I have been thinking about how i can compare vertical antennas on 11/10 meters ..back in my CB days on FM in the UK was easy as on CB there was duzerns of folk i used to talk to and being on FM mine and their signals never changed unless you changed something in fact if someone say had a mic problem and had no audio if you had an analog meter chances are you would know who it was just by thier RX signal ..now i can think of 2 ways to monitor my signal, 1 set up a radio at an elderly relative's house and have a video link over internet, to see the meter, this would be about 6 miles away ..the radio will have to be a cheap CB as it will have to be in an out building that's not practically safe or preferable but i don't know if it will be as effective the furthest i can get on my property is 200yds from my test mast now i could put put a CB 200yds away or even a field strength meter with a large antenna ..but what i am asking i want to measure low angle signal will 200yds away be far enough away to see changes ..typical thing i would be testing is say the difference between an Imax 2000 with or without ground radials or say a car antenna on a mag mount vs a stud mount or just different antenna designs
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testing 10m antennas with repeatable results
- Thread starter davev8
- Start date
To test RX put small signal generator a kilometer away or so. (TinySA)
To test TX use field strength meter, TinySA or similar.
Mike
To test TX use field strength meter, TinySA or similar.
Mike
SDR radio setup somewhere a good distance away from your antennas under test & not on a hill/higher ground with software such as anydesk to remotely view your sdr,
RSP 1a/b have a calibrated s-meter when using sdruno software,
you can do it the other way around, setup sdr at home & take your antennas out to a suitable test place,
The secret sauce for low angle signal strength is antenna height above ground & other conductive junk,
2 wavelengths to base of antenna if at all possible makes more difference than the type of antenna you use,
& never have the antenna electrically connected to a conductive mast & always use an effective choke @ or near the feedpoint,
I would take a properly installed antenna @ 2 wavelengths on lower ground over a thrown together install @ 1 wavelength to base on a hill anyday.
RSP 1a/b have a calibrated s-meter when using sdruno software,
you can do it the other way around, setup sdr at home & take your antennas out to a suitable test place,
The secret sauce for low angle signal strength is antenna height above ground & other conductive junk,
2 wavelengths to base of antenna if at all possible makes more difference than the type of antenna you use,
& never have the antenna electrically connected to a conductive mast & always use an effective choke @ or near the feedpoint,
I would take a properly installed antenna @ 2 wavelengths on lower ground over a thrown together install @ 1 wavelength to base on a hill anyday.
WebSDR?
Down here in The Netherlands there's at least 4 web SDR's I can hit from my location. That doesn't mean it is the same for you in the UK, but have a look at the Kiwi (link) and OpenWebRX (link) maps to see if there's one closeby.
There's more than those two, but it's a good start.
Down here in The Netherlands there's at least 4 web SDR's I can hit from my location. That doesn't mean it is the same for you in the UK, but have a look at the Kiwi (link) and OpenWebRX (link) maps to see if there's one closeby.
There's more than those two, but it's a good start.
My suggestion would be a modification of bob85's.
To test a mobile setup I would put up an antenna at the house attached to a usb based spectrum analyzer, then with either remote access on the computer set up or perhaps streaming to a youtube or twitch account. This would let me test in various areas and see what is going on.
If it is a base setup under test, I would map out several specific parking spots around the area various distances and directions away so that I can take my measurements and return to the same spot for comparisons after making changes to the antenna.
I suppose once you get the remote access or streaming figured out you could also just put a web cam on the radio if you don't have and don't want to get a spectrum analyzer. That being said, the spectrum analyzer would give you more accurate and, if you know what your looking at, more extensive (or perhaps I should say more complete) data.
edit---
19wrc333 lol you got in right before I did, although you are referring to existing ones and I am suggesting setting one up yourself, same basic idea...
The DB
To test a mobile setup I would put up an antenna at the house attached to a usb based spectrum analyzer, then with either remote access on the computer set up or perhaps streaming to a youtube or twitch account. This would let me test in various areas and see what is going on.
If it is a base setup under test, I would map out several specific parking spots around the area various distances and directions away so that I can take my measurements and return to the same spot for comparisons after making changes to the antenna.
I suppose once you get the remote access or streaming figured out you could also just put a web cam on the radio if you don't have and don't want to get a spectrum analyzer. That being said, the spectrum analyzer would give you more accurate and, if you know what your looking at, more extensive (or perhaps I should say more complete) data.
edit---
19wrc333 lol you got in right before I did, although you are referring to existing ones and I am suggesting setting one up yourself, same basic idea...
The DB
I have used the web sdr's,mainly on 80mtrs, The closets one to me is in Doncaster about 15 miles away,
The ones I have tried have crappy rx on 10mtrs or are too distant for 10mtrs,
This is Yorkshire we only recently left the stone age
,
I have not tried measuring the accuracy of the rsp1a with sdruno software but they claim its a calibrated s-meter but only when used with their own software,
if you only want to see any small differences with no need for measurements then a uniden export with the rf gain backed down to a s3-S4 will show exaggerated differences in signal strength.
The ones I have tried have crappy rx on 10mtrs or are too distant for 10mtrs,
This is Yorkshire we only recently left the stone age
,I have not tried measuring the accuracy of the rsp1a with sdruno software but they claim its a calibrated s-meter but only when used with their own software,
if you only want to see any small differences with no need for measurements then a uniden export with the rf gain backed down to a s3-S4 will show exaggerated differences in signal strength.
yes i understand that .it became most apparent when i was modeling a a 5/8 GP for 4m, i had modeled it at the hight it was going to be mounted i adjust the radiator length and the radials until i get the lowest take off angel which if i remember was or was close to single figures the radiator ended up just shy of the theatrical length ..so was happy ..then at last moment decided to draw the mast in ..1st thing i see was gain was up a little then i noticed the TOA was in the sky at 45 degrees..the antenna was cupuling to the mast, so put a 12 inch gap between the antenna and mast which only help a little ..i ended up shorting the radiator considerably which improved things but i never got the TOA as low as it was without the mast ..i was not relay asking how to achieve a low TOA but more can i measure the difference as close as 200 yards or will 6 miles be better..the reason i want to do this is i have started manufacturing and selling stuff on ebay i have walk up and a winch up mast posts and also a range of drive over mast supports but i want to start doing antennas, a sturdy sigma 4 and a 5/8 GP with built in choke and insulated from the mast, but my 1st product will be a universal ground plane kit that can attach to the mast of any antenna (that can make use of radials) just below the feed point ..i think a imax 2000 is crying out for one ..i have one and i put it on my 35 foot test mast that the top 2 feet is fiberglass and it did not really work the lowest SWR was 1.45 which is ok but the bandwidth was very narrow and did not hardly cover 40 CB channels so i replaced the the fiberglass rod with alloy tube the SWR came down to almost 1.1 and and a wide bandwidth..but i guess its a cloud warmer now so what i was asking is 200 yrd far enough away to register differences, or am i better of doing something 6 miles away at my elderly relatives yard
yes i am lucky to have one about 4 miles from me so think that was the easy answer ..but strangely it did not work so well ..it give signal strength in db ..but it did not make much difference what my power output was which i don't understand why.. a bird meter confirms the output of my radio now if i went from say 10watts to 20w i would expect an increase of 3db ish which is 1/2 an S point.. but it made almost no difference .it made a notable difference if i went from say 10w to 100w but nowhere near the 10db i would expect so i don't think it will register say needles thickness improvement like on an analog meter in a radio, which i want to do ..something else i don't think that SDR is very sensitive as i was talking to two others when watching the SDR on the PC ..1 guy is very close to it and it recorded a strong signal from us both, he must only be a mile away from the SDR we both give each other +30 the other guy is 10 miles away give me an s8 or s9 he did not register on the SDR 1 bit..i shall have anther look at it
yes that's what i am thinking ..maybe i waffle to much in my questions, what i am asking, i can set up something permanent ether 200yds away which is easy to do or 6 miles away what i am asking is 200 yards away to close for good results ..are small differences less likely to show
Dave, the sdr play units have a supposedly calibrated S-meter in dbm,
I don't see them as been any different to using a cheap china spectrum analyser as they both work in the same way,
if all you want is to see small changes then a 148gtldx or grant export with the rf gain backed down so your @ about s3-4 will magnify any changes, even a uniden 200 will do the same thing,
proper s-meters unlike radio s-meters won't show significant differences in antennas that are correctly installed at the same tip height
In out tests the IMAX needs isolating from the mast & the radial kit & an effective choke,
it can make a big difference to mast & coax outer braid cmc & improve signal strength,
I seem to recall The DB posting about the capacitor in the middle section bringing all radiating currents on the radiator in phase & raising the end impedance of the radiator,
unlike a regular 5/8 that has 1/8wave of unwanted radiation,
There is nothing like the difference between antennas as the makers claim IF they are all correctly isolated & choked & installed at the same tip height,
The problem is NO maker tells you how to correctly install their antennas,
some do have an edge in our tests
1st Grazioli G-MAX Beats all others but weak in high wind
2nd VECTOR 4000 style antenna adjusted for best signal about .82wave,
There are a few clones out there but imho none are mechanically sound,
some models suggest better performance with a longer basket & radiator,
BUT not how Vortex did it with their mk2, its mechanically weak as piss & heavy as lead even though they used the strongest tube ever used for cb antennas,
mk2 only gives a wide bandwidth,
The performance is a little down on the regular Q.82
close 3rd avanti astroplane on a mast that extends a little over 1/4wave below the hoop & properly isolated at that point,
Im not sure if the Imax needs full 1/4wave radials as the feedpoint is not where the coax connects,
I wish you the best of luck in your new venture
I don't see them as been any different to using a cheap china spectrum analyser as they both work in the same way,
if all you want is to see small changes then a 148gtldx or grant export with the rf gain backed down so your @ about s3-4 will magnify any changes, even a uniden 200 will do the same thing,
proper s-meters unlike radio s-meters won't show significant differences in antennas that are correctly installed at the same tip height
In out tests the IMAX needs isolating from the mast & the radial kit & an effective choke,
it can make a big difference to mast & coax outer braid cmc & improve signal strength,
I seem to recall The DB posting about the capacitor in the middle section bringing all radiating currents on the radiator in phase & raising the end impedance of the radiator,
unlike a regular 5/8 that has 1/8wave of unwanted radiation,
There is nothing like the difference between antennas as the makers claim IF they are all correctly isolated & choked & installed at the same tip height,
The problem is NO maker tells you how to correctly install their antennas,
some do have an edge in our tests
1st Grazioli G-MAX Beats all others but weak in high wind
2nd VECTOR 4000 style antenna adjusted for best signal about .82wave,
There are a few clones out there but imho none are mechanically sound,
some models suggest better performance with a longer basket & radiator,
BUT not how Vortex did it with their mk2, its mechanically weak as piss & heavy as lead even though they used the strongest tube ever used for cb antennas,
mk2 only gives a wide bandwidth,
The performance is a little down on the regular Q.82
close 3rd avanti astroplane on a mast that extends a little over 1/4wave below the hoop & properly isolated at that point,
Im not sure if the Imax needs full 1/4wave radials as the feedpoint is not where the coax connects,
I wish you the best of luck in your new venture
If your trying to measure the low angle lobe you see in models, neither will be of help. In a base antenna at height, 200 yards isn't enough for the lobe to formed yet at, and six miles, even if it is formed, it will be to far above your head (more than a half mile if you have a 5 degree angle of radiation) to measure. And that is before factoring in the curvature of the earth which will only make things worse.
If your trying to measure a change for local contacts, I would use the data from six miles out, even if it is more difficult, its a field measurement that simulates communications with others. 200 yards might work, but I would trust the results from six miles out more. Plus at 200 yards, you would need both antennas at the same height at minimum, if the antenna under test is 30 feet high and the other is at ground level 200 yards away, that won't get you accurate data...
The DB
If your trying to measure a change for local contacts, I would use the data from six miles out, even if it is more difficult, its a field measurement that simulates communications with others. 200 yards might work, but I would trust the results from six miles out more. Plus at 200 yards, you would need both antennas at the same height at minimum, if the antenna under test is 30 feet high and the other is at ground level 200 yards away, that won't get you accurate data...
The DB
thanks ..yes i see a few vortex antennas are silly heavy..has there ever been a side by side test of a V4K and the vortex with the long basket?..i would like to do a test if it has not been done, but i would have to get another V4K as mine has only got the original ring.the bottom of the basket which the tubes are now used at the top of the basket with bigger tubes at the bottom and the 4 middle sections of the radiator which are now at the top ..the original top 3 sections are not used its is also around .82, apart from that all dimensions are original apart from the diameter of the tubing but i don't know if that will affect performance..it has changed bandwidth a fair bit it wider now and the SWR is at its lowest, it was always 1.3 no matter what height it was or what must it was in but now its just below 1.2..but it is on my test mast at the moment which its not been on before but it has been lower at 12 feet and 45 feet on poles and 65 feet on my tower ..the test mast is 35 feet on polesDave, the sdr play units have a supposedly calibrated S-meter in dbm,
I don't see them as been any different to using a cheap china spectrum analyser as they both work in the same way,
if all you want is to see small changes then a 148gtldx or grant export with the rf gain backed down so your @ about s3-4 will magnify any changes, even a uniden 200 will do the same thing,
proper s-meters unlike radio s-meters won't show significant differences in antennas that are correctly installed at the same tip height
In out tests the IMAX needs isolating from the mast & the radial kit & an effective choke,
it can make a big difference to mast & coax outer braid cmc & improve signal strength,
I seem to recall The DB posting about the capacitor in the middle section bringing all radiating currents on the radiator in phase & raising the end impedance of the radiator,
unlike a regular 5/8 that has 1/8wave of unwanted radiation,
There is nothing like the difference between antennas as the makers claim IF they are all correctly isolated & choked & installed at the same tip height,
The problem is NO maker tells you how to correctly install their antennas,
some do have an edge in our tests
1st Grazioli G-MAX Beats all others but weak in high wind
2nd VECTOR 4000 style antenna adjusted for best signal about .82wave,
There are a few clones out there but imho none are mechanically sound,
some models suggest better performance with a longer basket & radiator,
BUT not how Vortex did it with their mk2, its mechanically weak as piss & heavy as lead even though they used the strongest tube ever used for cb antennas,
mk2 only gives a wide bandwidth,
The performance is a little down on the regular Q.82
close 3rd avanti astroplane on a mast that extends a little over 1/4wave below the hoop & properly isolated at that point,
Im not sure if the Imax needs full 1/4wave radials as the feedpoint is not where the coax connects,
I wish you the best of luck in your new venture
Yes Dave tests have been done, on 27mhz and I built scaled versions for 50mhz that I posted about on here,
my results show the vortex dimensions for the longer radials DO give the claimed wide bandwidth but the signal strength is a little bit lower than the original,
The standard vortex has broken /snapped radials more than once at the base because the radiator is too floppy, vortex tube is the strongest tube I ever saw in any antenna but the sections don't fit well, the sections are too long & not enough of them,
Don't get me started on the mk2, how Vortex did it is dumb as a box of rocks,
They left the radiator @ stock length & extended the radials to about 3/8wave,
Tube diameter and proximity to the radiator do effect performance & bandwidth,
as you sweep the radials up towards the radiator the effective electrical length of both get shorter & resonant frequency goes up,
Vortex fatter tubes effect the resonance more than sirio or avanti smaller diameter tube,
That's why I think the .82wave is not really .82wave & why I think that the optimum length astroplane mast is not electrically longer than 1/2wave
while both are physically longer than their effective electrical length,
( ^just my opinion based on looking at models & lots of experimenting )
The Db did some models that suggest there could be something in the extended radials even longer than Vortex used IF you also extend the radiator too,
I have more faith in Db's models than any of the claptrap Vortex published on their website,
Imho the mechanical aspect of such an antenna if you were to do it like Vortex is useless @27mhz
But if you created a radial sleeve using multiple wires to reduce wind load & eliminated the rocking motion snapping the radials off at the base It could be a winning formula ( maybe )
I don't think you need the ring at all,
AVANTI patent claimed the ring allowed the radials to be shorter,
That's BS in my book they tune ok without a ring with almost any length radials & the shorter avanti & original vector are not 1/4wave sleeves electrically,
I am waiting to compare my 50mhz vectors with & without the ring,
imho the no ring version will perform at least as good as the ring version,
it has the added bonus of not having a place for birds to shit from,
You should be able to get vswr almost perfectly flat,
vswr bandwidth will vary depending on diameters & lengths but the gamma should tune most dimensions very low
I have tuned them from 26ft to over 32ft & the sweet spot for a standard length radial setup seems to be around .82wave physical length,
if you want to try the longer radials then you will probably need a shorter gamma strap to bring the gamma rod closer to the radiator,
I had to cut the strap on my long radial version to get it to tune correctly,
getting a good tune is a balancing act of gamma rod diameter spacing & capacitance value and where you set the strap up the radiator,
IF you are using an analyser the gamma capacitor can only tune out the reactance,
the resistive part is adjusted by moving the gamma strap up & down the radiator,
good luck
my results show the vortex dimensions for the longer radials DO give the claimed wide bandwidth but the signal strength is a little bit lower than the original,
The standard vortex has broken /snapped radials more than once at the base because the radiator is too floppy, vortex tube is the strongest tube I ever saw in any antenna but the sections don't fit well, the sections are too long & not enough of them,
Don't get me started on the mk2, how Vortex did it is dumb as a box of rocks,
They left the radiator @ stock length & extended the radials to about 3/8wave,
Tube diameter and proximity to the radiator do effect performance & bandwidth,
as you sweep the radials up towards the radiator the effective electrical length of both get shorter & resonant frequency goes up,
Vortex fatter tubes effect the resonance more than sirio or avanti smaller diameter tube,
That's why I think the .82wave is not really .82wave & why I think that the optimum length astroplane mast is not electrically longer than 1/2wave
while both are physically longer than their effective electrical length,
( ^just my opinion based on looking at models & lots of experimenting )
The Db did some models that suggest there could be something in the extended radials even longer than Vortex used IF you also extend the radiator too,
I have more faith in Db's models than any of the claptrap Vortex published on their website,
Imho the mechanical aspect of such an antenna if you were to do it like Vortex is useless @27mhz
But if you created a radial sleeve using multiple wires to reduce wind load & eliminated the rocking motion snapping the radials off at the base It could be a winning formula ( maybe )
I don't think you need the ring at all,
AVANTI patent claimed the ring allowed the radials to be shorter,
That's BS in my book they tune ok without a ring with almost any length radials & the shorter avanti & original vector are not 1/4wave sleeves electrically,
I am waiting to compare my 50mhz vectors with & without the ring,
imho the no ring version will perform at least as good as the ring version,
it has the added bonus of not having a place for birds to shit from
,You should be able to get vswr almost perfectly flat,
vswr bandwidth will vary depending on diameters & lengths but the gamma should tune most dimensions very low
I have tuned them from 26ft to over 32ft & the sweet spot for a standard length radial setup seems to be around .82wave physical length,
if you want to try the longer radials then you will probably need a shorter gamma strap to bring the gamma rod closer to the radiator,
I had to cut the strap on my long radial version to get it to tune correctly,
getting a good tune is a balancing act of gamma rod diameter spacing & capacitance value and where you set the strap up the radiator,
IF you are using an analyser the gamma capacitor can only tune out the reactance,
the resistive part is adjusted by moving the gamma strap up & down the radiator,
good luck