of impedance at 2.45GHz?
Where to take the value of impedance for tuning?
Thanks.
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If possible calibrate your nanoVNA to the reference plane of the antenna feedpoint.
On Jul 23, 2022, at 3:02 AM, Jay Zebryk <jay.zebryk@...> wrote:
All,
Very good explanation by Hank. However, how do we know that she is working on a dipole?
Peace, Hi Diane,
In my opinion you should tune to the lowest SWR or highest Return Loss at the design frequency you want. Lowest SWR at the design frequency will give you the least reflected power.
So, the first step I do is to get the SWR to the lowest you can by trimming or lengthening each siode of the dipole and equal amount. Don't forget to consider a common mode choke to reduce non-differential current on your antenna. Possibly a tiny ferrite core near the dipole connections. You can check this with your VNA.
If the SWR measures higher, say, at say, 2.45 GHz than at 2.55 GHz then you need to add a tiny length to each of the dipole ends and recheck. If you have lengthened it the SWR should have dropped a little at 2.45 GHz. This is a trial and error method. Take tiny trimming steps on such a short antenna.
Unless you are a whiz at Smith Charts I would use the SIMSMITH program for matching. Play around with different configurations with two objectives in mind: Get a close match and get the Q where you want it. You may want a very high Q for a fixed frequency. There are no hard and fast rules for this and the different matching configurations (Pi, T, etc.)
I strongly suggest you watch some of W2AEW's great videos on antenna matching. A 20 meter antenna follows the same physics as a 2 GHz antenna. The Youtube video below is on antenna matching using the nanoVNA but he has several others dealing with types of matching pros and cons.
Good luck,
Hank
On Fri, Jul 22, 2022 at 8:37 AM Diane BONKOUNGOU < dianebonk2@...> wrote: Hello,
Hi, I am a beginner in antenna design and tuning.
I want my antenna to have a resonant frequency of 2.45GHz for low-energy Bluetooth communication.
And I want to know what to consider for the matching process.
I have made some measurements with Nanovna of my antenna. I have a resonance frequency of 2.28GHz and at this frequency, I have an impedance of 47.8-7.06j. Can I take the value of this impedance at this frequency for the matching process or do I have to take the value of impedance at 2.45GHz?
Where to take the value of impedance for tuning?
Thanks.
|
|
|
Diane BONKOUNGOU
Thank you all for your answer. I took the value of impedance at 2.45GHz as you advised me for the matching process. I will use the SimSmith table to find the value of inductance and capacitance for the matching process. I am using a PCB trace antenna. My question regarding Simsmith and other online calculators for the matching process that exists is: Is it important to take into account the frequency and quality factor of the inductance and capacitance? I have found that it is not necessary to have these values when finding the value of capacitance and inductance because it can complicate the calculation process and make it difficult to find the value of capacitance and inductance. This question is due to the fact that I saw in the inductance and capacitance data sheet that there is a curve of impedance and quality factor versus frequency.
To get started on my project, I read a lot of literature on PCB trace antenna design from Texas Instrument and Cypress. There are already a few designs out there but I need to make another design with a small size so that the shape of my antenna is not common with the inverted F-antenna or the meander antenna. I based my design on the fact that it is the length of the antenna that counts and I hope it will work. For 2.45GHz a lambda/4 antenna length should be about 30mm.
Thanks
If possible calibrate your nanoVNA to the reference plane of the antenna feedpoint. All,
Very good explanation by Hank. However, how do we know that she is working on a dipole?
Peace, Hi Diane,
In my opinion you should tune to the lowest SWR or highest Return Loss at the design frequency you want. Lowest SWR at the design frequency will give you the least reflected power.
So, the first step I do is to get the SWR to the lowest you can by trimming or lengthening each siode of the dipole and equal amount. Don't forget to consider a common mode choke to reduce non-differential current on your antenna. Possibly a tiny ferrite core near the dipole connections. You can check this with your VNA.
If the SWR measures higher, say, at say, 2.45 GHz than at 2.55 GHz then you need to add a tiny length to each of the dipole ends and recheck. If you have lengthened it the SWR should have dropped a little at 2.45 GHz. This is a trial and error method. Take tiny trimming steps on such a short antenna.
Unless you are a whiz at Smith Charts I would use the SIMSMITH program for matching. Play around with different configurations with two objectives in mind: Get a close match and get the Q where you want it. You may want a very high Q for a fixed frequency. There are no hard and fast rules for this and the different matching configurations (Pi, T, etc.)
I strongly suggest you watch some of W2AEW's great videos on antenna matching. A 20 meter antenna follows the same physics as a 2 GHz antenna. The Youtube video below is on antenna matching using the nanoVNA but he has several others dealing with types of matching pros and cons.
Good luck,
Hank
On Fri, Jul 22, 2022 at 8:37 AM Diane BONKOUNGOU < dianebonk2@...> wrote: Hello,
Hi, I am a beginner in antenna design and tuning.
I want my antenna to have a resonant frequency of 2.45GHz for low-energy Bluetooth communication.
And I want to know what to consider for the matching process.
I have made some measurements with Nanovna of my antenna. I have a resonance frequency of 2.28GHz and at this frequency, I have an impedance of 47.8-7.06j. Can I take the value of this impedance at this frequency for the matching process or do I have to take the value of impedance at 2.45GHz?
Where to take the value of impedance for tuning?
Thanks.
|
|
|
Diane BONKOUNGOU
Hello, Thanks for your response I have done that first. I calibrate the NanoVNA and then I correct the delay introduced by the length of the SMA cable. Best regards
If possible calibrate your nanoVNA to the reference plane of the antenna feedpoint. All,
Very good explanation by Hank. However, how do we know that she is working on a dipole?
Peace, Hi Diane,
In my opinion you should tune to the lowest SWR or highest Return Loss at the design frequency you want. Lowest SWR at the design frequency will give you the least reflected power.
So, the first step I do is to get the SWR to the lowest you can by trimming or lengthening each siode of the dipole and equal amount. Don't forget to consider a common mode choke to reduce non-differential current on your antenna. Possibly a tiny ferrite core near the dipole connections. You can check this with your VNA.
If the SWR measures higher, say, at say, 2.45 GHz than at 2.55 GHz then you need to add a tiny length to each of the dipole ends and recheck. If you have lengthened it the SWR should have dropped a little at 2.45 GHz. This is a trial and error method. Take tiny trimming steps on such a short antenna.
Unless you are a whiz at Smith Charts I would use the SIMSMITH program for matching. Play around with different configurations with two objectives in mind: Get a close match and get the Q where you want it. You may want a very high Q for a fixed frequency. There are no hard and fast rules for this and the different matching configurations (Pi, T, etc.)
I strongly suggest you watch some of W2AEW's great videos on antenna matching. A 20 meter antenna follows the same physics as a 2 GHz antenna. The Youtube video below is on antenna matching using the nanoVNA but he has several others dealing with types of matching pros and cons.
Good luck,
Hank
On Fri, Jul 22, 2022 at 8:37 AM Diane BONKOUNGOU < dianebonk2@...> wrote: Hello,
Hi, I am a beginner in antenna design and tuning.
I want my antenna to have a resonant frequency of 2.45GHz for low-energy Bluetooth communication.
And I want to know what to consider for the matching process.
I have made some measurements with Nanovna of my antenna. I have a resonance frequency of 2.28GHz and at this frequency, I have an impedance of 47.8-7.06j. Can I take the value of this impedance at this frequency for the matching process or do I have to take the value of impedance at 2.45GHz?
Where to take the value of impedance for tuning?
Thanks.
|
|
|
Diane,
It is better to calibrate at the end of the cables rather than at the VNA and add the delay for the cables as an adjustment.
Also, there are many bad cables out there so, if you need accurate results, but the best cables you can afford.
Hank
On Mon, Aug 15, 2022 at 5:36 AM Diane BONKOUNGOU < dianebonk2@...> wrote: Hello, Thanks for your response I have done that first. I calibrate the NanoVNA and then I correct the delay introduced by the length of the SMA cable. Best regards
If possible calibrate your nanoVNA to the reference plane of the antenna feedpoint. All,
Very good explanation by Hank. However, how do we know that she is working on a dipole?
Peace, Hi Diane,
In my opinion you should tune to the lowest SWR or highest Return Loss at the design frequency you want. Lowest SWR at the design frequency will give you the least reflected power.
So, the first step I do is to get the SWR to the lowest you can by trimming or lengthening each siode of the dipole and equal amount. Don't forget to consider a common mode choke to reduce non-differential current on your antenna. Possibly a tiny ferrite core near the dipole connections. You can check this with your VNA.
If the SWR measures higher, say, at say, 2.45 GHz than at 2.55 GHz then you need to add a tiny length to each of the dipole ends and recheck. If you have lengthened it the SWR should have dropped a little at 2.45 GHz. This is a trial and error method. Take tiny trimming steps on such a short antenna.
Unless you are a whiz at Smith Charts I would use the SIMSMITH program for matching. Play around with different configurations with two objectives in mind: Get a close match and get the Q where you want it. You may want a very high Q for a fixed frequency. There are no hard and fast rules for this and the different matching configurations (Pi, T, etc.)
I strongly suggest you watch some of W2AEW's great videos on antenna matching. A 20 meter antenna follows the same physics as a 2 GHz antenna. The Youtube video below is on antenna matching using the nanoVNA but he has several others dealing with types of matching pros and cons.
Good luck,
Hank
On Fri, Jul 22, 2022 at 8:37 AM Diane BONKOUNGOU < dianebonk2@...> wrote: Hello,
Hi, I am a beginner in antenna design and tuning.
I want my antenna to have a resonant frequency of 2.45GHz for low-energy Bluetooth communication.
And I want to know what to consider for the matching process.
I have made some measurements with Nanovna of my antenna. I have a resonance frequency of 2.28GHz and at this frequency, I have an impedance of 47.8-7.06j. Can I take the value of this impedance at this frequency for the matching process or do I have to take the value of impedance at 2.45GHz?
Where to take the value of impedance for tuning?
Thanks.
|
|
|
Diane,
SimSmith Pro is a great tool for antenna design. The quality factor of inductors and capacitors is important in antenna design and that's why these are included as parameters in SimSmith. I am certainly not an expert on this but the Q factor will have a major impact on the band width and roll-off of your antenna at any frequency.
Texas Instruments has a great article on PCB antennas that discusses the importance of the Q factor and it is attached. If, for some reason, the attachment is lost, you can find it by Googling (sic) "Small Antennas Designed on Printed
Circuit Boards".
Hank
On Mon, Aug 15, 2022 at 5:36 AM Diane BONKOUNGOU < dianebonk2@...> wrote: Thank you all for your answer. I took the value of impedance at 2.45GHz as you advised me for the matching process. I will use the SimSmith table to find the value of inductance and capacitance for the matching process. I am using a PCB trace antenna. My question regarding Simsmith and other online calculators for the matching process that exists is: Is it important to take into account the frequency and quality factor of the inductance and capacitance? I have found that it is not necessary to have these values when finding the value of capacitance and inductance because it can complicate the calculation process and make it difficult to find the value of capacitance and inductance. This question is due to the fact that I saw in the inductance and capacitance data sheet that there is a curve of impedance and quality factor versus frequency.
To get started on my project, I read a lot of literature on PCB trace antenna design from Texas Instrument and Cypress. There are already a few designs out there but I need to make another design with a small size so that the shape of my antenna is not common with the inverted F-antenna or the meander antenna. I based my design on the fact that it is the length of the antenna that counts and I hope it will work. For 2.45GHz a lambda/4 antenna length should be about 30mm.
Thanks
If possible calibrate your nanoVNA to the reference plane of the antenna feedpoint. All,
Very good explanation by Hank. However, how do we know that she is working on a dipole?
Peace, Hi Diane,
In my opinion you should tune to the lowest SWR or highest Return Loss at the design frequency you want. Lowest SWR at the design frequency will give you the least reflected power.
So, the first step I do is to get the SWR to the lowest you can by trimming or lengthening each siode of the dipole and equal amount. Don't forget to consider a common mode choke to reduce non-differential current on your antenna. Possibly a tiny ferrite core near the dipole connections. You can check this with your VNA.
If the SWR measures higher, say, at say, 2.45 GHz than at 2.55 GHz then you need to add a tiny length to each of the dipole ends and recheck. If you have lengthened it the SWR should have dropped a little at 2.45 GHz. This is a trial and error method. Take tiny trimming steps on such a short antenna.
Unless you are a whiz at Smith Charts I would use the SIMSMITH program for matching. Play around with different configurations with two objectives in mind: Get a close match and get the Q where you want it. You may want a very high Q for a fixed frequency. There are no hard and fast rules for this and the different matching configurations (Pi, T, etc.)
I strongly suggest you watch some of W2AEW's great videos on antenna matching. A 20 meter antenna follows the same physics as a 2 GHz antenna. The Youtube video below is on antenna matching using the nanoVNA but he has several others dealing with types of matching pros and cons.
Good luck,
Hank
On Fri, Jul 22, 2022 at 8:37 AM Diane BONKOUNGOU < dianebonk2@...> wrote: Hello,
Hi, I am a beginner in antenna design and tuning.
I want my antenna to have a resonant frequency of 2.45GHz for low-energy Bluetooth communication.
And I want to know what to consider for the matching process.
I have made some measurements with Nanovna of my antenna. I have a resonance frequency of 2.28GHz and at this frequency, I have an impedance of 47.8-7.06j. Can I take the value of this impedance at this frequency for the matching process or do I have to take the value of impedance at 2.45GHz?
Where to take the value of impedance for tuning?
Thanks.
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