Too radial or not too radial that is the question.

I’m getting a new base antenna (again)I know if it’s not broken don’t fix it and all that but you know what we’re all like.Anyway the question is can an antenna be SWR’ed with the radials left off.I’m planning on not repeating the tuning carry on like last time and was going to erect a makeshift mast 20 feet up from the ground tune the antenna,Fit the radials that are 2m in length and 4 of them.Then position the thing up in the air Job done.The reasoning behind it was do those radials effect the SWR settings.
Thanks Tom.
26 CT 4029

The matching circuit on the antenna is designed with radials of a certain length being present.  The same antenna with out said radials will have a different "impedance" and by extension higher SWR.  If your lucky, you could try adjusting the matching circuit, but very few have the range of adjustment to account this type of change.  It would be far far easier to find an antenna that isn't designed to need radials rather than remove the radials from an antenna that comes with them.

This is also not getting into other potential issues not having said radials might cause.  There is far more to removing radials than just getting a higher SWR.


The DB

Thanks DB,I did have the feeling it would be important to make any adjustments while they were installed.After last times carry on with the Antenna I’ll erect a makeshift mast 10-15 feet off the ground make the correct SWR adjustments then remove radials as they are 2m in length,get the antenna back up on the roof reassembled and then fixed to swaged poles and bolted to the house.Last time I did it alone and it wasn’t fun nor clever holding on to a T&K bracket with one hand and am antenna with the other.Fresh pants were needed after that mission was accomplished..
Helpers will be used next time around.
Thanks again DB
Tom. 26 CT 4029

As above you can tune it without the radials but it'll possibly have other consequences which may not become immediately obvious such as a change in the gain at different take off angles, especially lower ones.

Also If you tune the antenna on a 20ft mast on the ground then stick it up on the roof of your house if there's a significant change in height the tuning will change due to the change in ground losses. It's resonant point will probably rise a couple of hundred kHz so tune it slightly lower than you want it to be centred on.

Northern Crusader,Now that’s even more valid points I didn’t take into consideration,That’s why we ask I suppose.The difference between temporary mast to tune on the ground and actually fixed position on the house is about 35-40 feet difference,So that idea is blown out the water..loi
I’ve now taken to the idea of getting half scaffolding erected just so tuning and fixing will be 10 times easier and a lot safer.
Health and safety would have crucified me.Thanks for the help and advice as it’s greatly appreciated and has pointed me in the right direction and no cutting corners.
Thanks again Tom.
26 CT 4029

I've just acquired a sirio 2016 and put it up without the radials for the moment and if I'm honest the swr is 1:1 all round and it being a good 30 ft off the ground.
I was led to believe that the radials only effected incoming signals and not transmit ? Can someone correct on on this ? 
Cheers .

To some point yes they will effect both

Morning chazwozza
Yes was told and heard different things about this. It was just a question I wanted to put to the guys on here as the famous Dx commander quoted recently in one of his vids on the net saying radials on the vertical didn't make much of a difference on 11 meter apparently.
Question he needs to ask himself then why do the likes of sirio and other well known antenna makers put them on ? Including himself.
Anyway I will be putting mine on at some point. Anyway question why is it some verticals have them and some don't and if that's the case why don't all verticals have them on as my venom didn't have them .

end fed verticals that need radials, ideally, tend to have current maxima near feedpoint or some current. consider these quarter waves and 58th waves ; half waves do not have much current at feed they have high volts ; where there is high current radials are required quarter wave needs them

11m? 5-8 waves need radials and so do quarters so either you misquote callom or he is wrong
radials do a few jobs help impedance match, reduce ground losses if earth mounted like a shield from a poor ground - the actual earth, reduce common mode on pole or coax...some antennas are more prone to cmc - for ground mount they increase efficiency of antenna

ground mount antenna are the worst of all with a few exceptions

1/2 wave does not normally need much of any radials as current is low

so for quarter and five eights if you dont put radials your antenna will not wrk as well as it could

Thanks for that info i.ll take that onboard . My qth I get so much noise from not only in the immediate surroundings but also power lines in the area which is very annoying and its cost me a small fortune trying to get rid of the noise . The antenna itself works well even without the radials on but I will put them on to see what difference it makes .