Friday, December 18, 2009

Increasing the Reach of Shortwave Broadcast Systems

Small-footprint Antenna System with Unlimited Flexibility
from Thomson Radio Broadcast

Shortwave broadcast systems can reach millions of people anywhere, anytime from a single transmission site. The possibilities are theoretically unlimited. On the other hand, shortwave infrastructure is a notorious power consumer and stations require a lot of land to accommodate adequate antenna systems. Thomson’s newest rotatable curtain antenna helps broadcasters with limited space and budget to make important power savings while increasing considerably their coverage flexibility. The Thomson HP-RCA 2/2 (High
Performance Rotatable Curtain Antenna) is a highly interesting alternative system solution for broadband fixed curtain antenna configurations.

HP-RCA 2/2 services similar coverage areas as the classical LPD (Log Periodic Dipole Antenna) with up to 45% higher efficiency of the radiated power into a defined target area. Additional comparative figures of merit include

􀂄 Higher gain (up to 19 dBi, or 3 to 6 dB more than typical LPD)
􀂄 Higher front-to-back ratio (6 to 10 dB more than typical LPD)
􀂄 Better power capability (up to 500 kW, as compared to the LPD with an absolute maximum of only 250 kW)

In addition, the HP-RCA 2/2 has a better overall efficiency, requires less land, is easier to maintain and affords better reliability with regard to storms and electrostatic effects. The footprint of this powerful and highly flexible system is surprisingly small. With dimensions
of 51m x 51m, the foundation surface needs less than 12m x 12m. The covered area has a radius of approximately 50m.

With an overall weight of 80t, the antenna has a maximum survival wind speed of 240 km and a maximum operational wind speed of 120 km. It takes less than 3 minutes for a 180° rotation. Based on a rigid array and a tubular shaft, the HP-RCA 2/2 is a back-to-back arrangement of a low band and a high band curtain antenna equipped with a reflector screen. The 2/2 configuration gives a good radiation pattern performance with moderate structural effort.

Whereas the classical HR 2/2 curtain antenna solution is based on a fix structure with phasing system limited to less than 20° azimuthal slewing with considerable sidelobes, the new rotatable structure with a central shaft has 360° azimuthal performance radiation patterns without sidelobes.
from Thomson Radio Broadcast

Shortwave broadcast systems can reach millions of people anywhere, anytime from a single transmission site. The possibilities are theoretically unlimited. On the other hand, shortwave infrastructure is a notorious power consumer and stations require a lot of land to accommodate adequate antenna systems. Thomson’s newest rotatable curtain antenna helps broadcasters with limited space and budget to make important power savings while increasing considerably their coverage flexibility. The Thomson HP-RCA 2/2 (High
Performance Rotatable Curtain Antenna) is a highly interesting alternative system solution for broadband fixed curtain antenna configurations.

HP-RCA 2/2 services similar coverage areas as the classical LPD (Log Periodic Dipole Antenna) with up to 45% higher efficiency of the radiated power into a defined target area. Additional comparative figures of merit include

􀂄 Higher gain (up to 19 dBi, or 3 to 6 dB more than typical LPD)
􀂄 Higher front-to-back ratio (6 to 10 dB more than typical LPD)
􀂄 Better power capability (up to 500 kW, as compared to the LPD with an absolute maximum of only 250 kW)

In addition, the HP-RCA 2/2 has a better overall efficiency, requires less land, is easier to maintain and affords better reliability with regard to storms and electrostatic effects. The footprint of this powerful and highly flexible system is surprisingly small. With dimensions
of 51m x 51m, the foundation surface needs less than 12m x 12m. The covered area has a radius of approximately 50m.

With an overall weight of 80t, the antenna has a maximum survival wind speed of 240 km and a maximum operational wind speed of 120 km. It takes less than 3 minutes for a 180° rotation. Based on a rigid array and a tubular shaft, the HP-RCA 2/2 is a back-to-back arrangement of a low band and a high band curtain antenna equipped with a reflector screen. The 2/2 configuration gives a good radiation pattern performance with moderate structural effort.

Whereas the classical HR 2/2 curtain antenna solution is based on a fix structure with phasing system limited to less than 20° azimuthal slewing with considerable sidelobes, the new rotatable structure with a central shaft has 360° azimuthal performance radiation patterns without sidelobes.
(NASB Dec 09/Dan Elyea)