Difference between revisions of "SWR/Power meter"

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(Created page with "= Links = * [https://www.youtube.com/watch?v=byF1FLdbUiA W2AEW Tutorial about directional couplers] (Very very good) * [http://www.citrus-electronics.com/subpage.html QEX Arti...")
 
 
(3 intermediate revisions by the same user not shown)
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= Links =
 
= Links =
 
* [https://www.youtube.com/watch?v=byF1FLdbUiA W2AEW Tutorial about directional couplers] (Very very good)
 
* [https://www.youtube.com/watch?v=byF1FLdbUiA W2AEW Tutorial about directional couplers] (Very very good)
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* [http://www.analog.com/media/en/training-seminars/tutorials/MT-094.pdf Microstrip and Stripline Design ] Analog Devices Tutorial
 
* [http://www.analog.com/media/en/training-seminars/tutorials/MT-094.pdf Microstrip and Stripline Design ] Analog Devices Tutorial
 
* [http://home.arcor.de/yo4gms/Directional%20Coupler%20pa0nhc.htm Directional Couplers / SWR detectors for 145MHz - 435MHz]
 
* [http://home.arcor.de/yo4gms/Directional%20Coupler%20pa0nhc.htm Directional Couplers / SWR detectors for 145MHz - 435MHz]
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* [http://www.multek.se/engelska/engineering/pcb-structures-2/embedded-microstrip-impedance-calculator-2 Multi-Teknik Impedance calculator]
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* [http://www.qsl.net/va3iul/Microstrip%20impedance/How_to_measure_the_impedance_of_a_micro-strip_Transmission_Line.htm How to measure transmission line impedance]
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* [http://www.antenna-theory.com/tutorial/txline/transmissionline.php Introduction to transmission lines]
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* [http://www.antenna-theory.com/tutorial/smith/chart.php Smith chart tutorial]
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* [http://chemandy.com/technical-articles/single-pages/relative-dielectric-constant-method.htm Determine the dielectric constant]
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= Step 1 =
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The plan is to make a test setup, somewhat like what W2AEW did, but with an embedded microstrip design like in the QEX article. The idea is then to measure properties with my N2PK VNA. Or at least, try to.
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== Impedance ==
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So, the big problem, how wide should the traces be. According to the calculator from Multi-Teknik, referencenced in the QEX calculator, I get a width that varies a bit around 2.1mm (trace thickness = 0.035mm, h=1.6mm, total height = 3.2mm, Er=4.2...4.8).
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== Results ==
 +
After constructing the PCB, measurements indicate it works very well up to 60 MHz (the very limit of my measurement capabilities with the N2PK VNA). Coupling factor is 30dB (or should I say -30dB? idk), Directivity is another 30dB. Then, measuring at the radio club, I noticed that the directivity diminished with frequency, leaving only 12dB at 500MHz.
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Next step is measuring the impedance of the embedded microstrip lines as described [http://www.qsl.net/va3iul/Microstrip%20impedance/How_to_measure_the_impedance_of_a_micro-strip_Transmission_Line.htm here]. I know who to call for this.

Latest revision as of 16:46, 20 November 2015

Links

Step 1

The plan is to make a test setup, somewhat like what W2AEW did, but with an embedded microstrip design like in the QEX article. The idea is then to measure properties with my N2PK VNA. Or at least, try to.

Impedance

So, the big problem, how wide should the traces be. According to the calculator from Multi-Teknik, referencenced in the QEX calculator, I get a width that varies a bit around 2.1mm (trace thickness = 0.035mm, h=1.6mm, total height = 3.2mm, Er=4.2...4.8).

Results

After constructing the PCB, measurements indicate it works very well up to 60 MHz (the very limit of my measurement capabilities with the N2PK VNA). Coupling factor is 30dB (or should I say -30dB? idk), Directivity is another 30dB. Then, measuring at the radio club, I noticed that the directivity diminished with frequency, leaving only 12dB at 500MHz.

Next step is measuring the impedance of the embedded microstrip lines as described here. I know who to call for this.