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7 votes
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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
7 votes
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Radials on a vertical, spread out evenly or not?

The purpose of the radials is to increase the effective ground conductivity, thus reducing losses. As you propose to have 16 radials but in four groups, I'd expect the efficiency to be somewhere ...
Phil Frost - W8II's user avatar
7 votes
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HF Vertical antenna with no radial and loading coil but only ATU for 80m to 10m in a boat

On boats the traditional solution is to use the backstay as the radiator, with an insulator near the top, another near the bottom, and an insulated wire running to the tuner. The water serves as the ...
tomnexus's user avatar
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6 votes
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Vertical Antennas

First: do you know about pskreporter? You're definitely getting heard, including one spot on 40m from New Zealand. Sometimes FT8 takes some patience, and it seems like no one wants to come back to you ...
hobbs - KC2G's user avatar
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6 votes

Radial length for vertical antennas?

Rule of thumb: if the radials are elevated, at least two resonant radials for each band. If the radials are buried or lying on the surface, at least 16 radials, each at least a 1/4 wavelength at the ...
Phil Frost - W8II's user avatar
5 votes
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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
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5 votes

Are Elevated Radials Necessary for Elevated, 5/8-wave "Ground-Plane" Antennas?

Elevated radials are required in order to increase/optimise the radiation possible from any such elevated "GP" monopole or whip antenna. If the elevated radials are symmetrically arranged and lie in ...
Richard Fry's user avatar
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5 votes

Ground radials: Electrical difference between 14 gauge and 18 gauge? Lifespan difference?

Larger wire will have less resistance. However, the resistance of the radials in either case is negligible compared to the soil resistance, so I wouldn't worry about it. Longevity would be my concern....
Phil Frost - W8II's user avatar
5 votes

Using two short mobile HF antennas to make a vertical dipole

To begin the discussion, it is helpful to understand the effects of shortening any antenna to a length below resonance. In all cases, the directivity of the antenna is reduced but this tends to be a ...
Glenn W9IQ's user avatar
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5 votes

What do radials really do for a vertical antenna?

Both #1 and #2 are the same. Accelerating currents are what sum up to create an EM field. And the law of conservation of charge requires that the currents be balanced. If you have a quarter wave ...
hotpaw2's user avatar
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5 votes
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Using threaded rod for VHF radials

I was about to say it would have no impact - In my experience thread has no effect. I've used threaded rod all over antennas though not usually for the whole element. But scratching a bit found this ...
tomnexus's user avatar
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4 votes

Radials on a vertical, spread out evenly or not?

The effects of using unequal length buried radials on the radiation patterns of a monopole are not very significant, as shown by the NEC4.2 analysis below.
Richard Fry's user avatar
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4 votes
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How to calculate phase constant for a coaxial cable?

The velocity of propagation for the TEM mode $V_p = \frac{c}{\sqrt{\epsilon_r}}$, i.e. in your case about $0.626\,c$, or $1.877 \times 10^8\,\frac{\mathrm{m}}{\mathrm{s}}$. (This is a bit different ...
hobbs - KC2G's user avatar
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3 votes
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Hobby Wire for Ground Radials

Sure it will work. Metal wire is metal wire. The electrons don't care about the packaging. 24 gauge wire is thin enough you might be concerned about the resistance of the wires, which will decrease ...
Phil Frost - W8II's user avatar
3 votes

What is the effect of using different number of radials with ground plane antenna

Below are NEC4.2 analyses showing the intrinsic, free space radiation patterns of (1) a ground plane antenna having two pairs of co-linear, λ/4, horizontal radials spaced at ±90°, and (2) a comparison ...
Richard Fry's user avatar
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3 votes

Dielectric Constant of Insulation/RF Permeability

Developing this comment of W2ASC (above): But, given the fact that radials are effective even when buried in a few inches of soil, my assumption was (and still is) that whatever difference exists ...
Richard Fry's user avatar
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3 votes

Do the Horizontal Conductors of a Ground Plane Antenna Adequately Decouple Its Feedline?

Below is a NEC4.2 comparison of the v-plane patterns of a 1/4-wave ground plane antenna mounted 5m above level Earth and using 4 x 1/4-wave, horizontal radials, with / without a coax transmission line ...
Richard Fry's user avatar
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3 votes

What Are Some of the Most Important Characteristics Applying to the Radiation of Monopole Antenna Systems?

VERTICAL MONOPOLE, EARTH, and BURIED RADIALS as FACTORS in ANTENNA SYSTEM RADIATION EFFICIENCY Considerations: The components shown in the ...
Richard Fry's user avatar
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3 votes

Which is Better to Use with Vertical Monopoles: Buried Radials or Ground Screens?

The information below is extracted from the "benchmark" 1937 I.R.E. paper* of Brown, Lewis & Epstein of RCA Laboratories, and is based on their accurately measured data for these systems. IMO, ...
Richard Fry's user avatar
  • 2,922
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
3 votes

Using two short mobile HF antennas to make a vertical dipole

People can and do use a pair of mobile antennas to make shortened dipoles. A "hamstick dipole" is one example. One application for such an antenna is in a mobile station which for whatever reason ...
Phil Frost - W8II's user avatar
3 votes

Radials on a vertical, spread out evenly or not?

As long as the radials are symetrical it will make no noticable difference. A single radial opposite the other half of a dipole or 2 radials opposite each other will yield a reasonable pattern. The ...
Keith Martineau's user avatar
3 votes

What do radials really do for a vertical antenna?

Radials do both, but reflect is the wrong word and the reasoning behind increasing conductivity misses the point. A monopole vertical antenna is really still a dipole, except that the vertical portion ...
user10489's user avatar
  • 6,485
3 votes

radials for 6 band Hustler vertical

20-foot (6.1 m) radials are certainly better than nothing; your Hustler would work with 20' radials, just not as well as it would with longer radials. 20 feet is longer than a quarter-wavelength for ...
rclocher3's user avatar
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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

What do you connect antenna Radials to?

Radials are grounded to the feedpoint. For instance, the shield of the coax feeding the quarter-wave antenna. For AM radio broadcasting stations, there are radials every 3 degrees (120 of them) ...
SDsolar's user avatar
  • 2,089
2 votes
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What do you connect antenna Radials to?

The radials are not connected to the earth. Here's a photo of a ground plane antenna. They are connected together as shown to the coax shield. This shield should be connected to the common on the ...
Mike Waters's user avatar
  • 8,071
2 votes

Do Buried Radials for Vertical Monopoles Need to be No Longer than the Monopole Itself?

Below is a NEC4.2 study comparing the fields radiated by an eighth-wave, series-fed vertical monopole driven against sets of thirty buried radials of 1/4 and 1/8 wavelength (other things equal). The ...
Richard Fry's user avatar
  • 2,922
2 votes

Is The Lowest Antenna Terminal Feedpoint SWR Always Optimal?

Below is a table showing that this is not always the result, for every antenna configuration. In this case, the configuration with the lowest system SWR(50) also has the lowest system radiation ...
Richard Fry's user avatar
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2 votes
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RFI from radials

You might look into a noise cancelling device. The principle of operation on this is to use a second antenna to 1) capture the same noise but phase shifted 180º and 2) mix/add to the primary antenna's ...
webmarc's user avatar
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