If you need assistance, please send an email to forum at 4hv dot org. To ensure your email is not marked as spam, please include the phrase "4hv help" in the subject line. You can also find assistance via IRC, at irc.shadowworld.net, room #hvcomm.
Support 4hv.org!
Donate:
4hv.org is hosted on a dedicated server. Unfortunately, this server costs and we rely on the help of site members to keep 4hv.org running. Please consider donating. We will place your name on the thanks list and you'll be helping to keep 4hv.org alive and free for everyone. Members whose names appear in red bold have donated recently. Green bold denotes those who have recently donated to keep the server carbon neutral.
Special Thanks To:
Aaron Holmes
Aaron Wheeler
Adam Horden
Alan Scrimgeour
Andre
Andrew Haynes
Anonymous000
asabase
Austin Weil
barney
Barry
Bert Hickman
Bill Kukowski
Blitzorn
Brandon Paradelas
Bruce Bowling
BubeeMike
Byong Park
Cesiumsponge
Chris F.
Chris Hooper
Corey Worthington
Derek Woodroffe
Dalus
Dan Strother
Daniel Davis
Daniel Uhrenholt
datasheetarchive
Dave Billington
Dave Marshall
David F.
Dennis Rogers
drelectrix
Dr. John Gudenas
Dr. Spark
E.TexasTesla
eastvoltresearch
Eirik Taylor
Erik Dyakov
Erlend^SE
Finn Hammer
Firebug24k
GalliumMan
Gary Peterson
George Slade
GhostNull
Gordon Mcknight
Graham Armitage
Grant
GreySoul
Henry H
IamSmooth
In memory of Leo Powning
Jacob Cash
James Howells
James Pawson
Jeff Greenfield
Jeff Thomas
Jesse Frost
Jim Mitchell
jlr134
Joe Mastroianni
John Forcina
John Oberg
John Willcutt
Jon Newcomb
klugesmith
Leslie Wright
Lutz Hoffman
Mads Barnkob
Martin King
Mats Karlsson
Matt Gibson
Matthew Guidry
mbd
Michael D'Angelo
Mikkel
mileswaldron
mister_rf
Neil Foster
Nick de Smith
Nick Soroka
nicklenorp
Nik
Norman Stanley
Patrick Coleman
Paul Brodie
Paul Jordan
Paul Montgomery
Ped
Peter Krogen
Peter Terren
PhilGood
Richard Feldman
Robert Bush
Royce Bailey
Scott Fusare
Scott Newman
smiffy
Stella
Steven Busic
Steve Conner
Steve Jones
Steve Ward
Sulaiman
Thomas Coyle
Thomas A. Wallace
Thomas W
Timo
Torch
Ulf Jonsson
vasil
Vaxian
vladi mazzilli
wastehl
Weston
William Kim
William N.
William Stehl
Wesley Venis
The aforementioned have contributed financially to the continuing triumph of 4hv.org. They are deserving of my most heartfelt thanks.
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
Ive been looking at attenuation and control of RF waves in various applications like wave guides unwanted coupling in micro electronics like iPods and laptops. But as I look more and more into this physics i find some intriguing military and civilian apparent "conflicts". Obviously a great deal of money is spent by militaries and cell phone companies to deal with radomes.
But my question is this...
In a stealth fighter the forward hemisphere is the most stealthy by design. And as seen on the "alien school bus" and YF-23 the nose is boat or shovel shaped, and of course doped with iron and similar materials. So how do the radar waves they transmit make it through the nose cone - then receive that friendly signal back !? The attenuation of the returning signal should be debilitating, yet these special phased array radars seem to work exceptionally well.
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
AN/APG-77
It has so many features though. Ive been told it can selectively jam enemy radar, without filling his screen with bogus blobs as with traditional jamming. It can jam to favor friendly aircraft while allowing the enemy to see their own aircraft undisturbed, if desired. They would quite literally die while looking at their normal screen.
Registered Member #2099
Joined: Wed Apr 29 2009, 12:22AM
Location: Los Altos, California
Posts: 1714
Long ago I had a work stint at Hughes Aircraft, Radar Systems. As a very junior designer, no expert here, in the days of AN/AWG-9.
Here's a guess at answer to question in OP. Probably applies to modern airborne radar systems. The radome shell has to be be aerodynamic, strong, and transparent to Radar frequencies. A hole in the middle of otherwise stealthy aircraft shape designed for low return cross-section.
Most of the radome area, in front view, is phased-array antenna surface. I guess that could be practically a black body at radar frequencies, since incident power is supposed to be coupled into well-terminated pipes. Have no idea what happens to power from directions not being looked at, so the signals from different antenna elements are combined out of phase.
Off topic a bit: The Malaysia Air Flight 17 crash report brought public attention to a detail I'd learned at Hughes, about antiaircraft missile warheads. Sometimes also mentioned lately in context of Israel's "Iron Dome" system.
Warheads do their job when a missile is physically missing its target, which happens in most shots. A Buk or Phoenix-size missile, in an actual high-speed collision, could be inert & still generally destroy any size aircraft. For the near-miss cases, a ring of high-explosive-driven fragments is the lethal mechanism. Fuze system needs to detect the geometry of encounter, and fire warhead at the optimum instant.
p.s. It's been noted by others that the term "near miss" is a misnomer. If I nearly climbed a mountain, that means I didn't get to the top. If I nearly missed the train, that means I boarded on time. If my shot nearly hits the target, but misses, that's a near hit. A near miss would mean it almost missed.
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
I don't know if other countries use the annular bast fragmentation warhead like the AIM-9 sidewinder family. But Klugesmith that method of laser-expanding-copper warhead solves the problem you speak of. I had not considered this.
This site is powered by e107, which is released under the GNU GPL License. All work on this site, except where otherwise noted, is licensed under a Creative Commons Attribution-ShareAlike 2.5 License. By submitting any information to this site, you agree that anything submitted will be so licensed. Please read our Disclaimer and Policies page for information on your rights and responsibilities regarding this site.
A Question About Stealth and How to Transmit and Receive Friendly Radio Waves.
