60 GHz Wireless HD SDI – Bridge the Gap – Part 3

Download “Bridging the Gap without Cables ” 60 GHz Wireless HD SDI White Paper

Limited Propagation

A 60 GHz link operating at 1 KM only has an unused propagation of 2.5 KM.  The typical beam width is 4°.  When compared to a 2.4 GHz link, one can see the unused signal propagates 32 KM with a beam width of 12°.  A 2.5 GHz signal is far worse with a typical beam width of 117° with the same unused propagation of 32 KM.  Since 60 GHz transmission has a limited unused propagation distance and very tight beam width, it proves to be a more stealthy technology and is far less prone to cause or to be susceptible to interferences from other 60 GHz systems.  With a little bit of planning, multiple 60 GHz systems can operate in close proximity to each other.  As long as the transmitted signal beams are outside the 4° receiving aperture of any receiver, it is possible for many systems to operate in close proximity and even on the same rooftop or tower.

First and Last Mile

Free-space point-to-point optical links using laser light or possibly LED’s is an alternative to using 60 GHz wireless video transmission. However, free space optics are highly susceptible to stability and quality of the link is highly dependent on atmospheric factors such as snow, fog, rain, heat, and sandstorms making them unusable unless ideal conditions are assured.
60 GHz wireless video technology is ideal for applications were no copper or fiber optic cable options are available.  This millimeter wave technology is typically used for short ranges from 100 m to 5 KM due to the oxygen absorption properties mentioned above.  When we consider only the last mile, this short range is not a disadvantage as telecom and video transport is readily available for long-haul.  In most applications the first mile and last mile of the network are the most expensive.  This makes 60 GHz video and data transmission a cost-effective alternative to copper and fiber-optic cable in many applications.

Small Antennas

Zoning laws and architectural considerations often prevent the use of large antennas and sometimes there is just no room for their placement. Applications include ad hoc and permanent installations for military, newsgathering, sporting events, and building to building links.

The wide bandwidth of 60 GHz transmission supports uncompressed 1.485 Gbps HD-SDI and DVB ASI with a reach of up to 1 KM. In combination with the short wavelength of 60 GHz which permits the use of small and discrete antennas, it is an ideal bandwidth for these applications.

Polarization

The transmission of 60 GHz has polarization.  Polarization is a property of waves that can oscillate in more than one orientation.  Polarization provides added isolation to operate 60 GHz signals in close proximity.  Polarization typically operates on a Zero and 90 degree axis.  One signal can operate on a zero degree polarization while another can operate at 90 degrees providing isolated transmission of two signal channels.  Additional channel isolation can be achieved by using two different frequencies in the 60 GHz band.  This provides the building blocks for a bi-directional 60 GHz video or data link.  Note the polarization guide in the image in Figure 3 above referenced to the hockey red goal line.

Download “Bridging the Gap without Cables ” 60 GHz Wireless HD SDI White Paper