On 3/20/2014 2:06 AM, Jon Danniken wrote:
Hi all, I'm cooking up a discone antenna for receiving, and I have a
question about feedline grounding. From everything I have seen, the
discone has an impedance of about 50 ohms, and everyone seems to just
connect the feedline right to the antenna; center conductor to the disc,
and shield to the cone.

My question is about what happens when I ground the shield at the
arrestor block just before the cable comes into the house; without a
balun, won't I just be turning the cone into a ground plane? I know
that there are ground plane antennas, but even though I am new to all of
this I thought that a discone was not a ground plane.

What am I missing here?

Thanks for any suggestions,

Jon

Jon, you are making this much more complicated than it really is.

A discone is a vertically polarized omnidirectional antenna. Just like a
quarter-wave vertical. The difference is that the discone supposedly has
a wide bandwidth.

For receiving purposes, do you care about grounding the shielding to
something if you can receive what you are listening for? Grounding the
shield may cause your receive pattern to change, but that can happen
with nearby trees and nearby structures as well.

Your best bet is to put it up and try it out. You can try grounding and
ungrounding the shield to suit your reception desires, if it even makes
a difference.

Cheers,
John KD5YI

John S wrote:

Jon, you are making this much more complicated than it really is.

A discone is a vertically polarized omnidirectional antenna. Just like a
quarter-wave vertical. The difference is that the discone supposedly has
a wide bandwidth.

For receiving purposes, do you care about grounding the shielding to
something if you can receive what you are listening for? Grounding the
shield may cause your receive pattern to change, but that can happen
with nearby trees and nearby structures as well.

Your best bet is to put it up and try it out. You can try grounding and
ungrounding the shield to suit your reception desires, if it even makes
a difference.

Hi John, my sole reason for grounding the coax at the entry point of the
building is to be code compliant WRT lightning protection.

Jon

On 3/22/2014 12:02 PM, Jon Danniken wrote:
John S wrote:

Jon, you are making this much more complicated than it really is.

A discone is a vertically polarized omnidirectional antenna. Just like a
quarter-wave vertical. The difference is that the discone supposedly has
a wide bandwidth.

For receiving purposes, do you care about grounding the shielding to
something if you can receive what you are listening for? Grounding the
shield may cause your receive pattern to change, but that can happen
with nearby trees and nearby structures as well.

Your best bet is to put it up and try it out. You can try grounding and
ungrounding the shield to suit your reception desires, if it even makes
a difference.

Hi John, my sole reason for grounding the coax at the entry point of the
building is to be code compliant WRT lightning protection.

Jon


I understand that. But, does it prevent you from doing an experiment
while the weather is nice?

If so, then go for it and see if you like it. What are your alternatives?