wmartin@STL-06SIMA.ARMY.MIL (Will Martin) (08/21/90)
From: Will Martin <wmartin@STL-06SIMA.ARMY.MIL> Can anti-radiation missiles, which usually are used against radars operating in the UHF or microwave range, be used against targets emitting lower frequencies, like HF radio? Could such a missile be used to home in on the antenna of a transmitter being used to jam shortwave broadcast reception, for example? [After the first missile takes out the antenna, could a second one then home in on the transmitter itself, assuming it is still operating briefly before the operators shut it down, or the internal protection circuits notice that the antenna load is gone, and shut the transmitter down in self-protection from burnout?] Or would the propagation modes and general lesser directivity of lower radio frequencies keep the homing functions from operating correctly? If it does work, can the radio-reception frequency span of the missile's homing circuitry be "dialled in" in the field, or is this something that has to be factory-set? Regards, Will wmartin@st-louis-emh2.army.mil OR wmartin@stl-06sima.army.mil *** "Fire and Forget" means never having to say you're sorry... ***
nak%archie@att.att.com (Neil A Kirby) (08/23/90)
From: nak%archie@att.att.com (Neil A Kirby) In article <1990Aug21.024249.220@cbnews.att.com> Will Martin <wmartin@STL-06SIMA.ARMY.MIL> writes: [stuff deleted] >From: Will Martin <wmartin@STL-06SIMA.ARMY.MIL> >Can anti-radiation missiles, which usually are used against radars operating >in the UHF or microwave range, be used against targets emitting lower >frequencies, like HF radio? Could such a missile be used to home in on the >antenna of a transmitter being used to jam shortwave broadcast reception, >for example? [After the first missile takes out the antenna, could a second >one then home in on the transmitter itself, assuming it is still operating >briefly before the operators shut it down, or the internal protection >circuits notice that the antenna load is gone, and shut the transmitter >down in self-protection from burnout?] I have problems with the "takes out the transmitter" part. The only thing that the missle can really see (electromagnetically) is the antenna. The transmitter is some unknown length of coax away from the antenna. Once the antenna is gone, the shredded coax will likely make a damn poor antenna: impossibly hard to home in on [pause for comic relief: I have visions of very expensive, highly sensitive missiles blasting apart a quarter mile of coax cable 50 feet at a time], and very hard on the final output amplifier stages of the tranmitter. The tranmitter is likely, as you suggest, to shut itself down. Some of these things are capable of taking baby lightening strikes and staying on the air. Take a look at any radio or TV broadcast tower site some time. The buildings that house the transmitter are some distance away from the tower. It's not healthy for them to be in the vicinity of HARM missile mayhem, but they aren't directly threatened. Neil Kirby ...att!archie!nak
lewis@saint (Keith Lewis) (08/28/90)
From: lewis@saint (Keith Lewis) In article <1990Aug21.024249.220@cbnews.att.com> Will Martin <wmartin@STL-06SIMA.ARMY.MIL> writes: >Can anti-radiation missiles, which usually are used against radars operating >in the UHF or microwave range, be used against targets emitting lower >frequencies, like HF radio? Could such a missile be used to home in on the >antenna of a transmitter being used to jam shortwave broadcast reception, >for example? In order to home in on a transmitting antenna, the missile needs a recieving antenna (or three) of its own. The size of a given design of antenna is some fraction (preferably 1) of the wavelength (inversly proportional to the frequency) of the broadcast you want to home in on. Radar is measured in centimeters. HF is measured in meters. So for *Optimal* design, you would make the antennae a number of meters in size. Whether you really need this optimization I can't say. There may be other designs that are effective, or maybe the radar antennae will work *well enough* to take out a powerful transmitting antenna. -- Keith Lewis Saddam Hussein says he would pull out of Kuwait, but Islamic law prohibits him. "That would be Kuwaitis interruptus!"