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Interference-Reducing Receiving Antennas for Shortwave Broadcasts.

PB88188180

Publication Date	1987
Personal Author	Villard, O. G.; Harker, K. J.; Hagn, G. H.
Page Count	162
Abstract	To help shortwave listeners combat interference, several simple, compact, and portable antennas were developed and their performance tested. The two preferred designs are called the horizontal loop antenna (HLA) and the twin loop antenna (TLA). The HLA is particularly easy to construct, requiring only metal foil and sheet plastic. It is exceptionally sensitive and may find use for that reason alone. An unusual characteristic is the ability simultaneously to reject a number of ground-wave signals independent of their direction of arrival. The TLA is somewhat more complicated to build, but it has the ability--unusual in a small structure--of reducing a good fraction of the vertical-plane multipath components of a given sky-wave signal. This results in a null of exceptional depth and stability (in the order of 20 dB on the average), which, in a suitable location, greatly improves direction-finding accuracy in comparison with a loop. It is found that the interference-reducing characteristics of the new antennas are reasonably well preserved indoors (although direction of arrival is unreliable), provided only that the antennas can be moved about so as to take advantage of favorable locations. In a typical room, some positions are worse for the antennas than outdoors, but in others superior interference rejection is observed.
Keywords	Directional antennas Loop antennas Electromagnetic interference Design Horizontal loop antennas Twin loop antennas Short wave radio transmission
Source Agency	Single Entry
NTIS Subject Category	49A - Antennas 45B - Radio & Television Equipment
Corporate Authors	SRI International, Menlo Park, CA.; Voice of America, Washington, DC.
Supplemental Notes	Sponsored by Voice of America, Washington, DC.
Document Type	Technical Report
Title Note	Final rept. Jan 86-Nov 86,
NTIS Issue Number	198815

Interference-Reducing Receiving Antennas for Shortwave Broadcasts.

Interference-Reducing Receiving Antennas for Shortwave Broadcasts.
PB88188180

Publication Date	1987
Personal Author	Villard, O. G.; Harker, K. J.; Hagn, G. H.
Page Count	162
Abstract	To help shortwave listeners combat interference, several simple, compact, and portable antennas were developed and their performance tested. The two preferred designs are called the horizontal loop antenna (HLA) and the twin loop antenna (TLA). The HLA is particularly easy to construct, requiring only metal foil and sheet plastic. It is exceptionally sensitive and may find use for that reason alone. An unusual characteristic is the ability simultaneously to reject a number of ground-wave signals independent of their direction of arrival. The TLA is somewhat more complicated to build, but it has the ability--unusual in a small structure--of reducing a good fraction of the vertical-plane multipath components of a given sky-wave signal. This results in a null of exceptional depth and stability (in the order of 20 dB on the average), which, in a suitable location, greatly improves direction-finding accuracy in comparison with a loop. It is found that the interference-reducing characteristics of the new antennas are reasonably well preserved indoors (although direction of arrival is unreliable), provided only that the antennas can be moved about so as to take advantage of favorable locations. In a typical room, some positions are worse for the antennas than outdoors, but in others superior interference rejection is observed.
Keywords	Directional antennas Loop antennas Electromagnetic interference Design Horizontal loop antennas Twin loop antennas Short wave radio transmission
Source Agency	Single Entry
NTIS Subject Category	49A - Antennas 45B - Radio & Television Equipment
Corporate Authors	SRI International, Menlo Park, CA.; Voice of America, Washington, DC.
Supplemental Notes	Sponsored by Voice of America, Washington, DC.
Document Type	Technical Report
Title Note	Final rept. Jan 86-Nov 86,
NTIS Issue Number	198815