Frequency Range 2 - 32 MHz Model 3R/4E26 provides complete 360º coverage in azimuth, by employing three 4E26 Aperiodic Loop Antenna Arrays in a radial configuration or Rosette. This arrangement is possible because of the low mutual coupling between individual elements which enables the arrays to be placed close to one another. Outputs are taken simultaneously from each end of each array to provide full omnidirectional coverage.
The 3R/4E26 comprises three Model 4E26 Aperiodic Loop Antenna Arrays arranged at 60º to one another.
The performance of each array is identical to the specification for Model 4E26. Receiver outputs are provided in six 60º sectors with four outlets available for each sector. (Additional ...
Frequency Range 2 - 32 MHz Model 4E26 consists of 4 individual loop preamplifier elements arranged in an 'end-fire' configuration using an inter element spacing of 26 ft. (8 meters). This arrangement gives a unidirectional characteristic up to 15 MHz. Above this frequency grating lobes appear limiting the directional gain, however, the main beam characteristics are optimum over the whole 2-32 MHz range. The elevation characteristics are optimum for both long and short haul communications via the ionosphere, due to the 'opening up' of the elevation pattern at lower frequencies.
Linear Arrays First numbers indicate number of elements in array. Next letter indicates type of array. i.e., 'E' ...
Frequency Range 2 - 32 MHz Our basic antenna is an untuned, balanced loop which has dimensions that are small compared with the wavelength. A preamplifier circuit, fitted at the base of the antenna, exactly complements the loop characteristics. This combination results in a nominally constant, effective, height over the 2.0 to 32.0 MHz frequency range.
At frequencies less than 30.0 MHz it is possible to employ an antenna for receiving purposes which is electrically small and has poor free-space coupling efficiency, without prejudicing the overall system noise factor. This is because the antenna output noise comes primarily from atmospheric and galactic sources. The thermal noise introduced by the antenna radiation ...
Frequency Range 2 - 32 MHz Model 8E13 consists of 8 individual loop/preamplifier elements arranged in an 'end-fire' configuration. The inter element spacing of 13 ft. (4 meters) has been chosen to be less than λ/2 at 32 MHz, giving a good front/back ratio for the array up to this frequency.
The elevation characteristics are optimum for both long and short haul communications via the ionosphere, due to the 'opening up' of the elevation pattern at the lower frequencies.
Linear Arrays First numbers indicate number of elements in array. Next letter indicates type of array. i.e., 'E' endfire. Next numbers indicate inter element spacing in feet.
This model is designed for quick erection at a site, and to pack into the minimum transportation volume. The electrical performance is identical to the standard loop antenna, and is equally suitable for permanent or temporary installations.
The illustrations show the way the half loops fold over one another, and the flexible transmission line coils up for transport.
Each element, complete with 13 foot transmission line and support, occupies 45" x 16" x 6". Weight, unpacked, of a four element array is approximately 150 pounds. Individual loop assemblies can be packed individually or in groups as required by the customer.
This unit provides the DC power to the preamplifiers, via the coaxial cable connecting the array to the receiver building. It includes a multicoupler enabling a maximum of four receivers to be operated independently and simultaneously from a single array.
The DC power output circuit is current limited to prevent damage due to short circuit conditions, and includes an ammeter showing the total current drawn by the array preamplifiers. This provides an indication of fault condition in a preamplifier.
The test set LTS 12 provides facilities for performing radio frequency and direct current tests of each loop antenna.
The test set is provided with a self-test facility and may, in addition, be used as an uncalibrated field test meter. Radio frequency tests of individual loops are performed by radiating a signal into the loop from the test set.
Inserting the probe assembly into the base of a loop antenna connects it to the +24 VDC antenna system supply and provides power for the Test Set.