LOS/Satcom Superdirective Endfire Array Feeder (2-way Phasing Splitter/Combiner) description
The SPLU-3002-711 is an UHF Line of Sight (LOS)/Satcom Superdirective Endfire Array Feeder (2-way Phasing Splitter/Combiner) designed to produce a Supergain Endfire Array from two constituing elements directly mounted at its output ports. You can obtain an approx. 5 dBi unidirectional beam antenna by connecting two identical or similar omnidirectional antennas at each output.
The terms "Superdirective" and "Supergain" used here, or in the literature, are not marketing hype or jargon: they refer to a simple endfire array phasing optimization recipe published by Hansen and Woodyard in 1938, producing nearly maximal gain [Hansen, W.W. & Woodyard, J.R. (1938). "A New Principle in Directional Antenna Design". Proceedings of the Institute of Radio Engineers, 26, 333-345.] Their recipe offers the most benefit to endfire arrays of few elements, which gave us the idea of offering a tool enabling users to share resources in the field for mission enhancement. Thus, field operatives may improvise a nearly maximal gain directional array ad hoc, simply by adding their 2 identical antennas (normally omnidirectional radiating structures). In this light: a union of 2 omnis that creates a greater force of approximately +5 dB (3x signal magnification, TX & RX).
An example of a Superdirective Endfire Array improvised with an SPLU-3002-711 Combiner is pictured above (photo 2). In this example, it is pairing two of our UL-3001-340SN UHF Satcom linearly polarized models. This combination produces a unidirectional beam with a passive gain of at least +4 dBil (+5 dBil typical) across the entire UHF Satcom band. Any other pair of linearly polarized antennas may be similarly connected to produce a directional beam +5 dB above the gain of each individual element. The SPLU-3002-711 has an arrow marking the direction of maximum radiation.
The SPLU-3002-711 may also be used to merge two hemispherical circularly polarized antennas to improve the satellite link. However, such combination requires a little more care. The simplest combination entails using two identical RHCP elements, such as our UC-3004-481R Tacsat antennas, connected to the Combiner using 2 right angle N adapters at each end, enabling the 2 elements (antennas) to point in the same direction and orientation. This combination produces an RHCP +5 dBic directional array. Alternatively, one may combine RHCP and LHCP elements directly plugged into the SPLU-3002-711 output ports. The RHCP element should be the one pointed to by the Combiner's arrow. In all combinations, the orientation of the circularly polarized elements is important, as they will change the phasing of the array (a 3/4 chance of not getting it correctly if not paying attention).
If the improvised array is receive-only, the addition of our LNAU-0255-648 or LNAU-0370-648 will add another +20 dB of active gain at a low Noise Figure, to produce a total receive gain of +25 dBi. They also introduce filtering to protect and beneficially condition signals in Software Defined Receiving systems.
For additional information on other antenna combinations and improvisations, or for any questions, please feel free to contact us.
SPLU-3002-711 Technical Specifications
- Frequency range: 240-380 MHz
- Phase difference between ports: Stabilized Hansen-Woodyard phasing (Arrow points to maximum)
- Nominal Impedance: 50 ohm (RF) / Short Circuit (DC)
- Input Power: 50 Watts CW Maximum
- VSWR: 2.0 Maximum
- Connector: Type N Female on all ports
- Dimensions: 21.0 cm (8.3") L x 6.4 cm (2.5") W x 4.5 cm (1.8") h
- Mounting: N Female Connector
- Operating Temperatures: -40°C to +85°C
- Weight: 270 g (0.6 lbs)
- Color: Black