Skip to main content
10 votes

Does a 1/2 wavelength end-fed antenna need a good RF ground?

An end-fed half-wave operates on a principle that, for lack of a better name, I will call "voodoo". If you look at the standing wave on a half-wave element in isolation, you see that the center is ...
hobbs - KC2G's user avatar
  • 12.5k
7 votes
Accepted

When and why does the size of a ground plane or radials matter?

Perhaps consider that the objective of the ground plane is to present a low impedance. At the feedpoint, the hope is to have all the current go into the antenna, and none of it on the coax common-mode....
Phil Frost - W8II's user avatar
6 votes

How Does the Performance of Elevated Radials Differ from That of Buried Radials?

The number of horizontal radial wires used in an elevated "counterpoise" can be far fewer than the 120 buried wires used by most AM broadcasters, and the even fewer numbers of buried wires often used ...
Richard Fry's user avatar
  • 2,922
6 votes

Why are many ground radials preferable to a single ground stake buried 1m deep?

The purpose of the ground radials isn’t to ground the counterpoise. The purpose of a dense field of radials is to emulate as much as possible a perfect mirror surface, so that, to the far field, the ...
hotpaw2's user avatar
  • 13.5k
5 votes
Accepted

does the shape of an antenna ground plane matter?

We use irregularly-shaped ground planes all the time — car roofs, and metal boxes, and all sorts of things. However, the difference between a ground plane and an antenna with two elements is in the ...
Kevin Reid AG6YO's user avatar
  • 24.7k
5 votes
Accepted

Why are many ground radials preferable to a single ground stake buried 1m deep?

A dipole antenna does not require a connection to an "r-f ground" reference, either in the form of a ground rod or a set of buried radials. Its radiation efficiency typically is ~95% or ...
Richard Fry's user avatar
  • 2,922
5 votes

How thick should counterpoise wires be?

The purpose of the counterpoise is to provide an efficient means of conducting the return RF current of the antenna. In the absence of an efficient counterpoise, the current will return through the ...
Glenn W9IQ's user avatar
  • 18.6k
5 votes
Accepted

How low can a vertical dipole be mounted?

Here is an analysis of a vertical, 1/2 wavelength, 2 meter dipole suspended at various heights above ground: As you can see, as you raise the bottom end of the antenna from near ground level up to ...
Glenn W9IQ's user avatar
  • 18.6k
4 votes
Accepted

Does a 1/2 wavelength end-fed antenna need a good RF ground?

No, it is not needed, but it can improve the antenna system. An EFHW is simply a half-wave length of wire and a matching device, and that's it. Counterpoises are commonly added to shunt common mode ...
Sterling N0SSC's user avatar
4 votes

Does a 1/2 wavelength end-fed antenna need a good RF ground?

The EFHW (end fed half wave) needs to be classified as a specific case of the class of end fed wire antennas. The name is even a bit of a misnomer since the EFHW is often operated on multiple bands ...
Glenn W9IQ's user avatar
  • 18.6k
3 votes

Does RF go through thin corrosion better than DC?

A layer of corrosion between two metals forms a capacitor (or, sometimes, a diode). RF will go through it better than DC, because RF can go through capacitors and DC can't. However, that doesn't mean ...
Kevin Reid AG6YO's user avatar
  • 24.7k
3 votes

Counterpoise wire voltages?

There are a lot of variables involved in calculating the voltage on an antenna. If you require an accurate answer, the solution is to model or empirically measure the particular antenna in question. ...
Phil Frost - W8II's user avatar
3 votes

Does a 1/2 wavelength end-fed antenna need a good RF ground?

There's confusion about counterpoise because there's two kinds of end fed antennas. Both are multi-band, but different approaches to achieve this. The first kind is deliberately non-resonant, uses a ...
James Stanski's user avatar
3 votes
Accepted

How thick should counterpoise wires be?

With only three radials, the wire you use is probably not very relevant. Although a smaller wire has a higher resistance and thus loss, with only three radials directly on the ground your losses will ...
Phil Frost - W8II's user avatar
3 votes

How low can a vertical dipole be mounted?

The voltage is high near the end of any dipole. If you locate the bottom end of a vertical dipole at --and especially below!-- the ground, you are greatly increasing the losses. There is really no ...
Mike Waters's user avatar
  • 8,071
2 votes

When and why does the size of a ground plane or radials matter?

In broadcast AM radio it is standard practice to use quarter-wave towers (because half-wave towers are expensive and more of a maintenance headache). These towers require a ground plane to reflect the ...
SDsolar's user avatar
  • 2,089
2 votes

How thick should counterpoise wires be?

Can you elevate the radials? Two or three properly installed elevated radials can be just as effective as 120 on the ground! By properly installed, I mean that they should be roughly 10 feet high and ...
Mike Waters's user avatar
  • 8,071
2 votes

Counterpoise/ground/radial options for an Inverted L

Here is another answer on this site about buried vs. elevated radials.
Richard Fry's user avatar
  • 2,922
2 votes

Resonant 80m End Fed Halfwave Antenna With Counterpoise - Questions

Originally, I built an 80m EFHW, 130.5 feet long cut for approximately 3.58Mhz. I attached a 49:1 UnUn at the feed point 13 feet above the ground with coax back to the shack. I did not use a ...
Raonoke's user avatar
  • 151
2 votes

does the shape of an antenna ground plane matter?

It depends entirely on what you are testing. If you just want to see if it works, there is a minimum size to the ground plane. What you are describing sounds way too small, but that depends on the ...
user10489's user avatar
  • 6,485
2 votes

Vertical Hustler - do I need any radials?

The Hustler web site says: "For optimal performance, radial wires should be used." Somewhere else, there is a recommendation for sets of 3 tuned radials per band on which you plan to operate. A ...
hotpaw2's user avatar
  • 13.5k
2 votes

Why are many ground radials preferable to a single ground stake buried 1m deep?

Because the radials act as ground, and they're better at it than actual ground. Ground (as in: dirt) isn't a great conductor. A couple laid out good conductors hence work much better as ground plane ...
Marcus Müller's user avatar
2 votes

Why are many ground radials preferable to a single ground stake buried 1m deep?

Surely a 1m copper stake provides better ground connectivity for a vertical dipole? What really matters is conductivity. Current doesn't just go in the ground rod and then it's done. It has to flow ...
Phil Frost - W8II's user avatar
1 vote

End fed long wire antenna causing issues

I'm no expert on EFHWs but here's what i've learnt with mine (happy to be corrected if i've got anything wrong by the experts of the forum). Fundamentally, an EFHW (with no counterpoise, or connected ...
t252's user avatar
  • 697
1 vote

End fed long wire antenna causing issues

The higher receive noise is possibly an indication that RFI from your house and/or computer is getting up to the feed point of your off-center fed dipole (what you are calling an "end fed") ...
hotpaw2's user avatar
  • 13.5k
1 vote

How Do Ground-Mounted Verticals Compare to Elevated Verticals?

Below is a graphic comparing some of the operational parameters of ground-mounted and elevated vertical radiators for the 40-meter band. Their performance when installed at sites with relatively poor ...
Richard Fry's user avatar
  • 2,922
1 vote

Vertical antenna

As a start, below is a NEC analysis of the system described in the OP. The horizontal radials lie along the +Y or the + and -Y axes.
Richard Fry's user avatar
  • 2,922
1 vote
Accepted

Counterpoise/ground/radial options for an Inverted L

Either elevated radials, or radials lying on the ground or buried just below the surface can work just fine. The difference usually comes down to what's more convenient to install. I would not ...
Phil Frost - W8II's user avatar
1 vote

When and why does the size of a ground plane or radials matter?

This is commonly described as the ground plane acting as a reflector, so that there is effectively a second quarter-wave element “below the ground plane”. It IS commonly described that way, but it is ...
Mike Waters's user avatar
  • 8,071
1 vote

When and why does the size of a ground plane or radials matter?

The length and number of buried radials desirable for a given vertical monopole depend significantly on the operating frequency and the conductivity of the earth in which they are buried. The graphic ...
Richard Fry's user avatar
  • 2,922

Only top scored, non community-wiki answers of a minimum length are eligible