Discussion in 'Antennas, Feedlines, Towers & Rotors' started by AE7F, Jun 18, 2015.
Actually it is more like 38 feet or so for a 20 meter 5/8 wave antenna....
HF2V is a full quarterwave on 40mt, 38% efficiency (on a good ground plane , I don't know your) seems a little bit low .....
If you achieve 58,5 ohm reading @antenna feedpoint, something is lossy , and Yes, RRad/Rloss can kill your efficiency .
I read 40 ohm with MFJ259B (let's take reading as-is) on my HF(9)V over 30 elevated radials , HF2V should be even better.
Also, on 80mt you have a 50Khz 2:1 window and 40 ohm reading , still too high for a 1/8 lambda radiator, your efficiency can be raised, I repeat, 2V is fantastic to play with on 80 also.
AFriend of mine has the 43 ft one could never hear much and not able to make many contacts till
one day he looked inside at the base and found the center connection inside was never connected or
soldered now hw knows what blew his ts440 finals of course all zero five said was sorry send it back and
we will fix the antenna .. too bad for your radio but something else must have blown the finals!
I will never buy one!
Thank you Federico. I appreciate your posts.
My ground plane consists of materials that I had - steel mesh and if I recall correctly, only about 8 copper radials of about 11 meters in length. The radials are bonded to the steel mesh and all of this is bonded to a copper ground rod.
I think I might be better off just adding more copper radial wires on the ground as I'm not sure what the elements have done to the steel mesh.....
Also, I got the 160m kit working so here are the new plots:
One can see that 80m bandwidth was affected but 40m still looks great.
I really want to do some experimenting to see if adding 160m is worth it. It might be and it might not but it is nice to have 3 bands on a small footprint vertical. If I could add 30m to it, I could remove the 30m dipole off of my spiderbeam, although it's nice to have an RX antenna to compliment the vertical. I know there is a 30m kit as well but I'm sure the compromises really start to add up.
Also, with all of the coils on this antenna, it would be nice to be able to quantify their added losses for consideration as well.
Eventually, I will move this antenna and experiment with elevated radials and probably even a metal fence ground but I want to get a good feel for it first.
That stinks. I had a TS-430 and it was a really good radio.
I'm considering all kinds of things now in regards to the ZF. The easiest thing to do first would be to just remove the transformer and the topmost 10ft of aluminum from the antenna and use it as an extremely rugged 40m 1/4 wave. It would be very nice for that. However, as it is very durable and easy to work with, install, take down, etc., maybe I will do some modifications to it to really make it a more specific antenna. I like the work of Phil Salas regarding this antenna:
My math says the length to get the optimum low angle radiation from a 20M (14.00 MHz) unbroken conductor (no phasing devices) vertical is 43.15 ft.
That's .65 waves tall. It's just nemed a 5/8 wave for convienience.
Close to double that is how long I made my EDZ antenna.
Am I in Error ???
Not that simple because the match required for it reduces the physical length some. BTW 5/8 wave is .625 not .65. Also why would you tune it for 14.00?. 14.175 would be middle of band and a 5/8 wave physical length there would be about 41 feet 3 inches vs about 41 feet 8 inches for 14.000. In either case though it would be shorter with match which is part of electrical length.
????? I'm not sure where you are getting that from, but that's not how matching works.
A matching network doesn't lengthen or shorten anything.
We simply obtain the impedance of the antenna, and calculate out a matching network based on that impedance. It matters not whether it is 0.65 or 0.625 wavelength - we can design a matching network for either.
You are trying to suggest that match is invisible in electrical effective wave length of antenna. Such is not they case.
I'm not suggesting anything.
I'm saying that you have a basic misunderstanding of the design and function of matching networks, and how they are used to match the antenna's impedance to the transmission line.
IOW, this is wrong:
Again, a matching network doesn't lengthen or shorten anything.
We simply obtain the impedance of the antenna, and calculate out a matching network based on that impedance.
You're prob thinking of an series inductor that very roughly matches an antenna somewhat physically shorter than a 1/4 wavelength.
The part that you're missing is that we use a capacitor that very roughly matches an antenna that is somewhat physically longer than a 1/4 wavelength. In that sense, one could say (crudely and somewhat inaccurately) that the capacitor "shortens" the antenna.
Of course an inductor doesn't physically lengthen anything, just as a capacitor, or any other matching network, doesn't physically shorten anything.
The matching network is simply chosen to match whatever impedance we find at the antenna terminals, whatever the antenna's physical length might be.