Once the dominant form of all communication and home entertainment, the radio has fallen on hard times, being relegated to the automobile or the personal, portable units strapped to the waistband of your jogging suit.  Nevertheless, it continues to inform and entertain unlike any other medium. Most consumers, however, voting with their wallets, have turned away from the separate FM tuner. As a consequence, there are fewer and fewer tuners to select from, and finding one at a retailer can be even harder. It is possible to have a Tuner built into an amplifier and is usually referred to as a Receiver or a Tuner Amplifier.  With the growing interest in Home Theatre equipment - Receivers are now more popular than ever. The truth is that FM stereo offers opportunities for thrilling sound sources which no other medium has, including satellite sources which claim state-of-the-art sound but can't really deliver it yet. FM stereo reception can be reference quality- providing you with a direct feed of music played live the moment you hear it, and usually from venues in your locale. If the Symphony is your cup of tea, there's probably a station near you which will carry it. And popular music stations carry live, in-studio appearances by big name performers as a matter of course. These represent the only possibility for bringing reference quality live performances into the comfort and convenience of your home. In many cases, thrilling television performances are simulcast on FM. Enjoying such landmark performances as "The Last Night Of The Proms" from the Albert Hall each year on your system is only half-realized unless you had a first-rate tuner to match the first-rate picture of your video equipment. The sound quality that your television or VCR tuner can provide, while acceptable for mass "mid-fi" applications, is not even remotely as good as that possible with one of today’s state-of-the-art FM tuners. When coupled to a sound system of commensurate quality, the shortcomings of such "compromise" systems become acutely obvious. Separate tuners are also perfect for systems that change often. You have the flexibility to upgrade any component and keep your tuner where it is. As with all the audio components, better internal circuitry and build quality deliver a better audio signal to your system. If you like to record programs off-air and want to build a library of rare recordings, a great tuner and antenna system is a great investment. WAVEBANDS There are currently three main wavebands in use for domestic radio broadcasting.  Medium Wave (Mw.  Often wrongly referred to as AM) Long Wave (Lw) Very High Frequency (VHF) also wrongly referred to as FM Digital Audio Broadcasting (DAB or Digital Radio)   MW / LW Bands These two wavebands are broadcast using a tried and tested system called AM (Amplitude Modulation).  The technicalities of which I don't intend to cover at the moment.  Suffice to say that AM broadcasts are very prone to interference from many wide and varied sources. The major benefit of these bands is that broadcasts generally have a wide coverage from a single transmitter.   Because of this it is ideally suited for use in car radios and portables. During the daylight hours reception is limited to mainly local (80mile radius) station, when night falls the distance is extended greatly (4-500miles).    The real drawback for HiFi users is that broadcasts in AM tend to be of a poor quality and in Mono only.   Also antenna's for the MW/LW bands are extremely large!   VHF / FM Band Broadcasts on the VHF band are now all broadcast using the FM (Frequency Modulation) mode and as such provide a good format that is relatively free from background interference and also interference from other stations. On a VHF system it is essential that a good antenna be connected to the tuner for best results.   The wires and T-Shaped antennae normally shipped with a tuner are more or less worthless unless you live within five miles of the transmitter.     Antenna's and other obstacles to consider   Ron Smith, Galaxie 23 antenna in action.    Photo Mick Evans 2000   The selection and installation of an appropriate FM antenna is arguably the most important aspect of receiving high quality FM broadcasts. No single antenna type, whether indoor or outdoor, is perfect for all receiving situations. Before purchasing an FM antenna you must decide what type you really need. Define the problems you need to overcome and consider your location. The key to good FM/stereo reception is to get the maximum direct signal from the transmitter and minimum amount of reflected signal. Even though a common outdoor television antenna may, in a few instances, provide acceptable results, antennas specifically designed to receive the FM broadcast band, generally 88 MHz to 108 MHz, are the most effective for FM reception. The FM broadcast signal is VHF (very high frequency) in nature and generally can only be received within a distance known as "line of sight or prime reception area" about 25 miles. Without hills, mountains, or buildings to impede its progress, an FM phenomenon commonly known as "diffraction" causes the FM broadcast signal to conform to the curvature of the earth for a distance of approximately 30 miles beyond normal line of sight. It is this phenomenon that provides for long distance or "fringe reception" of the FM broadcast signal. Fringe reception can usually provide a listenable FM signal, although it is often noisy and of low audio quality. If you live in a metropolitan area or are located close to an FM transmitter, an antenna with sharp directivity is needed rather than a high-gain antenna. A good FM antenna should reject unwanted signals coming from a different direction or bouncing off obstructions. Good rejection depends on the antenna's front-to-back ratio and beam width. Front-to-back ratio is the antenna's sensitivity to signals coming at its rear. The higher the ratio, the better rejection of unwanted signals coming from behind. The beam width indicates the angle at the front of the antenna within which it can best receive the FM signal. A narrow beam width makes it difficult for unwanted signals to be received from the side.
The communications tower located at Emley Moor.   Owned and operated by NTL	From 2 to about 25 miles out is what is referred to as the "prime" FM reception area. Here, multipath distortion is less of a problem, and a medium gain antenna with a moderate beam width should be perfect. However, if you wish to receive FM stations in different directions you'd probably want a directional antenna with rotator. From 20 to 40 miles out is the normal reception area, and an antenna with good gain is needed. Again, depending on the location of the FM transmitters, you may want a directional FM antenna with rotator. If you are located more than 40 miles out you are in the "fringe" area. You'll need a "hot antenna," that is, one with high gain. If stations come in at the same or adjacent channels the antenna must be directional. Again, a rotator may be required. If the antenna alone doesn't provide enough gain, the use of a masthead amplifier may be helpful.   Outdoor FM Antennas As a general rule, an outdoor FM receiving antenna that has many elements can be assumed to be highly directional. That is, it will be more sensitive to FM signals received perpendicular to its active elements than to signals arriving from other angles or even in the opposite direction. Such directionality is desirable in an outdoor FM antenna for mainly two reasons: Antennas that are highly directional usually have higher gain. Antenna gain will provide increased signal strength when receiving a transmitted FM signal. When referring to an FM antenna, gain is most often referenced to a standard half-wave dipole, such as a simple flat twin-lead antenna. For example, an FM antenna with an advertised gain of 3 dB will deliver to your FM Reference approximately twice the power compared to a standard half-wave dipole. A directional antenna will receive only those stations within the defined antenna beamwidth.  Antenna beamwidth is the general measure of the amount of directionality and is defined by the half power points (-3 dB) of the angle of the front radiation hemisphere. If the angle is too great (wide antenna beamwidth), the antenna will receive the desired FM broadcast as well as reflected signals (multipath) from different horizontal directions that may cause FM broadcast interference. Conversely, it may prove difficult to precisely position an antenna with a very narrow beamwidth for proper reception of the desired FM broadcast. An omnidirectional antenna, although much lower in gain and lacking any significant directionality, may prove to be adequate in a few applications. For example, if you live in an area which is relatively free of multipath problems and receives strong signals from many directions, a low-cost omnidirectional outdoor antenna may suffice.
Of the outdoor FM broadcast receiving antennas available, the following are most common: Unidirectional Dipole - This is a large dipole having two elements and slightly more gain than the common indoor twin lead dipole. It concentrates its signal reception mostly in one direction. This type of antenna could be used where the desired stations are in one general direction and within about 20 miles.   Turnstile (crossed dipole) - This antenna attempts to provide an omni-directional receive pattern, without the need for rotating the antenna. Omni-directional antennas do not discriminate with regard to direction. Thus, signals from all directions are received with equal strength simultaneously. This antenna is most useful in urban areas having reasonably strong signals coming from all directions and few multipath interference problems.  Unfortunately, one of the drawbacks of such a type of antenna is that it has relatively low gain (about -3 dB) in all planes. Multi-element Array - This is a unidirectional antenna capable of receiving very distant stations due to its high gain. However, this gain is directional and may in some cases require that the antenna be rotated each time you tune to a station (usually using an antenna rotator system). A good quality antenna of this type, mounted high on a mast in most suburban and rural installations, should provide you with the best FM reception possible. Yagis, collinear, and log periodic are the most common of these high-efficiency, multielement array types. Indoor FM Antennas -  For urban, near-suburban or in other situations where an outdoor antenna installation is not possible or desirable, a high-quality indoor FM antenna should provide excellent reception.  It should be noted that the urban FM receiving location poses a totally different set of problems than that of a suburban or fringe reception installation.  The radio frequency environment in and around modern metropolitan areas is jam-packed with voice and data transmissions, over modulated broadcasts, FM multipath, and out-of-band spurious interference, all competing for valuable airspace...spilling over and interfering with your favorite FM radio station.  Because the L-R portion of the FM stereo broadcast signal is more easily affected by this RFI and multipath than the L+R portion, stereo reception of even a very strong local FM station might be noisy and distorted, while monophonic reception of the same station is clean and clear.   To complicate matters, multipath signals in an FM urban environment are generally received from almost the same direction (in the horizontal plane); even a directional outdoor antenna with its horizontal angular discrimination is often incapable of separating the desired direct path signal from this vertically oriented multipath interference. Unamplified Indoor Antennas - There are two basic antenna configurations generally used in unamplified indoor antennas, both are dipoles. Bidirectlional Dipole - This is perhaps the most commonly-used indoor FM antenna. The single, 1/2 wave, dipole design exists as an industry gain reference (O dB) for most FM broadcast band antennas. The crudest form of a dipole is the "ribbon dipole" found packed with most FM tuners and receivers. 1/2 Wave Vertical - A 1/2 wave vertical design features relatively high gain for an indoor antenna, approximately twice the gain of the bidirectional dipole. The 1/2 wave vertical dipole is probably the antenna of choice for high quality FM reception in an urban environment. Cable FM Service - In most cases, cable FM (provided with some cable television services) is distinctly inferior in the areas of signal-to-noise, cross-talk and RF intermodulation distortion when compared to a properly installed FM antenna, whether indoor or outdoor.     ANTENNA GAIN The perfect antenna receives equally well in any direction. However, because the desired concentration is the above ground level, a way has been discovered to transfer the antenna's receptive capability from one direction and 'add' it, electrically, to the antenna's receptive capability in another direction. Thus the antenna's directional response and its efficiency are improved dramatically. The best example of this is the "multi-element" antenna referred to earlier. Here, they have taken a yagi design, which has the dipole antenna as its basic element, and added a reflector behind the dipole to establish a concentration in another direction. The reflector's location is now called the "back". To the front have been added 'director' elements that establish a tuned attitude towards an established band of frequencies. In this case it would be the FM band of 88 - 108 MHz. The antenna's directivity is further 'shaped' by moving its concentration, again electrically, to a more forward attitude. The result is an antenna that has been 'desensitized' to signals arriving at its sides and back and has been made ultra-sensitive to signals arriving at its front. The amount by which it has become more sensitive, in relation to that of a single dipole, is called 'gain'. In terms of signal voltage, each 6 dB of gain represents a doubling of the signal voltage over that received using the reference dipole. (in this context, the dipole is referred to as having 0 dB gain.)   COAXIAL CABLES There are two types of cable in general use for domestic, FM antennas. One is the flat, twin-lead cable that has been used since TV was first introduced. The second and most popular type is the 75 ohm coaxial cable; also referred to as RG59/U cable. Typical line loss for RG59/U is about 3 dB per 100ft at 100 MHz. More recently a 75ohm coaxial cable bearing the designation RG6/U has become popular. It is available in a single-shielded version and in a 'quad-shielded' (4 layers of shielding) version. This type of cable has a larger (18ga) center conductor and is capable of passing more signal. Therefore the line loss/100 ft. will be less than RG59/U. The RG6/U, 'quad-shielded' variety is right for the times as it offers maximum shielding against interference from extraneous interference from the likes of computers, CD players and other man-made interference-makers. However, while RG6/U has a similar spec. to RG59/U we do not recommend it be mixed with RG59/U in the same feed line. In fact, we offer this word of caution about coaxial cables in general. Do not mix different types of coaxial cable unless their technical specifications match exactly. ie. 'RG59/U-type' cable is not exactly the same as RG-59/U. Nor is cable labeled simply "75 ohm" to be regarded as the same as either of the previously-mentioned types. Speaking generally, the better grade of 300 ohm twin lead has about one half the losses that occur in coaxial cable. Unfortunately, its added efficiency is only of valuable in areas where interference is very low. Coaxial cable, on the other hand, provides (a) much better protection against interference pickup, and (b) a much easier and less expensive installation. The tradeoff of less signal for a quieter and less expensive installation is often well worth it. However, the rural listener who is not particularly bothered by local interference might want to take advantage of the higher signal yield offered by a good grade of 300 ohm twin lead when a long length run of lead-in cable is necessary. Typical line loss for a good grade of 300 ohm, twin lead is about 1.1 dB per 100 ft. at 100 MHz. Finally, would-be antenna installers should keep the following in mind as they plan their installation. The two major contributors to lasting installation efficiency are; (a) a neat, well-thought-out cable run and, clean, tight connections that have been protected against the elements. For coaxial cable, a little silicone grease on the connector shell threads will help guard against corrosive buildup. For 300 ohm twin lead, the avoidance of running the cable near metal is important. If the cable must go over eavestroughing, pipes etc., make sure it is kept a distance of at least 4 inches away to avoid picking up interference. The cable should also be twisted through 360 degrees for each foot of cable run to avoid becoming an antenna itself and detuning the system. N.B. The reference to 300 ohm cable excludes the shielded variety. This type has about the same loss factor as coaxial lead-in.       Multipath Distortion Multipath distortion is characterized by the specific distortion of 's' and 'z' sounds (sibilance) such that 's' sounds like 'shhh'. In its more serious forms it effects all the sounds to make them rough sounding or 'brittle'. It is caused, as the name implies, by the transmitted signal traveling to the receiver via more than one path: a common cause of this is reflection of the signal from hills or tall buildings, (see Fig 2). The reflected signal arrives at the aerial a moment later than the direct one because it has traveled further. The reflected and direct signals then interfere with each other causing distortion.  The best way to minimise multipath distortion is to use a directional rooftop aerial, ie. one which will only pick up signals coming from the direction of the transmitter, and will reject reflections which arrive at its sides or its back. It is also sometimes possible to mount the aerial so that the house screens it from the reflections but not from the wanted signal. If you have a multipath distortion problem with a portable radio try moving it to a different position in the room.    Adjacent Channel Interference Adjacent channel interference is interference from a channel which is close in frequency to the one on which you are listening. It sounds like a twittering noise in the background and is consequently sometimes known as 'birdies'. The problem is usually only apparent on stereo but if the interfering channel is very close in frequency, ie. only 50 or 100 kHz away, the effect may also be heard in mono. In the UK, the BBC's FM transmitter network has been designed to avoid such problems but if you are listening outside the published service area of the transmitter, or if there are rare atmospheric conditions, you could still suffer from this problem. As with most reception problems, a good directional rooftop mounted aerial will probably solve the problem, providing the interfering transmission is not coming from the same direction as the transmission you want. Some stereo tuners incorporate 'birdie' filters which use electronic circuitry to block out adjacent channels.   Overloading Overloading happens when a FM receiver receives too strong a signal. It should only be a problem if you live close the FM transmitting station. Overloading causes intermodulation distortion which is very rough and discordant and this in turn will cause twittering 'birdies' in the background. The distortion will be present both in stereo and in mono. The cure for overloading is to add an attenuator between the aerial and the receiver. Attenuators are available from radio and TV shops and they are easily plugged in between the aerial and the aerial socket. They come in various values, quoted in decibels (dB), and your dealer should be able to advise you on the correct amount of attenuation you require.   Lightning Protection Something that you need to be aware of is that there is no such thing as 100% protection from lightning strike. And, to be honest, there is nothing I can tell you that will provide even 1% protection against lightning strike. As have been chronicled on the "Extreme Weather" documentaries appearing on The Learning Channel of late, lightning can strike at the most inopportune time and in some of the least-expected places. However, like 'preventive maintenance' for your car, there are things one can do to reduce the the possibilities of lightning being attracted to your antenna. Of course, the best protection is to disconnect the antenna from the tuner whenever storms are evident. One of the attractions for lightning is the considerably reduced potential difference between the clouds and the ground offered by a building, a tower, or a tree. This would obviously include an antenna. Making that even more attractive as an appropriate path is the static buildup that occurs in an antenna as a result of wind friction. It is the 'static buildup' factor we are attempting to reduce by grounding the antenna, thereby making it somewhat less attractive to lightning . While trees that closely surround a house, if they are about 25 - 50% taller than the antenna's above-ground height, might offer an easier strike target than antenna, there is nothing to stop some of the strike from arcing over to the house, if parts of it are seen as a better path to ground. The parallel to that is one of the reasons one should not stand under a tree during a storm. A person, with their salt-rich body fluids offer a much better course to ground than would that of a big tree. The other danger is having the tree explode into you.   Some grounding techniques include ensuring that the base of the antenna (shell) is physically connected to ground. Another is to run the coax through a "static discharge block" which is connected directly to earth ground. This may reduce the amount of signal slightly by virtue of insertion loss, but it does offer a better path to ground to dissipate static buildup. Another preventive measure you might take is to ensure the coaxial cable is not run alongside metal surfaces, such as eaves troughing and ice fences, etc. (mounting mast and tower excluded), which might be a more obvious path for a lightning discharge, should one hit. I realize in all of this that I might have gotten you thinking twice about putting up an antenna at all. Also, it would be very easy to offer the more political "no comment" to your question. However, I hope the foregoing does shed some light on the subject for as many as want to know. Finally, there are millions of antenna installations that exist around the world with the larger percentage of them never having been bothered by lightning. Just bear in mind that lightning is far from predictable and the more wary you are of its significant power, the more cautious you will be about placing yourself, your family or your hard-earned possessions in harm's way.

Ron Smith - Orion 10 Antenna in action

Mick Evans 1999-2001

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