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Antenna/Network Analyzer
Has anyone here built a GOOD antenna/network analyzer?
From what I can determine, the MFJ stuff doesn't resolve the sign of reactances, nor does it have a computer interface. I was looking at Analog Devices' AD8302 IC (http://www.analog.com) for this application. This is a single-chip device that measures the gain and phase difference between 2 RF inputs up to 2.7 GHZ with very high accuracy. It occurred to me that this chip, together with a PIC that has A-D conversion, and a computer-controlled station transceiver, could form the basis for a very nice programmable antenna/network analyzer that would run rings around the MFJ units. Comments? Joe W3JDR |
W3JDR wrote: Has anyone here built a GOOD antenna/network analyzer? From what I can determine, the MFJ stuff doesn't resolve the sign of reactances, nor does it have a computer interface. I was looking at Analog Devices' AD8302 IC (http://www.analog.com) for this application. This is a single-chip device that measures the gain and phase difference between 2 RF inputs up to 2.7 GHZ with very high accuracy. It occurred to me that this chip, together with a PIC that has A-D conversion, and a computer-controlled station transceiver, could form the basis for a very nice programmable antenna/network analyzer that would run rings around the MFJ units. Comments? Joe W3JDR Hi Joe, Look at: http://www.njqrp.org/antanal/ Perhaps your IC could be combined with this controller. Dale W4OP |
W3JDR wrote: Has anyone here built a GOOD antenna/network analyzer? From what I can determine, the MFJ stuff doesn't resolve the sign of reactances, nor does it have a computer interface. I was looking at Analog Devices' AD8302 IC (http://www.analog.com) for this application. This is a single-chip device that measures the gain and phase difference between 2 RF inputs up to 2.7 GHZ with very high accuracy. It occurred to me that this chip, together with a PIC that has A-D conversion, and a computer-controlled station transceiver, could form the basis for a very nice programmable antenna/network analyzer that would run rings around the MFJ units. Comments? Joe W3JDR Hi Joe, Look at: http://www.njqrp.org/antanal/ Perhaps your IC could be combined with this controller. Dale W4OP |
The technology has been available for several years to enable a manufacturer
to produce a reasonably priced, small, hand-held, battery-operated, antenna analyser which displays the sign of jX. But the manufacturers have not yet extracted all that's available from the market. Its too early to introduce a new model which would outclass the old. What is needed in the market is a new manufacturer who has no history to take advantage of. Chinese ? |
The technology has been available for several years to enable a manufacturer
to produce a reasonably priced, small, hand-held, battery-operated, antenna analyser which displays the sign of jX. But the manufacturers have not yet extracted all that's available from the market. Its too early to introduce a new model which would outclass the old. What is needed in the market is a new manufacturer who has no history to take advantage of. Chinese ? |
Dale,
Actually, I was thinking that the controller is a PC or laptop. It would control the station transciever as a swept low-power frequency source, and get the phase and gain readings from the PIC that would be paired with the Analog Devices part (and of course a directional coupler of some sort...even a simple bridge would suffice). This design could result in a very simple, low-cost, and powerful vector network analyzer for the average ham. Joe W3JDR "Dale Parfitt" wrote in message ... W3JDR wrote: Has anyone here built a GOOD antenna/network analyzer? From what I can determine, the MFJ stuff doesn't resolve the sign of reactances, nor does it have a computer interface. I was looking at Analog Devices' AD8302 IC (http://www.analog.com) for this application. This is a single-chip device that measures the gain and phase difference between 2 RF inputs up to 2.7 GHZ with very high accuracy. It occurred to me that this chip, together with a PIC that has A-D conversion, and a computer-controlled station transceiver, could form the basis for a very nice programmable antenna/network analyzer that would run rings around the MFJ units. Comments? Joe W3JDR Hi Joe, Look at: http://www.njqrp.org/antanal/ Perhaps your IC could be combined with this controller. Dale W4OP |
Dale,
Actually, I was thinking that the controller is a PC or laptop. It would control the station transciever as a swept low-power frequency source, and get the phase and gain readings from the PIC that would be paired with the Analog Devices part (and of course a directional coupler of some sort...even a simple bridge would suffice). This design could result in a very simple, low-cost, and powerful vector network analyzer for the average ham. Joe W3JDR "Dale Parfitt" wrote in message ... W3JDR wrote: Has anyone here built a GOOD antenna/network analyzer? From what I can determine, the MFJ stuff doesn't resolve the sign of reactances, nor does it have a computer interface. I was looking at Analog Devices' AD8302 IC (http://www.analog.com) for this application. This is a single-chip device that measures the gain and phase difference between 2 RF inputs up to 2.7 GHZ with very high accuracy. It occurred to me that this chip, together with a PIC that has A-D conversion, and a computer-controlled station transceiver, could form the basis for a very nice programmable antenna/network analyzer that would run rings around the MFJ units. Comments? Joe W3JDR Hi Joe, Look at: http://www.njqrp.org/antanal/ Perhaps your IC could be combined with this controller. Dale W4OP |
Reg,
I don't think it has much to do with planned product lifecycle...it's just inertia and complacency. Nor do I don't think there's enough volume for a "Chinese" manufacturer. I think the main reason we haven't seen something better is that it's too small a market for a startup to tackle. It's definitely a product for a tiny company. Joe W3JDR "Reg Edwards" wrote in message ... The technology has been available for several years to enable a manufacturer to produce a reasonably priced, small, hand-held, battery-operated, antenna analyser which displays the sign of jX. But the manufacturers have not yet extracted all that's available from the market. Its too early to introduce a new model which would outclass the old. What is needed in the market is a new manufacturer who has no history to take advantage of. Chinese ? |
Reg,
I don't think it has much to do with planned product lifecycle...it's just inertia and complacency. Nor do I don't think there's enough volume for a "Chinese" manufacturer. I think the main reason we haven't seen something better is that it's too small a market for a startup to tackle. It's definitely a product for a tiny company. Joe W3JDR "Reg Edwards" wrote in message ... The technology has been available for several years to enable a manufacturer to produce a reasonably priced, small, hand-held, battery-operated, antenna analyser which displays the sign of jX. But the manufacturers have not yet extracted all that's available from the market. Its too early to introduce a new model which would outclass the old. What is needed in the market is a new manufacturer who has no history to take advantage of. Chinese ? |
The chip you're looking at does have a 180 degree ambiguity unresolved.
Makes it tough to do the job you're asking of it. Wait a couple weeks and look on Google for N2PK. You'll find a real vector network analyzer good from 50 KHz to 60 MHz with narrow band application to 2 meters and 432 MHz. W4ZCB |
The chip you're looking at does have a 180 degree ambiguity unresolved.
Makes it tough to do the job you're asking of it. Wait a couple weeks and look on Google for N2PK. You'll find a real vector network analyzer good from 50 KHz to 60 MHz with narrow band application to 2 meters and 432 MHz. W4ZCB |
Harold,
The chip's phase measurement transer function has a positive slope for phase angles less than 0deg and a negative slope for phase angles greater than 0deg. So it seems to me that resolving the 180 deg ambiguity is just a matter of knowing which slope you're on. This might be done by switching in a small known reactive component and observing which direction the phase output changes. Once you know which slope you're on, I think you're home free...no?? Joe W3JDR "Harold E. Johnson" wrote in message news:Yhiab.496033$Ho3.84151@sccrnsc03... The chip you're looking at does have a 180 degree ambiguity unresolved. Makes it tough to do the job you're asking of it. Wait a couple weeks and look on Google for N2PK. You'll find a real vector network analyzer good from 50 KHz to 60 MHz with narrow band application to 2 meters and 432 MHz. W4ZCB |
Harold,
The chip's phase measurement transer function has a positive slope for phase angles less than 0deg and a negative slope for phase angles greater than 0deg. So it seems to me that resolving the 180 deg ambiguity is just a matter of knowing which slope you're on. This might be done by switching in a small known reactive component and observing which direction the phase output changes. Once you know which slope you're on, I think you're home free...no?? Joe W3JDR "Harold E. Johnson" wrote in message news:Yhiab.496033$Ho3.84151@sccrnsc03... The chip you're looking at does have a 180 degree ambiguity unresolved. Makes it tough to do the job you're asking of it. Wait a couple weeks and look on Google for N2PK. You'll find a real vector network analyzer good from 50 KHz to 60 MHz with narrow band application to 2 meters and 432 MHz. W4ZCB |
The chip's phase measurement transer function has a positive slope for phase angles less than 0deg and a negative slope for phase angles greater than 0deg. So it seems to me that resolving the 180 deg ambiguity is just a matter of knowing which slope you're on. This might be done by switching in a small known reactive component and observing which direction the phase output changes. Once you know which slope you're on, I think you're home free...no?? Do it the way you want to. W4ZCB |
The chip's phase measurement transer function has a positive slope for phase angles less than 0deg and a negative slope for phase angles greater than 0deg. So it seems to me that resolving the 180 deg ambiguity is just a matter of knowing which slope you're on. This might be done by switching in a small known reactive component and observing which direction the phase output changes. Once you know which slope you're on, I think you're home free...no?? Do it the way you want to. W4ZCB |
Do it the way you want to.
Harold, I'm puzzled by your reply. Does it mean that you agree, or that you disagree, or that you're just brushing me off? If it's the latter, I can accept that too...I'm just looking for a sincere dialog about an idea. Joe W3JDR |
Do it the way you want to.
Harold, I'm puzzled by your reply. Does it mean that you agree, or that you disagree, or that you're just brushing me off? If it's the latter, I can accept that too...I'm just looking for a sincere dialog about an idea. Joe W3JDR |
All the analyzers I have considered have always been to inaccurate. They
sure may work on the DC bands below 30MHz where people think an antenna is good if the SWR is below 3. This IC seem promising. Together with a small MCU and AD and some flash memory you might be able to build a really good instrument that could beat everything on the market. Does anyone know a source for these chipts whithin the EU? I have some directional couplers without detectors that could easily be combined with this chip. Your Idea to use a PC to control the radio as a source seem interesting. The only drawback would be the size of all the stuff you need to bring into the garden when measuring. Perhaps a modular design. a) Optional RF-circuit (directional couplers) different for different bands to increase accuracy. b) Detector device (AD-chip, small controller with calibration data) c) Optional display for computerless operation d) Optional signal source for rig-less operation. /Leif |
All the analyzers I have considered have always been to inaccurate. They
sure may work on the DC bands below 30MHz where people think an antenna is good if the SWR is below 3. This IC seem promising. Together with a small MCU and AD and some flash memory you might be able to build a really good instrument that could beat everything on the market. Does anyone know a source for these chipts whithin the EU? I have some directional couplers without detectors that could easily be combined with this chip. Your Idea to use a PC to control the radio as a source seem interesting. The only drawback would be the size of all the stuff you need to bring into the garden when measuring. Perhaps a modular design. a) Optional RF-circuit (directional couplers) different for different bands to increase accuracy. b) Detector device (AD-chip, small controller with calibration data) c) Optional display for computerless operation d) Optional signal source for rig-less operation. /Leif |
Leif,
Does anyone know a source for these chipts whithin the EU? I believe you can purchase them from the Analog Devices Web site. Don't know if that works outside the US though. I have some directional couplers without detectors that could easily be combined with this chip. Do you really need a directional coupler? How about just driving the load through a known resistor and measuring the voltage & phase shift across the unknown? Your idea to use a PC to control the radio as a source seem interesting. The only drawback would be the size of all the stuff you need to bring into the garden when measuring. I suggested the station rig as a source because it already has a programmable frequency generator for any frequency the ham is likely to need to measure...why reinvent it? On the other hand, it's easy these days to build a DDS frequency source that works into the VHF range. Used laptop PC's are plentiful and cheap, and have great computational and display facilities. I was thinking of a small module that works with the station PC or a laptop. Joe W3JDR |
Leif,
Does anyone know a source for these chipts whithin the EU? I believe you can purchase them from the Analog Devices Web site. Don't know if that works outside the US though. I have some directional couplers without detectors that could easily be combined with this chip. Do you really need a directional coupler? How about just driving the load through a known resistor and measuring the voltage & phase shift across the unknown? Your idea to use a PC to control the radio as a source seem interesting. The only drawback would be the size of all the stuff you need to bring into the garden when measuring. I suggested the station rig as a source because it already has a programmable frequency generator for any frequency the ham is likely to need to measure...why reinvent it? On the other hand, it's easy these days to build a DDS frequency source that works into the VHF range. Used laptop PC's are plentiful and cheap, and have great computational and display facilities. I was thinking of a small module that works with the station PC or a laptop. Joe W3JDR |
The chip's phase measurement transer function has a positive slope for phase
angles less than 0deg and a negative slope for phase angles greater than 0deg. So it seems to me that resolving the 180 deg ambiguity is just a matter of knowing which slope you're on. This might be done by switching in a small known reactive component You can do this with an MFJ or any other analyzer to resolve the sign ambiguity of X. Switch in small known reactance, see which way X goes. Also, hooking a computer interface to an MFJ would probably not be that much more difficult than interfacing with the AD chip. So, no I don't think this would run rings around an MFJ. However, if you do go this route, I would be very interested in how it turns out. 73 Gary N4AST |
The chip's phase measurement transer function has a positive slope for phase
angles less than 0deg and a negative slope for phase angles greater than 0deg. So it seems to me that resolving the 180 deg ambiguity is just a matter of knowing which slope you're on. This might be done by switching in a small known reactive component You can do this with an MFJ or any other analyzer to resolve the sign ambiguity of X. Switch in small known reactance, see which way X goes. Also, hooking a computer interface to an MFJ would probably not be that much more difficult than interfacing with the AD chip. So, no I don't think this would run rings around an MFJ. However, if you do go this route, I would be very interested in how it turns out. 73 Gary N4AST |
In article ,
says... Do it the way you want to. Harold, I'm puzzled by your reply. Does it mean that you agree, or that you disagree, or that you're just brushing me off? If it's the latter, I can accept that too...I'm just looking for a sincere dialog about an idea. Who knows what he meant by that, but the idea of using a "line stretching" hack to resolve the phase ambiguity sounds like a great one to me. I'd definitely be up for building a VNA that has decent frequency coverage and that's PC-driven. I'll take a gander at the AD8302's specs first chance I get and see how it looks! -- jm ------------------------------------------------------ http://www.qsl.net/ke5fx Note: My E-mail address has been altered to avoid spam ------------------------------------------------------ |
I'm puzzled by your reply. Does it mean that you agree, or that you disagree, or that you're just brushing me off? If it's the latter, I can accept that too...I'm just looking for a sincere dialog about an idea. Joe W3JDR I'm just brushing you off. I wrote to let you know of another avenue to do the job you wish to do where someone else has invested a tremendous amount of professional work in both the hardware and software. It will be available on the Internet in a week or so. (Several of us have enjoyed the end product as a Beta test group for something over a year.) I don't have any time or interest in participating in a sincere dialog. Regards W4ZCB |
I'm puzzled by your reply. Does it mean that you agree, or that you disagree, or that you're just brushing me off? If it's the latter, I can accept that too...I'm just looking for a sincere dialog about an idea. Joe W3JDR I'm just brushing you off. I wrote to let you know of another avenue to do the job you wish to do where someone else has invested a tremendous amount of professional work in both the hardware and software. It will be available on the Internet in a week or so. (Several of us have enjoyed the end product as a Beta test group for something over a year.) I don't have any time or interest in participating in a sincere dialog. Regards W4ZCB |
Well, I guess that settles that.
The definitive work has been done and there's no room for improvement or any sense in discussing it further. Thanks for your help Joe "Harold E. Johnson" wrote in message news:Ierab.505021$YN5.337471@sccrnsc01... I'm puzzled by your reply. Does it mean that you agree, or that you disagree, or that you're just brushing me off? If it's the latter, I can accept that too...I'm just looking for a sincere dialog about an idea. Joe W3JDR I'm just brushing you off. I wrote to let you know of another avenue to do the job you wish to do where someone else has invested a tremendous amount of professional work in both the hardware and software. It will be available on the Internet in a week or so. (Several of us have enjoyed the end product as a Beta test group for something over a year.) I don't have any time or interest in participating in a sincere dialog. Regards W4ZCB |
Well, I guess that settles that.
The definitive work has been done and there's no room for improvement or any sense in discussing it further. Thanks for your help Joe "Harold E. Johnson" wrote in message news:Ierab.505021$YN5.337471@sccrnsc01... I'm puzzled by your reply. Does it mean that you agree, or that you disagree, or that you're just brushing me off? If it's the latter, I can accept that too...I'm just looking for a sincere dialog about an idea. Joe W3JDR I'm just brushing you off. I wrote to let you know of another avenue to do the job you wish to do where someone else has invested a tremendous amount of professional work in both the hardware and software. It will be available on the Internet in a week or so. (Several of us have enjoyed the end product as a Beta test group for something over a year.) I don't have any time or interest in participating in a sincere dialog. Regards W4ZCB |
I'm just brushing you off. I wrote to let you know of another avenue to do the job you wish to do where someone else has invested a tremendous amount of professional work in both the hardware and software. It will be available on the Internet in a week or so. (Several of us have enjoyed the end product as a Beta test group for something over a year.) I don't have any time or interest in participating in a sincere dialog. Regards W4ZCB Hi Harold, I well recall Paul's wattmeter- well ( or even way) beyond what others had done- the engineering and documentation was superb. Looking forward to his work on the VNR. I am not far from you- near Cashiers on Lake Glenville. Dale W4OP |
I'm just brushing you off. I wrote to let you know of another avenue to do the job you wish to do where someone else has invested a tremendous amount of professional work in both the hardware and software. It will be available on the Internet in a week or so. (Several of us have enjoyed the end product as a Beta test group for something over a year.) I don't have any time or interest in participating in a sincere dialog. Regards W4ZCB Hi Harold, I well recall Paul's wattmeter- well ( or even way) beyond what others had done- the engineering and documentation was superb. Looking forward to his work on the VNR. I am not far from you- near Cashiers on Lake Glenville. Dale W4OP |
I well recall Paul's wattmeter- well ( or even way) beyond what others had
done- the engineering and documentation was superb. Looking forward to his work on the VNR. I am not far from you- near Cashiers on Lake Glenville. Dale W4OP Hi Dale, I had no idea that you were that close. Been to Glenville many times. Why don't you come over on the first Wednesday of any month for our QCWA lunch. We have a very active group and actually have two meetings a month, but the first one always has an interesting program. If it poses a problem doing it in one day, We have a great guest apartment and I'd put you up for a Tuesday night sort of thing. You can even play with my STAR. A little DSP transceiver that Peter Rhodes developed. 160-10 with superb characteristics. There are 9 of those finished now, with another half dozen in various stages of completion just in the Beta group. I have no idea how many more are being built as the project continues to evolve in Radio Communications. If you liked Paul's wattmeter, you'll be blown away with what he's done with the VNA. Documentation itself is in 3 parts and looks like a doctoral dissertation. Both Paul and Bill Carver were here last month (Wish I had known you were this close! We met Alan Victor and Jim Scarlett and his son at Shelby for lunch) and brought their VNA's along for a round robin test. Under 1 percent variations on the Q of a test crystal between the units. He's added software to make it perform a half dozen other tasks, Transmission, Reflection, Group delay and some real time stuff. I've junked my dual crystal oscillators in the quad shield for Ip3 tests, the VNA does it on ANY frequency. A real "Lab in a Box". I think I've run the antenna characteristics on everybody's antennas within a 10 mile radius. Regards W4ZCB |
I well recall Paul's wattmeter- well ( or even way) beyond what others had
done- the engineering and documentation was superb. Looking forward to his work on the VNR. I am not far from you- near Cashiers on Lake Glenville. Dale W4OP Hi Dale, I had no idea that you were that close. Been to Glenville many times. Why don't you come over on the first Wednesday of any month for our QCWA lunch. We have a very active group and actually have two meetings a month, but the first one always has an interesting program. If it poses a problem doing it in one day, We have a great guest apartment and I'd put you up for a Tuesday night sort of thing. You can even play with my STAR. A little DSP transceiver that Peter Rhodes developed. 160-10 with superb characteristics. There are 9 of those finished now, with another half dozen in various stages of completion just in the Beta group. I have no idea how many more are being built as the project continues to evolve in Radio Communications. If you liked Paul's wattmeter, you'll be blown away with what he's done with the VNA. Documentation itself is in 3 parts and looks like a doctoral dissertation. Both Paul and Bill Carver were here last month (Wish I had known you were this close! We met Alan Victor and Jim Scarlett and his son at Shelby for lunch) and brought their VNA's along for a round robin test. Under 1 percent variations on the Q of a test crystal between the units. He's added software to make it perform a half dozen other tasks, Transmission, Reflection, Group delay and some real time stuff. I've junked my dual crystal oscillators in the quad shield for Ip3 tests, the VNA does it on ANY frequency. A real "Lab in a Box". I think I've run the antenna characteristics on everybody's antennas within a 10 mile radius. Regards W4ZCB |
Hi, all concerned:
Everybody wants to do it in software ;o) Telescoping brass tubes from hobby sources, or telescoping aluminum tubes from eg Texas Towers, can be used to build physical line-stretchers. Put the movable parts in a trough say of copper or aluminum gutter for unbalanced apps. Plan the device parts carefully, and near-50-ohm surge impedance can be had by purists and others. 73, Dave, N3HE "John Miles" wrote in message ... In article , says... Do it the way you want to. Harold, I'm puzzled by your reply. Does it mean that you agree, or that you disagree, or that you're just brushing me off? If it's the latter, I can accept that too...I'm just looking for a sincere dialog about an idea. Who knows what he meant by that, but the idea of using a "line stretching" hack to resolve the phase ambiguity sounds like a great one SNIP |
Hi, all concerned:
Everybody wants to do it in software ;o) Telescoping brass tubes from hobby sources, or telescoping aluminum tubes from eg Texas Towers, can be used to build physical line-stretchers. Put the movable parts in a trough say of copper or aluminum gutter for unbalanced apps. Plan the device parts carefully, and near-50-ohm surge impedance can be had by purists and others. 73, Dave, N3HE "John Miles" wrote in message ... In article , says... Do it the way you want to. Harold, I'm puzzled by your reply. Does it mean that you agree, or that you disagree, or that you're just brushing me off? If it's the latter, I can accept that too...I'm just looking for a sincere dialog about an idea. Who knows what he meant by that, but the idea of using a "line stretching" hack to resolve the phase ambiguity sounds like a great one SNIP |
In article Ierab.505021$YN5.337471@sccrnsc01, says...
I'm puzzled by your reply. Does it mean that you agree, or that you disagree, or that you're just brushing me off? If it's the latter, I can accept that too...I'm just looking for a sincere dialog about an idea. Joe W3JDR I'm just brushing you off. I wrote to let you know of another avenue to do the job you wish to do where someone else has invested a tremendous amount of professional work in both the hardware and software. It will be available on the Internet in a week or so. (Several of us have enjoyed the end product as a Beta test group for something over a year.) I don't have any time or interest in participating in a sincere dialog. Followups set to rec.radio.amateur.equipment, since by your own admission your post is off-topic for this group. -- jm ------------------------------------------------------ http://www.qsl.net/ke5fx Note: My E-mail address has been altered to avoid spam ------------------------------------------------------ |
In article Ierab.505021$YN5.337471@sccrnsc01, says...
I'm puzzled by your reply. Does it mean that you agree, or that you disagree, or that you're just brushing me off? If it's the latter, I can accept that too...I'm just looking for a sincere dialog about an idea. Joe W3JDR I'm just brushing you off. I wrote to let you know of another avenue to do the job you wish to do where someone else has invested a tremendous amount of professional work in both the hardware and software. It will be available on the Internet in a week or so. (Several of us have enjoyed the end product as a Beta test group for something over a year.) I don't have any time or interest in participating in a sincere dialog. Followups set to rec.radio.amateur.equipment, since by your own admission your post is off-topic for this group. -- jm ------------------------------------------------------ http://www.qsl.net/ke5fx Note: My E-mail address has been altered to avoid spam ------------------------------------------------------ |
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