Radio frequency anechoic chamber with nonperturbing wireless signalling means
View Patent ↗An anechoic chamber ( 100 ) is provided with a system for introducing wireless communication signals into the anechoic chamber ( 100 ) for establishing wireless signaling with equipment under test ( 122 ), without interfering with signals from the equipment under test ( 122 ) that are to be measured in the anechoic chamber ( 100 ). The system comprises a low reflection cross-section cable ( 236 ) that extends through the chamber ( 100 ) to a weakly radiating small antenna ( 242, 502 ) that is positioned proximate the equipment under test ( 122 ).
1. An apparatus comprising:
a radio frequency instrument adapted to operate at a frequency;
a low reflection cross-section cable comprising:
a coaxial cable;
a first end coupled to the radio frequency instrument;
a second end; and
a plurality of cylindrical resonators through which said coaxial cable passes,
wherein each of said plurality of cylindrical resonators comprises:
a cylinder having an open first end and a second end closed by a circular wall that includes a hole through which said coaxial cable passes;
an antenna coupled to said second end of said low reflection cross-section cable.
2. The apparatus according to claim 1 wherein said antenna is sized substantially below a size required for resonance at said frequency.
3. The apparatus according to claim 1 wherein said antenna comprises a monopole antenna.
4. The apparatus according to claim 3 wherein said monopole antenna has a length that is less than ⅛ of a free space wavelength corresponding to said frequency.
5. The apparatus according to claim 1 wherein said antenna comprises a loop antenna.
6. The apparatus according to claim 1 wherein each of said plurality of cylindrical resonators further comprise a dielectric plug disposed, at least partly, in said cylinder, said dielectric plug comprising an axial bore through which said coaxial cubic passes.
7. The apparatus according to claim 6 wherein said dielectric plug extends out of said cylinder.
8. The apparatus according to claim 1 further comprising an anechoic chamber wherein said radio frequency instrument is disposed outside said anechoic chamber, said antenna is disposed inside said anechoic chamber and said low reflection cross-section cable is disposed, at least partly, in said anechoic chamber.
9. An apparatus comprising:
an anechoic chamber for making measurements at, at least one frequency;
a rotatable test stand for supporting a piece of equipment under test, the rotatable test stand disposed in said anechoic chamber and having a rotary radio frequency coupling;
an antenna disposed in said anechoic chamber and mounted to said rotatable test stand, wherein said antenna is sized substantially below a size required for resonance at said at least one frequency; and
a low reflection cross-section cable comprising a first end coupled to said antenna and a second end.
10. The apparatus according to claim 9 wherein:
said rotatable test stand comprises an axis and an end; and
said rotary radio frequency coupling is disposal on said axis proximate said end.