Passive antennas cannot be overloaded by strong local stations, they do not produce intermodulation products, have mostly less problems with static charges and are lower in costs than good active antennas. There are also disadvantages. Some of them are large and sufficient outdoor space is required to mount them, although RF Systems produces also a number of small indoor passive antennas. For reception of stations at long distances (DX) the height of the antenna is very important: how higher the better. Standard antennas such as dipoles are in fact single frequency antennas and an antenna tuner is required to obtain good reception at other frequencies than the resonance frequency. This is also valid for the so-called multi band antennas: these have several resonance frequencies, mostly the amateur bands. For good results on other frequencies again an antenna tuner (matcher) is required. The use of an antenna tuner is un-handy and makes computer- or memory control of the receiver mostly impossible. That's the reason that all RF Systems passive antennas have built-in passive matching networks, which makes them wideband antennas with 50 ohms impedance. This also allows the use of coaxial cable between the antenna and receiver. This reduces interference pick-up and allows to hang the antenna far away from noise sources such as computers, TV sets, fluorescent lighting and other interference producing equipment.
The passive antennas of RF Systems come completely assembled, ready to hang and can be divided into 3 groups: outdoor antennas, indoor antennas and MT type stick antennas, mentioned for locations with very little space as available on yachts, campers and balconies on flats or other buildings.
OUTDOOR ANTENNAS
* MLBA Antennas MK1, MK2, MK3 and MK4
These are short (12.5 mtrs and 20 mtrs) end fed wire antennas (mostly called longwires), with built-in Magnetic Longwire Balun. Frequency range 100 kHz - 30 or 40 MHz, 50 ohms impedance, reduced noise pick-up
* T2FD Antenna
This is a 15 mtrs long travelling wave antenna for the 3 - 35 MHz frequency range. It is a low noise antenna, because it suppresses static noise. This is an ideal antenna for locations with a high man-made noise level. The output level is a little-bit lower compared to that of long wires, but the noise level is much lower, resulting in a better signal to noise ratio compared to longwires or trap dipoles. Many listeners see this as the best passive listening antenna for
shortwave. RF Systems' T2FD antenna is mentioned for receiving purposes only.
* WFL Antenna
The Wideband Folded Loop (WFL) antenna is a closed loop antenna with a circumference of 32 mtrs, folded in such a way that the outer dimensions are just 7.5 x 1 mtrs. This makes it possible to hang the antenna on nearly any location. The WFL antenna is wideband matched and covers 1.8 to 30 MHz, although the antenna can be used to 54 MHz. Like the well-known circular magnetic loop antennas the WFL suppresses man-made noise and is ideally suited for locations with a high interference level like industrial area's and in cities. The antenna can be used for receiving and transmitting on any frequency between 1.8 and 30 MHz without tuning. The VSWR in the amateur bands is lower than 1.7 : 1, so mostly no antenna tuner is required. The WFL antenna can handle up to 100 Watts p.e.p.
INDOOR ANTENNAS
In many countries outdoor antennas are forbidden. RF Systems passive indoor antennas form a good solution. They are however weatherproof and very unobtrusive, which makes it also possible to hang them nearly invisible on a small balcony or under a rain-gutter.
* EMF Antenna.
This antenna is just 5 metres long, with 5 metres coaxial lead-in cable to the receiver. Frequency range 100 kHz - 30 MHz, impedance 50 ohms. This antenna makes use of the electrical- as well as the magnetic field component of the radio waves and gives therefore despite its short length, good low noise reception of the long-, medium- and shortwave bands.
* MINI - WINDOM ANTENNA
This is a low-cost wideband miniature receiving antenna with built-in matching transformer. The length is just 4 metres, frequency range 500 kHz - 30 MHz. It offers omni-directional, low noise reception without intermodulation. It's ideal for apartment dwellers and on holidays. Lead-in coaxial cable with a length of 4 metres, 50 ohms impedance.
PA - 30 low cost wire antenna
Often receivers are used with just a few metres of wire (random wire antenna) The lack of a good ground results in noisy and mediocre reception, especially with portable receivers. The PA - 30 is a wideband, passive wire antenna for long-, medium and shortwave with a length of 4 metres, transformer matched to 4 metres of coaxial lead-in cable, which is used as counterpoise. The reception results of this antenna are much better compared to a random wire antenna of the same length. The antenna is ideal for holidays and apartments if costs are an important factor.
MT ANTENNAS
Magnetic Transfer (MT) antennas are the smallest wideband passive receiving antennas in the world. These are stick type antennas with a length of 2 m or 1.25 mtrs and a diameter of 32 mm. They do not require a ground plane and are mentioned for on board of ships, campers and on balconies in apartment buildings. They are build to withstand any climate including hurricane area's. For even better results, they can be combined with the *WA- 50 antenna amplifier* to form a very high performance, low-noise antenna system.
* MT Antenna.
Just 2 metres long, 32 mm diameter. No ground plane or antenna tuner required, 50 ohms impedance, frequency range 500 kHz - 30 MHz, mentioned for general listening purposes.
* GMDSS Antenna.
Originally developed for on board of ships for the GMDSS system, but also very useful for general long-, medium- and shortwave listening. Gives 6 dB more output from 100 kHz - 2 MHz than the MT antenna, equal from 2 - 25 MHz, but 6 dB less above 25 MHz. Just 2 mtrs long, 32 mm diameter, 50 ohms impedance, no ground plane or antenna tuner required.
* GMDSS - 2 antenna.
The smallest wideband passive antenna in the world. Just 1.25 mtrs long, 32 mm diameter, 50 ohms impedance, no ground plane or antenna tuner required. Frequency range 500 kHz - 18 MHz, but the antenna can be used with slightly reduced output to 30 MHz.
The passive antennas of RF Systems come completely assembled, ready to hang and can be divided into 3 groups: outdoor antennas, indoor antennas and MT type stick antennas, mentioned for locations with very little space as available on yachts, campers and balconies on flats or other buildings.
OUTDOOR ANTENNAS
* MLBA Antennas MK1, MK2, MK3 and MK4
These are short (12.5 mtrs and 20 mtrs) end fed wire antennas (mostly called longwires), with built-in Magnetic Longwire Balun. Frequency range 100 kHz - 30 or 40 MHz, 50 ohms impedance, reduced noise pick-up
* T2FD Antenna
This is a 15 mtrs long travelling wave antenna for the 3 - 35 MHz frequency range. It is a low noise antenna, because it suppresses static noise. This is an ideal antenna for locations with a high man-made noise level. The output level is a little-bit lower compared to that of long wires, but the noise level is much lower, resulting in a better signal to noise ratio compared to longwires or trap dipoles. Many listeners see this as the best passive listening antenna for
shortwave. RF Systems' T2FD antenna is mentioned for receiving purposes only.
* WFL Antenna
The Wideband Folded Loop (WFL) antenna is a closed loop antenna with a circumference of 32 mtrs, folded in such a way that the outer dimensions are just 7.5 x 1 mtrs. This makes it possible to hang the antenna on nearly any location. The WFL antenna is wideband matched and covers 1.8 to 30 MHz, although the antenna can be used to 54 MHz. Like the well-known circular magnetic loop antennas the WFL suppresses man-made noise and is ideally suited for locations with a high interference level like industrial area's and in cities. The antenna can be used for receiving and transmitting on any frequency between 1.8 and 30 MHz without tuning. The VSWR in the amateur bands is lower than 1.7 : 1, so mostly no antenna tuner is required. The WFL antenna can handle up to 100 Watts p.e.p.
INDOOR ANTENNAS
In many countries outdoor antennas are forbidden. RF Systems passive indoor antennas form a good solution. They are however weatherproof and very unobtrusive, which makes it also possible to hang them nearly invisible on a small balcony or under a rain-gutter.
* EMF Antenna.
This antenna is just 5 metres long, with 5 metres coaxial lead-in cable to the receiver. Frequency range 100 kHz - 30 MHz, impedance 50 ohms. This antenna makes use of the electrical- as well as the magnetic field component of the radio waves and gives therefore despite its short length, good low noise reception of the long-, medium- and shortwave bands.
* MINI - WINDOM ANTENNA
This is a low-cost wideband miniature receiving antenna with built-in matching transformer. The length is just 4 metres, frequency range 500 kHz - 30 MHz. It offers omni-directional, low noise reception without intermodulation. It's ideal for apartment dwellers and on holidays. Lead-in coaxial cable with a length of 4 metres, 50 ohms impedance.
PA - 30 low cost wire antenna
Often receivers are used with just a few metres of wire (random wire antenna) The lack of a good ground results in noisy and mediocre reception, especially with portable receivers. The PA - 30 is a wideband, passive wire antenna for long-, medium and shortwave with a length of 4 metres, transformer matched to 4 metres of coaxial lead-in cable, which is used as counterpoise. The reception results of this antenna are much better compared to a random wire antenna of the same length. The antenna is ideal for holidays and apartments if costs are an important factor.
MT ANTENNAS
Magnetic Transfer (MT) antennas are the smallest wideband passive receiving antennas in the world. These are stick type antennas with a length of 2 m or 1.25 mtrs and a diameter of 32 mm. They do not require a ground plane and are mentioned for on board of ships, campers and on balconies in apartment buildings. They are build to withstand any climate including hurricane area's. For even better results, they can be combined with the *WA- 50 antenna amplifier* to form a very high performance, low-noise antenna system.
* MT Antenna.
Just 2 metres long, 32 mm diameter. No ground plane or antenna tuner required, 50 ohms impedance, frequency range 500 kHz - 30 MHz, mentioned for general listening purposes.
* GMDSS Antenna.
Originally developed for on board of ships for the GMDSS system, but also very useful for general long-, medium- and shortwave listening. Gives 6 dB more output from 100 kHz - 2 MHz than the MT antenna, equal from 2 - 25 MHz, but 6 dB less above 25 MHz. Just 2 mtrs long, 32 mm diameter, 50 ohms impedance, no ground plane or antenna tuner required.
* GMDSS - 2 antenna.
The smallest wideband passive antenna in the world. Just 1.25 mtrs long, 32 mm diameter, 50 ohms impedance, no ground plane or antenna tuner required. Frequency range 500 kHz - 18 MHz, but the antenna can be used with slightly reduced output to 30 MHz.
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