The antenna only has 3 radials, how much difference does that make?An 1/4 wave GP will have higher lobes as an 5/8 wave antena.
An 5/8 antenna its self does not add power it just sends rf in a lower lobe or bundles it better as an 1/4 wave which "can" be a benefit.
Sometimes an 1/4 wave GP just can have the edge over an 5/8 antenna depending on the higher lobes working better at that moment for you.
If in doubt put up the GP isolated, and fit an 1:1 choke directly under the plug at the coax, so that nothing can interfere with the radiation pattern, and just the antenna does the work.
My bet is that you won't notice muchy difference, we are talking 1 dB changes here where we can just make out 3 dB differences in signals.
My Imax 2000 is mounted on a 7 feet alu pole on the roof ( non resonant length) has 17 feet radial wires because it is used from 10 back to 17 meters on 5 bands, (10/11/12/15/17 meter)
With isolation and without no differences were noted, the 4 radial wires were enough.( clamp on ferrite at the connector type 31 material)
My Diamond X 510 N is mounted on polyester pole ( 2 meter and 70 cm) has 3 radials for it and clamp on ferrites around the coax, no difference with or without the clamps, meaning the coax is "clean" from RF.
Since the mast is polyester it will play no role.
Back to the original poster Q:
Put it up and see how it works, if it is an GP with 4 full size radials it will work well.
There are no miracle antenna's and you can go the short way set it up and don't worry, or put it up isolated from the mast and use a 1:1 choke at the feedpoint on the coax to isolate the whole antenna.
Problem will be that any metal within 1/2 wavelenth off the antenna will have some influence on the radiation pattern through coupling.
When i transmit on my 160 meter vertical i can measure the rf on my OCF even if that is horizontal and well away from the vertical,
Even isolated your mast will still have an influence or you should use an polyester mast, and still have to choke the coax.
Life isn't all that simple, theory and practice...
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Ground plane vs metal mast
- Thread starter Confused
- Start date
Confused,
everybody has their own idea of what is a proper installation,
after fixing peoples problematic installs using info from w8ji the guys that model on here & g3txq's choke charts,
i take the view that its better to try and minimise unwanted current & noise than leave it to luck,
locals don't ask me whats up unless they have rfi or noise or both so its no surprise their antennas perform better when their mast & coax & everything connected to it are not part of the antenna radiating & picking up noise,
i have a 31mix ferrite choke near the radio, a 5 turn on 4.25" choke at the antenna,
i made a homebrew w2du choke from about 40 61mix beads on rg393 for experimenting.
everybody has their own idea of what is a proper installation,
after fixing peoples problematic installs using info from w8ji the guys that model on here & g3txq's choke charts,
i take the view that its better to try and minimise unwanted current & noise than leave it to luck,
locals don't ask me whats up unless they have rfi or noise or both so its no surprise their antennas perform better when their mast & coax & everything connected to it are not part of the antenna radiating & picking up noise,
i have a 31mix ferrite choke near the radio, a 5 turn on 4.25" choke at the antenna,
i made a homebrew w2du choke from about 40 61mix beads on rg393 for experimenting.
as said a choke directly under the antenna connector, and ground your station.
My Imax 2000 is used for more bands, hence the choke is somewhat more directed to the lowest frequency used 17 meter.
The last coax here from the antenna switch 3 foot length has full mix 31 clamp on ferrites, every cable to the radio has the same (power supply cable, microphone cable USB cable for digital modes even the speaker cable)
The station is grounded with a 6 feet very thick wire to the special made ground rod 12 feet deep in rich sea clay here outside the window and 2 more rods 6 feet away.
There is 3000 feet radials in/on the ground for the vertical for 160 - 40, and additional 15 ground rods 10 feet deep all connected to the radial field and house ground.
Bit overdone i admit, but it partly is the reason i have so low noise here on the edge of the city.
I worked 5 Japanese stations from the Netherlands on 160 running 20 watts digital mode from the FT991A.
My Imax 2000 is used for more bands, hence the choke is somewhat more directed to the lowest frequency used 17 meter.
The last coax here from the antenna switch 3 foot length has full mix 31 clamp on ferrites, every cable to the radio has the same (power supply cable, microphone cable USB cable for digital modes even the speaker cable)
The station is grounded with a 6 feet very thick wire to the special made ground rod 12 feet deep in rich sea clay here outside the window and 2 more rods 6 feet away.
There is 3000 feet radials in/on the ground for the vertical for 160 - 40, and additional 15 ground rods 10 feet deep all connected to the radial field and house ground.
Bit overdone i admit, but it partly is the reason i have so low noise here on the edge of the city.
I worked 5 Japanese stations from the Netherlands on 160 running 20 watts digital mode from the FT991A.
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Wow ! I'm doing a lot of apologizing on this thread ! Where are my Manners ? I forgot & my apologies , Welcome to the forum Confused " Stay Healthy & Safe ! 73 & God Bless ! Leo
Where are my Manners ? I forgot & my apologies , Welcome to the forum Confused " Stay Healthy & Safe ! 73 & God Bless ! Leo
Grounding your antenna by bringing up a wire more as 1/4 wavelength does nothing for getting RF off the antenna ground connection, it can even work to add noise.
You should always keep the ground rod wire to the radio shorter as a 1/4 wave on the highest frequency you will work on, otherwise that ground wire will add noise and work as antenna, or form a high impdance path nullifying the earth connection for noise.
Secondly, out of safety, ALWAYS connect your separate radio ground to the electricity ground, so both are at the same potential.
In case of a lightning hit and separate grounds there will be different voltages and currents in both systems causing massive damage.
All my coax cables are grounded just before entering the house on the same rod the radio gear is grounded and the house ground is also connected to there 3 ground rods 10 feet deep.
I should have the lowest earth resistance for miles around with 18 ground rods in my system and 3000 feet radials, as was proven by a check for safety of my house electricity system, the guy never saw such low resistance to earth..
Having a choke with the antenna and a good ground below at the entrance of the house keeps the coax free of RF, add chokes below on the coax to the radio and you did all you could do.
The rest is atmospheric noise, propagated noise from city's and other larger noise sources, neighbours etc.
I spend months here finding all sources of noise from cheap chargers and LED lights, and replaced them with my neighbours.
3 or 4 radials won't matter much the change in signal will be 0.1 dB max.
An dipole has to do with one and still works
The more the better but at a certain point you have deminished returns for all the extra work.
Put it up, use it and have fun.
If you want more knowledge about antennas there is enough on the net or in old fashioned books like I have. ( RSGB, ARRL, Low band dxing etc etc.)
And experiment, you learn the most from that.
You should always keep the ground rod wire to the radio shorter as a 1/4 wave on the highest frequency you will work on, otherwise that ground wire will add noise and work as antenna, or form a high impdance path nullifying the earth connection for noise.
Secondly, out of safety, ALWAYS connect your separate radio ground to the electricity ground, so both are at the same potential.
In case of a lightning hit and separate grounds there will be different voltages and currents in both systems causing massive damage.
All my coax cables are grounded just before entering the house on the same rod the radio gear is grounded and the house ground is also connected to there 3 ground rods 10 feet deep.
I should have the lowest earth resistance for miles around with 18 ground rods in my system and 3000 feet radials, as was proven by a check for safety of my house electricity system, the guy never saw such low resistance to earth..
Having a choke with the antenna and a good ground below at the entrance of the house keeps the coax free of RF, add chokes below on the coax to the radio and you did all you could do.
The rest is atmospheric noise, propagated noise from city's and other larger noise sources, neighbours etc.
I spend months here finding all sources of noise from cheap chargers and LED lights, and replaced them with my neighbours.
3 or 4 radials won't matter much the change in signal will be 0.1 dB max.
An dipole has to do with one and still works
The more the better but at a certain point you have deminished returns for all the extra work.
Put it up, use it and have fun.
If you want more knowledge about antennas there is enough on the net or in old fashioned books like I have. ( RSGB, ARRL, Low band dxing etc etc.)
And experiment, you learn the most from that.
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Grounding your antenna by bringing up a wire more as 1/4 wavelength does nothing for getting RF off the antenna ground connection, it can even work to add noise.
You should always keep the ground rod wire to the radio shorter as a 1/4 wave on the highest frequency you will work on, otherwise that ground wire will add noise and work as antenna, or form a high impdance path nullifying the earth connection for noise.
Secondly, out of safety, ALWAYS connect your separate radio ground to the electricity ground, so both are at the same potential.
In case of a lightning hit and separate grounds there will de different voltages and currents in both systems causing massive damage.
All my coax cables are grounded just before entering the house on the same rod the radio gear is grounded and the house ground is also connected to there 3 ground rods 10 feet deep.
I should have the lowest eart resistance for miles around with 18 ground rods in my system and 3000 feet radials, as was proven by a check for safety of my house electricity system, the guy never saw such low resistance to earth..
Having a choke with the antenna and a good ground below at the entrance of the house keeps the coax free of RF, add chokes below on the coax to the radio and you did all you could do.
The rest is atmospheric noise, propagated noise from city's and other larger noise sources, neighbours etc.
I spend months here finding all sources of noise from cheap chargers and LED lights, and replaced them with my neighbours.
3 or 4 radials won't matter much the change in signal will be 0.1 dB max.
An dipole has to do with one and still works
The more the better but at a certain point you have deminished returns for all the extra work.
Put it up, use it and have fun.
If you want more knowledge about antennas there is enough on the net or in old fashioned books like I have. ( RSGB, ARRL, Low band dxing etc etc.)
And experiment, you learn the most from that.
So you're saying that a ground wire from the antenna to the ground rod should be no more than a 1/4 wavelength or it could add noise? The feedpoint would have to be no more than 8 or 9 feet above ground. Are you saying to not ground the antenna if it's mounted higher than that? Can you ground the radio by running a wire from the chassis to the screw on the wall outlet? I heard somewhere that the screw is connected to the house ground. I've spent a lot of time researching on the internet and taking notes but it's been almost impossible to find definite answers. People smarter than me disagree on what's what. Is there a good antennas for dummies book?
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Confused,
After reading two pages of replies to your initial post, I now share your user name.
I suggest mounting your 1/4 wave ground plane (a great antenna even with three radials) on any length of mast, isolate it using electrical tape, and enjoy.
Also, if you’ve been hanging around for a couple of years, you likely have a good feel for who the really knowledgeable members are (they can be counted on one hand). I’ve found the best avenue is to ask one or two of them for help via private message. Saves time and a lot of frustration.
Good luck!
Jim
After reading two pages of replies to your initial post, I now share your user name.
I suggest mounting your 1/4 wave ground plane (a great antenna even with three radials) on any length of mast, isolate it using electrical tape, and enjoy.
Also, if you’ve been hanging around for a couple of years, you likely have a good feel for who the really knowledgeable members are (they can be counted on one hand). I’ve found the best avenue is to ask one or two of them for help via private message. Saves time and a lot of frustration.
Good luck!
Jim
http://www.arrl.org/grounding
Have a read up
Have a read up
Well there are a lot more than a handful of knowledgeable members on here, take that to the bank. 73'sConfused,
After reading two pages of replies to your initial post, I now share your user name.
I suggest mounting your 1/4 wave ground plane (a great antenna even with three radials) on any length of mast, isolate it using electrical tape, and enjoy.
Also, if you’ve been hanging around for a couple of years, you likely have a good feel for who the really knowledgeable members are (they can be counted on one hand). I’ve found the best avenue is to ask one or two of them for help via private message. Saves time and a lot of frustration.
Good luck!
Jim
Ocean One Cape Hatteras
I must admit , Jim got me on that One ! Iv'e been into 11m & Electronic over 50 years , since I joined this forum , I learn something new almost daily . This is just my thoughts , Don't over Think Things , Hook it Up & Enjoy the Hobby . My A-99 is mounted on a Galvanized steel Push Pole , 48' to the tip , 2 ground rods @ the base & I don't even know how long the ground wire is . I have World Wide barefoot , but do have an amp . I started off w/ a RS under $20 GP antenna , that thing worked awesome & I was only about 15-20' to the tip @ the time . Just stick around on here like I did over 6 years ago . Most here have seen a lot of " Hit & Miss " members . You'll be glad you took my advice ! We have a whole lot of knowledge here & you started to crack the shell . Swr(s) are fine you have some kind of ground .... Sit Back & Yack on the radio . ( jmo ) Stay Healthy & Safe ! 73 & God Bless ! Leo
I agree, ENC.
Lots of knowledgeable members here.
But only a handful of really knowledgeable ones.
73
The RF ground plane is not grounded to the earth, the whole point of a RF ground is so the RF doesn't use the earth. The reason for that is that RF current flows better in radials/counterpoise which are a better conductor than the lossy earth and the more current that flows in the RF ground, the more flows in the antenna and the stronger signals you have.
You therefore need to have a separate ground for lightning which is where your ground rods come into play.
With radio you have three grounds, each does a separate job.
1) RF ground explained above.
2) Lightning ground - self explanatory.
3) Electrical ground so you don't get electrocuted by your radio gear.
- No one is chatting at the moment.