An antenna doesn't need radials or a ground to operate unless it's designed to
use them, but they're not indispensable for all designs.

-Robert VA2ERY


the above was taken from a response from Robert on the Miracle whip site..

so my question ..

Would an antenna radiate if we could totally devoid it of a current return path ?

i know people use antennas without earths etc but in the main the coax and /or the rig chassis will add some earthing but what if we could fully remove all possible return path ? That is no chassis coax or actual physical ground /dirt.


billy

intresting post this!! if ya dont need ground planes im taking them of my 20m vert haha

Billy,

It's basic circuit theory that if current is flowing into a node there must be exactly the same current flowing out of it.

If that node is the feedpoint of an end-fed wire, there MUST be an equal and opposite current flowing into something connected to that node - that "something" might be radials, a counterpoise, a ground spike, or the outside of the coax braid. If there really is NO other path, then zero current will flow into the antenna and it will not radiate.

73,
Steve G3TXQ

Billy,

I might elaborate on that a bit:

Imagine a radio in outer space with a Miracle Whip connected directly to the SO239. It has no radials, no counterpoise, no earth spike, and no coax - so will it radiate? Yes it will, because current can flow into the whip, then away from the whip as displacement current, and then back to the feedpoint via the capacitance represented by the bulk of the radio.

If you like, you can think of it as a dipole - one side of the feedpoint is an electrically short whip, and the other side is an even smaller radio chassis. Provided the tuning element can bring the whole system to resonance, there is a circulation path, current can flow, and radiation can take place.

The point I was trying to emphasise in my first post was that there MUST be a return path in some shape or form, even though we might not always recognise it for what it is

Not sure if that helps or hinders!
Steve G3TXQ

cheers steve, yes this is why i asked , even though people state no radials used the chassis is still contributing to the current return path coupled with it say being sat on a car roof and that car may be even sat on the beach ..

the end fedz , again the coax braid is still contributing as well as the chassis..

i think it was a bit of a strange comment from someone who i suspect knows something about antennas. i think he may of got excited about the reports of miracle whip users working dx "without radials" or an earth with the recent high on 10m ..

i think some people get confused with no radials/counterpoise required and the radio/feedline and any coupling to nearby objects doing it instead . but something must be doing it ..


billy

Billy I noticed a VSWR rise the moment I lifted my FT817 and Miracle Whip combination off the roof of my car in Crete, I credited this to the capacitive coupling of the radio chassis to the roof of the car, the antenna was tuned in this configuration and as soon as I lifted the radio away from the roof, the balance of the system was disturbed:

this is my point steve... you still had a return path of sorts.. although you could state you used no counterpoise /earth which i think is where people are getting misled by such statements as no earth required ..

that pic for me just cries out fun radio time ..

congrats on making the contacts you did.. i think the 10m opening has changed peoples views of what the MW can do when conditions are good .. i was beginning to think it was only me that thought these small whip type antennas actually could work

I was banking on the car, and the beach, acting as a return path.

I spent a lot of hours stood there chatting to anyone that came back to my call, sometimes they came one after another, over 30 contacts in 40 minutes, and sometimes it was really hard work 6 contacts in over 3 hours, in all I worked over 400 stations with some amazing DX, 10m was indeed wide open, I did use other frequencies, but 10m was my main band, fun is exactly how I'd describe it, and it has changed my opinion of this little antenna

nice one ,


glad you had fun with it which is what these antennas are for . i love em just for the simple fun factor. took a pic of the set up during summer sat working EU on 40m

I think what VA2ERY meant is that antennas designed to have radials/counterpoise, such as monopoles and end-feds do need to have them or performance will suffer. However antennas such as centre-fed dipoles, and doublets do not need them as the circuit is already complete.

Stewart

fair enough , i may of read it wrong ..

Reading some of VA2ERY's comments on various discussion groups, it's hard not to come to the conclusion that his comment related to his Miracle Whip. He frequently refers to how the antenna works without a counterpoise or ground.

Like I said earlier, that's perfectly possible provided you have a wide-enough range in the matching network to bring the whole system - antenna + return path (whatever it is) - to resonance. Of course the fact that you can match it without an engineered counterpoise/ground system - rather than a "serendipity" return path - may make it convenient, but doesn't necessarily make it an efficient radiator.

Many of the comments I found from VA2ERY related to the Miracle Whip's poor showing in an HFpack "antenna shootout" - it was last in the list apart from a couple of designs which used a 75 Ohm resistor across the feedpoint to achieve a match.

For my own excursions into QRP I've always been able to sling up some sort of temporary dipole or doublet, such as this 40m operation from Malta whilst on holiday:




73,
Steve G3TXQ

http://hfpack.com/antennas/shootoutvertical2002.html

for anyone interested.

Looking at that list, my 500mW input would have been around around 30mW ERP so my 57 report into Virginia, approximately 5,500 miles from where I was in Crete, was pretty damned fine, and the fact he heard me over a European pile up with just 5W input, approximately 200 to 300mW ERP.

I'm in no doubt that the antenna is quite lossy, but with conditions like we've had recently, it's not going to stop you making contacts

That's it steve, i think the biggest hurdle for many is simply realising what to expect . I know a few people who have had them who thought they were going to work the same stations they would on say a doublet with one and then got disheartened. recently has been an exception with especially 10m being wide open .

I had no luck whatsoever on mine till i used a counterpoise . That said i never used it sat on my car roof and was normally sat with it on a bench somewhere or in the back garden on the decking so i probably had very little in the way of an earth except for the radio .. The minute i ran a counterpoise things changed and i started getting heard ..

The ATX is another one i like but the tuning is very much dependant on a counterpoise unlike the MW as in it doesn't seem to tune as a MW would using say the chassis or coupling to a car roof etc ,i found it needs a wire or tape measure or whatever for the ground that can be adjusted in length.

I enjoy these antennas knowing full well what to expect and sometimes 5 decent qso's out in the sticks with minimal gear in the sun is worth 100 sat at home anyday for me ..

i quite fancy trying the MMD ( mixed mode dipole) next ..


billy