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See also: the virtual ground node generator for balanced transmission lines


in-line "V.G.N.G.", for short

also known as the

Errante's Holyground
the network that works miracles!

Errante's in-line Virtual Ground Node Generator - VGNG

Errante's in-line virtual ground node generator.

Freq. range: 1 to 30 MHz
Input imp.: 50 Ohm
Output imp.: 50 Ohm
Input/output SWR: 1:1 within range
Insertion loss: -0.01 dB
RF power: 3 KW cw
Sockets type: SO-239
Weight : 1 Kg ca.


ERRANTE's in-line VIRTUAL GROUND NODE GENERATOR : what it is, how it works and what it does.


by Francesco Errante

The Errante's in-line virtual ground node generator is a radioelectric circuitry based on the same principals and schematics of his own original patented virtual ground monopole HF antenna design.
The reader who's not already familiar with the virtual ground node mechanism is strongly adviced to read about the "virtual ground monopole HF antenna and its background prior to proceeding to the reading of this page.

The in-line VIRTUAL GROUND NODE GENERATOR (in-line V.G.N.G. for short) is a symmetric radioelectric network which converts an unbalanced RF signal into two precisely identical signals and re-converts them back into a non-inverted single unbalanced RF signal. While doing this, a virtual ground node is generated at its center. It can be effectively described as being an "Un-Bal-Bal-Un" network.
In practice the device, as presented in here, has both the input and output gates terminated onto a 50 Ohm impedance value and SO-239 type of connectors to match the most common co-axial line impedance standard and it is optimized for HF operations between 1 and 30 MHz. Within its specified range, this device appears to be "transparent" between the RF source and the load [SWR = 1:1] and exhibits an extremely low insertion loss [-0.01 dB] However, it can be made to suit any other input/output impedance values and frequencies spectrum.

The in-line V.G.N.G. can generate a virtual ground node at any point of a co-axial line in un-balanced transmission line system. This is, infact, its function. This device is also available in a version for balanced lines.

Main applications:

1) It can be employed to stabilize a whole RTX un-balanced system, however complex it could be, by providing a reliable and centralized RF earth grounding system. As most people may have already experienced, RF earth grounding is a very difficult task and has nothing to do with the conventional safety earth grounding solutions;
N.B. For safety reasons, where required, all the equipment must also be earthed the conventional way and the chassis of the in-line VGNG can also be wired to the building safety earth grounding circuit. All the system equipment chassis should be wired to the provided earth bolts on the in-line VGNG chassis by the shortest route.

2) It can be employed to provide a reliable way to short-circuiting antennas who have not antistatic protection, without the need for modifications or even reaching them up on the roof. Since the in-line VGNG exhibits a solid short circuit to the DC current on both its gates, all the electrostatic charges collected by the aerial and/or the co-axial outer conductor will be discharged via common ground and into the building safety earth grounding circuit;

3) It can be used to stabilize RF co-axial lines exposed to third party hertzian radiation;

4) It can be employed to stabilize reactive loads at their feeding points.

Scientific relevance:

The in-line VGNG enables physics and RF laboratories to have a reliable RF earth grounding systems as a precise reference for test and measurement.

Operational advantages:

a. the in-line VGNG is easy and fast to deploy;

b. in-line VGNG helps to improve E.M.I. compatibility within high equipment density environment.



Question: I run a virtual ground HF antenna, do I still need an in-line VGNG ?
ANSWER: NO ! Your virtual ground antenna system already provides all the R.F. earth grounding you need. However, while using a different aerial an in-line VGNG might be needed.

Question: Where should I place it along my transmission line?
ANSWER: Where the un-balanced RTX system comprises only of a TX/RTX-SWRmeter-coaxial-antenna, the in-line VGNG must be placed right onto the TX/RTX antenna socket.
N.B. If an antenna tuner is used, the in-line VGNG must always be placed before it, right on its input socket.
If a linear power amplifier is used the in-line VGNG must be placed on its output gate.
Where the system comprises of TX/RTX, a linear power amplifier and an antenna tuner, the in-line VGNG must be placed between the amplifier and the antenna tuner.
If a filter, such as an anti TVI, is used place the filter between the amplifier and the in-line VGNG. Moreover, the filtering should improve and the system will also benefit by the added VGNG's out-of-band own signal rejection.
N.B. The in-line VGNG should be inserted in the transmission line by using a short but comfortable RG-213, or better, patch lead. Wherever possible use double male connectors to plug the in-line VGNG in.

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All the concepts, methods, designs and devices presented on this web site
are the original novelty works of FRANCESCO ERRANTE.
Patents & Copyright © 1985- of FRANCESCO ERRANTE.

Material is governed by the Copyright, Designs and Patent Act.
No reproduction, in whole or in part, without written permission.
Copies of these documents made by electronic or mechanical means, including information storage and retrieval systems, may only be employed for personal use.
All rights reserved.

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All rights reserved. Copyright © 1985- Francesco Errante
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