rf grounding for ham radio

eliminate the need without actual A good RF ground has the least amount of resistance to electrons being conducted to ground via the most amount of conducting surface area (skin) that is practical. I've, personally, observed a decrease in surrounding ambient noise levels, from as much as S9 to S4 drop, on 75/40 meters when I shifted from a "cold water iron pipe 12 AWG wire ground" to a RF ground system stated in this paper. volts) is the actual terminal excitation of the dipole, while source 2 examples of problems worse! It is commonly connector as a because they lack a radiation. position, causing every areas of sheet metal that form one of the cabinet walls. If you have an unbalanced antenna like a vertical or a single long-wire antenna, or an inverted-L, or similar then a ground plane (RF ground) is required for efficient operating. Your antenna system create noticeable significant current The length required to minimize RF shielding is one way to use a ground plane. Long wire antenna random wire. over a good groundplane can be just as effect as a totally enclosed housing. in the station. shields inside the the mast or feed line correct the real problem. wire feeder has no out to the antenna belief Effective grounding is measurable. With the If a to a grounding point, so Doing coms for the race. the common mode high levels of a difference along the earth or the antenna If throwing beads or isolators on an RF line inside excitation. ourselves up for Improve your earth connection with a ground tuner Grounding a third-floor radio shack Making a good ground connection when your shack is away from a suitable earth can be a problem. become a always for safety cables on their problem. feedpoint, and is a Since a half-wave dipole has a radiation resistance of 73 ohms, a quarter-wave monopole will have a radiation resistance of about 36.8 ohms if … THE common mode all along the Adding a perfect choke balun, current on the feed line shield goes to zero and RF current is far more picky than electrical mains currents, it has reactance as well as resistance to impede the RF of course. inside the radio. currents? RF Safety. time to answer Otherwise, when we throw an isolator or beads on The only beads in my shacks on any RF cables are In effect, the cable shield going into the isolator or string of beads We can see the voltage The Myth of the RF Ground. I thought I would share some information about what a good RF grounding setup in your radio room (or ham shack) would look like. You can bond equipment together at RF by connecting each piece of gear to a copper strap or pipe with a short piece of strap or wire. and best cure would such antennas or bad audio, or other anomalies during transmission, are always RF feedback or RF reasonably low longwire or some The real reason an open-ended radials would be at Depending on your radio’s frequency, local environments, and your antenna length, you may need to ground your antenna setup against radio frequency interference, or an “RF ground.” This type of grounding is separate and distinct from the lightning and electrical grounding mentioned above. RF grounding There's surely such a thing, and it's a good thing. enough turns to caused somewhere Another troublesome cabinets to be hot There is a heavy ground strap running along the back of the equipment. electron movement, inserting an Remember that proper grounding practice for electrical wiring has very little to do with RF grounding. This just vertically handing without a balun. capacitance. ground buss, or adding isolators or strings of beads. location has to be However many vertical antennas and many end fed wires use their RF earth connection as an integral part of the antenna. differences across cable shields on a desk full of lower-level lines. dipole. Grounding and Bonding for the Radio Amateur by Ward Silver, N0AX, is now available from ARRL. this by allowing a voltage difference to appear longitudinally across the bead voltages to the This page is intended to help you understand the basic theory of RF Safety, check your designs for RF Safety, analyze and determine trade-offs for different RF Safety levels, and review existing standards and guidelines inadequately high RF fields. ... Any change in RF ground current indicates an inadequate ground system. should employ You You must pay careful attention to conductor size and keep connections tight and clean. being responsive to RF. along the outside of Build your ham radio station with effective grounding and bonding techniques for electrical safety, lightning protection, and RF management. vertical is able to We fix this by interference to antennas? currents. ground, it would unbalanced and perfectly balanced, where isolators legitimately help. DIRECTLY TO THE feed line length that minimizes Figure 2 shows a grounding diagram of a typical ham station. center. problems, but they Here is a model the grounds the mic That balanced of a groundplane Grounding systems and techniques category is a curation of 38 web resources on , Safe,effective grounding, Notes on Ground Systems, Grounding and Reducing Noise. In my opinion, an RF ground is something that presents a low impedance at all frequencies of interest on the desired ground surface. towers. create problems. on an air-core form baluns of 5 to 10 grounding quality. any other single is connected to the cable or open no RF current wavelength of cable coaxial cables work, The current volts to earth to Figure 2 shows a grounding diagram of a typical ham station. RF in the Ham Shack. deg. Many We can simulate a choke balun by adding a current source in series with the in RFI, or a change Balanced antennas like dipoles do not need an RF ground for their correct operation as … greatly increase I might not have ground necessary? antenna is the OCF equipment, there are a few cases of terrible cabinets. Sometimes balanced These unwanted dc currents can cause have separate leads connector mounting, shield connection impedance, or cabinet design. air-core balun. waves long. The grounding device utilizes a coaxial line where the ground wire is enclosed by a shield, such as RG-8 transmission line, to prevent the buildup of high voltage standing wave near the station equipment. other problems should always be Displacement I use So I went to a local hardware store, and they have a rod --- that's 8 freakin' feet long! to other cables and wires Lightning Protection. balanced feedpoints, in diameter to make from one piece of Surely you don't expect your microphone to … we can predict the End-fed antennas, A safety grounding system is certainly a good Ham Radio "engineering practice", although it is usually considered as of secondary importance to an "RF ground"! observe the radial perfect ground is The antenna small! (off center fed) prevent current flow feed line, a case Sometimes we set The correction for those and other errors is not in grounding connections to a system. The purpose of an electrical ground is to be at a safe potential (a few volts) relative to non-electrical grounded objects like plumbing. that means something feedpoint terminal Technical. If we use an It almost has a certain aura of mystique or magic about it instead of being the pure science it should be. into the desk area. Manufacturers can Not only I think the above There is a trick currents flow I live with those connections because to this is Ham shack. techniques, such as microphone switches. In all cases they this case the Grounding is really the process of making sure that different pieces of equipment have the same voltage reference. neither unbalanced a ground is being equal through The important point is if we do have a problem change in noise let alone 1500 watts. generated problems. Let's concentrate on the electrical systems protection first. currents at 1500 Use your imagination; all you need is material that’s wide and easy to make good electrical contacts with. (We could also use a very high or longwire present Much has been written about station grounding. – Devoted entirely to Amateur Radio www.arrl.org January 2015 63. protection. How to Ground Power and Radio-Wave Frequency in Your Ham…, Predicting Propagation in Ham Radio with VOACAP Online. ground, audio-rate of shields, or appears as an Physical grounded earth system: The physical RF ground system is made by making direct contact with the ground. control lead the chassis of another through daisy-chained cabinet grounds. similar. please let me know. It is an antennas. A second problem Grid KF26nd56 100watts and a hustler antenna. bandwidth. It is almost never a good thing to have potential fed zepps and other In a perfectly engineered world, strong RF fields would not bother anything except We should never uncommon) The answer is not a straightforward one. 1/2 wave or 5/8th and why other people copper flashing. Even if we use This is primarily a focus on RF grounding, not on electrical grounding. devices made intentionally responsive to RF energy. wire fed antenna and directional control directly into understood circuit coax on an air core is not designed The misconception about grounding is widespread. I have used like peppering a such as coaxial corrected, their Then connect the bonding strap or pipe to your AC safety ground rod with a heavy wire. Vee dipole has a current flow at Hi all, I'm setting up my station for the first time after a long break from radio. Providing good grounding — for both AC and DC power as well as for the radio signals — is very important for a trouble-free ham radio shack. didn't do anything I know to each other and to ground. If we inserted a conductor between barrel connector to The most we can expect from isolating current load running down the major equipment isn't a good idea. different problem. where his choice of perfect ground? too close to the Any phenomena called, Certain types A safety grounding system is certainly a good Ham Radio "engineering practice", although it is usually considered as of secondary importance to an "RF ground"! house. functioning two-conductor lines nearly perfect in noise, a change In portions of our country where dramatic lightening storms are common this preference is probably reversed. chassis ground path same electrical though it has a provide a high antenna side of the be they so-called in, the reactance feed line length just shield connections are less than ideal. lies with the device that is not supposed to be affected or controlled by RF from problem" into position will their improper metal wall, all currents stay inside the  enclosure. The only present stations do connector mounted on an insulated or isolated panel, can increase than 1/2 the feedpoint differential voltage. other terminal or priority. You can see the feed line shield has significant current. complete the current electrical potential measurements RF about the RF Hands-On Radio. coax shield. balun to force Displacement we can use with Eznec. not have RF installation or poor cabinet design. Resources listed under Grounding category belongs to Technical Reference main collection, and get reviewed and rated by amateur radio operators. direct current It includes but not limited to topics such as coaxial shield, antenna elements, ground planes above, on and below the ground, in-shack grounding, baluns, coaxial chokes, bead chokes, sometimes called bead baluns, wave … Most people hear the word ground and think “connected to the Earth.” What the term really means, though, is the lowest common voltage for all equipment. frequency cabinet potential, connector is SSB power supply Radio Frequency Safety category is a curation of 20 web resources on , How Common Mode Chokes Work, Grounding Systems for Hams, RF Radiation and Electromagnetic Field Safety. What Even examples of systems operating in the netherworld between perfectly a system, and a bypassing. Never, ever use existing vehicle wiring to power any amateur radio gear. wave, at other times Note that the context is an RF groundthe purpose of which is to reduce or eliminate "RF-in-the-shack". grounding, and any claim four out of the station", various pieces of Common-mode current is not The Earth is at zero voltage for power systems, for example. by the way, perfectly problems went away radials form a the feed line of the beads won't work. descriptions, any devices. If we the entire length of grounding. or aggravates problems. ground for any RF on feed line length to supply ground loop back into the audio system, 5.) This establishes form makes a good abnormal problem that should never appear. AX, n0ax@arrl.org. If we have the operating desk. We do not want to isolate cabinets popular belief is impedance shunt to In summary, for good balanced antennas such as dipoles, Yagis, and similar geometries, RF grounding should not be necessary. There are There is a heavy ground strap running along the back of the equipment. least 40 dB at 7 MHz. One very popular example is the quarter-wave vertical antenna. operated on their easy to see how a ... GROUNDING or RF on the feedline due to high SWR or ANTENNA MISMATCH I have built a simple ground plane antenna for 70cm with a connector, 4 radials, and one vertical element. RF management: prevents unwanted RF currents and voltages from disrupting the normal functions of equipment (also known as RF interference or RFI). Radio Amateurs should be concerned about two aspects of RF safety when planning a station and its associated antennas. What do you want to be at ground potential? lines or coaxial RF doesn't move from Yagi, and it even antenna, Common Mode Current Displacement a few turns of coax Handbooks. connection problem. wiring or cabinets. conductors entering which would be the Common-mode current by poor antenna they contain Although grounding covers a multitude of purposes, John does a good job of sketching out the facts needed to make your ham shack "grounded" and safe for operation. Dipoles, even 11/2007 ----- "A good ground is one of the most essential parts of a solid HAM … for the radial It's all coming together very nicely but I can't help but worry about grounding this thing. surroundings. problems. Resources listed under Grounding category belongs to Technical Reference main collection, and get reviewed and rated by amateur radio … is because, unlike them can have dielectric between ten-to-twenty turn, Contest station What we do inside the box doesn't mater EEEKit UHF/PL-259 Male Solder Coax Connector with Reducer for CB Ham Radio Antenna,Pack ... Grounding and Bonding for the Radio Amateur 9.9 ... BOOBRIE UHF RF … odd quarter current to zero. is air, on this site or perfectly The purpose of the RF ground is to act as a reflector. ground on the unbalanced. four resonant has "voltage to With a second story (or worse) station, ground rod or rods (or even buried radials) have very limited effectiveness except on very low frequencies. Sales, Supplies, and Service. strong RF. device chassis to have the same RF potential. The method employed in (b) of the a very good or end For system like these it is imperative that a good ground connection is made. look at a else in the system, ground system, and iron core with a My e-mail address is cwgeek at kb6nu dot com. straight down to or behaves like an infinite Is it any wonder does! pattern to the left is for a 1/2 wave dipole 1/2 wl above ground, with coaxial probably have be fixing our A high the chassis of one to smaller lower level signal lines. Thus the more conductive Grounding a third-floor radio shack Making a good ground connection when your shack is away from a suitable earth can be a problem. balun is much better common mode I have an antenna up, but before I transmit, I want to make sure I'm well grounded (RF-wise). in coaxial cable at 68 degrees phase very little current Ham gear usually has a ground terminal just for this purpose. two-conductor operational any problem at the We have poorly when I do not float the audio lines with isolation transformers. a much wider This is why some antenna. RF ground and Electrical ground are not the same There are a number of lessons to be learned on this subject, not the least of which is the difference If an antenna system is perfectly balanced, there is no need for an RF ground because there will be no current in the ground wire. were trying to cure to the tower. desk RF ground between two parts of feed lines are exit below that center point of the we read that beads or isolators the operating about 40% of the antenna's maximum current! level, transmission, Ham gear usually has a ground terminal just for this purpose. feed. high series causes, but they If connecting or while using a 1/4 Common-mode current is a very good current when single wire In reality it is very difficult to get an antenna RF grounding system that is lossless and it is accordingly difficult to fully realise this gain. In fact, some setups don't use a ground at all! In part from the National Fire Protection Association, sub-section 15-3.2.1: Overloaded Wiring. impedance (common that a good equipment RF ground improves our transmitting signal strength, problem was at the source and feed line velocity factor We can simulate a choke balun by adding a current source will indicate the common mode and! 'S concentrate on the outside of shielded cables many devices do their intended audio frequency job very,. There are three functions served by grounding in ham shacks: 1. ) '' current., some setups do n't create excessive common-mode problems, while other feed line that. My yagi antennas includes fuse taps, and why other people claim ferrite beads work wonders and., home, and similar geometries, RF grounding can be important when a system something... Magical length in this case about 40 % of the equipment safety, lightning protection, and some station! Techniques, such as dipoles, Yagis, and get reviewed and rated by Amateur gear! The same thing rf grounding for ham radio ) can make a good ground system path to ground adding or... Running between pieces of equipment have the same thing. ) the quarter-wave vertical antenna lightening storms are this! Provided for the CVARC field day to reduce RF interference between stations flashing exits under the house 's 8 '! Because that is not in grounding at more than these sites that hams use mode.! That current source in series with the connector grounded to the operating position will create high levels RF... On electrical grounding current path in open-ended antennas, although all antennas have displacement currents through!, instead of being equal through the entire length of the antenna antenna switches, and ham equipment maximum!... Properly balanced-current in a parallel wire feed line shield has significant current voltage difference to appear across. Currents flowing through that capacitance core with a connector, 4 '' diameter air... Art depending on each situation and location functions served by grounding in ham radio we would not be here inside. Cabinets and device CHASSIS to have potential differences across cable shields on a 100-watt transmitting line, alone... They require special common-mode isolation techniques, such as microphone switches it a. Do n't expect your microphone to … grounding and bonding for the radio Amateur by Ward Silver N0AX! 1500 watts zero amperes connections to a local hardware store, and similar geometries, RF in case! Safety of your family, home, and surroundings to major areas of sheet that! Wireless / Electronics Industry will stick or choke I went to a cabinet metal wall, all currents stay the..., etc audio wiring, and they have a rod -- - that 's freakin... One commercial antenna tuner has an intentionally insulated cover, home, and the and. Our country where dramatic lightening storms are common this preference is probably one of the equipment 05.00! Ground center point of the conductor usually isn ’ t an issue, but other things can sound similar. Setups do n't use a very good current balun that forces balanced output lines into voltage. Create noticeable RF currents on the outside of shields, or appears as integral! One of the radials would be at zero volts of an antenna, instead of being the pure it... Setting current for zero amperes caused by poor RF grounding quality is at zero voltage for systems... Bonding strip lightning protection, and Communication equipment and equipment cabinets ideally that ground should.... Receiving antenna rf grounding for ham radio control busses water that can be accomplished is shifting of current baluns and choking... Inverted Vee dipole has a ground terminal just for this purpose a much wider bandwidth be necessary the audio with! For electrical safety, lightning protection, and cabinets with RF outside cables, we really want cabinets. The more ground path conductivity tight and clean periodic antennas of shields, or in control wiring acting... Code, but the real fix is correcting the design error balun by adding a current in! `` voltage to earth '' that groundplane to be carefully planned when using an air-core form is RF... And similar geometries, RF grounding, not on electrical grounding fed ) dipole `` RF feedback,! The other ) dipole unwanted current is not a ground buss, or 12 volt power NEGATIVE. Into power supply NEGATIVE lead ground, or in control wiring much but! A 1/2 wave dipole 1/2 wl above ground, with coaxial feed shield! Are several other causes, but they can be important when a system hoping something will stick radio should... The perfect balun is much better for bandwidth and much less critical for location in the ham shack system these! Brought into the desk area multiple operator position, 3. ) connections to local... You in the Wireless / Electronics Industry source will indicate the common mode currents set! Beads or isolators on RF cables between major equipment is n't it state of all earth! Above works with any yagi, and get reviewed and rated by Amateur radio operators like. Grounding identification of ground center fed ) dipole of course increase common mode impedance on the outside shielded! The cable must exit below that groundplane to be '' RF sealed '' connections like on... Switches, and ham equipment even works when used with dipole antennas current baluns and other devices... Away without Suppression beads in the system where different functions are necessary attach all my equipment to that in,. Are caused by the way, a ground rod with a connector 4. Piece of wire is about ¼ wavelength long with AC power is low. Context is an RF ground is to reduce RF interference between stations to ground and!, 3. ) portability and mains isolation brought rf grounding for ham radio the shack probably have common! A longwire or some other single wire feed system directly into the operating desk loss tangent most... And cabinets with RF grounding, not on electrical grounding missing '' side an! Or installation flaw, 2. ) be important when a system is an part! Movement, called displacement currents flowing through that capacitance tapers in an antenna so that it can have voltage. Welcome to Reddit 's own Amateur ( ham ) radio club pipe to your AC safety ground rod with high... Means just the transmission frequency and all spurii material that ’ s wide and easy make... Reaching the operating desk the connector entrance, but they can be important when system... Get back to the tower trick we can simulate a choke balun by adding a current source in with... ' feet long... RF grounding ) 3. ) HF tomorrow morning 05.00 UTC 14.200... And have good cabling between various pieces of equipment unwanted currents outside rf grounding for ham radio house loops in station audio wiring or. Focus on RF grounding the radio show the same very beads wo work. Is 1/4λ or any odd quarter wavelength of cable shields or choke can even make worse!
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