Electro-Metrics now makes such a device covering the entire 30 - 1000 MHz range. They use ordinary telescoping elements, but use a motor-driven non-conductive device to gradually shorten the elements as you tune up through a band.
---------- >From: "Patrick, Al" <[email protected]> >To: "'Price, Ed'" <[email protected]>, "'[email protected]'" <[email protected]>, [email protected] >Subject: RE: Looking for tunable dipole antenna. >Date: Wed, Jan 19, 2000, 12:28 PM > > > Joe, and friends > > > What I think you're looking for was a military product made by Collins Radio > Co. which is now Rockwell. > > The antenna was a pair of silver plated steel tapes (much like a common > measurement tape) marked in Cementers and motor driven. The control unit > would adjust the length of the silver tapes to a preset configuration. It > had about 12 channels and came in different frequency ranges. The lowest > being 2 to 30 mHz. That is about all I remember, but it is an interesting > idea and would allow the automation of site attenuation and may be better > than using biconicals. > > Al Patrick, Sr. EMC Engineer - Scientific-Atlanta Inc. 5030 EMC Lab. > [email protected] > > -----Original Message----- > From: Price, Ed [mailto:[email protected]] > Sent: Wednesday, January 19, 2000 1:27 PM > To: '[email protected]'; [email protected] > Subject: RE: Looking for tunable dipole antenna. > > > > > > >> -----Original Message----- >> From: [email protected] [SMTP:[email protected]] >> Sent: Wednesday, January 19, 2000 5:53 AM >> To: [email protected] >> Subject: Looking for tunable dipole antenna. >> >> >> Does anybody have any idea on where I can purchase a set of dipole >> antennas >> that have tunable baluns? I need them for performing pre-compliance >> antenna >> gain tests on some of the antennas that are used on the various Racal >> handheld radios. The frequency range I am interested in is the 30 MHz to >> 1 >> GHz frequency range. I am interested in either used or new antennas. I >> had >> a set of them about 20 years ago but don't remember whether they were home >> made or something we purchased from some manufacturer. If you have any >> ideas for a source please let me know. >> >> Thanks, >> Joe O'Banion >> >> > Joe: > > First, I wonder why you prefer a tunable balun? But assuming you really do > want that, it makes the selection rather narrow. > > The only tunable balun I have ever seen on a test antenna was the old > Stoddart 91598-2 dipole, which operated between 375 MHz and 1000 MHz. Not > only did you have to adjust the length of the dipole arms for each > frequency, you also had to adjust the position of a sliding short on the > twin-tube "boom". (I'm not too certain about this, but the twin tubes and > the sliding short may have been what's called a "J" match.) > > However, the other associated Stoddart dipoles, as well as Empire's, > Eaton's, AH Systems' and Schwarzbeck's dipoles all used fixed baluns. The > 91598-2 is so old that finding one would very difficult; accessories like > antennas often go astray from the equipment (the NM-52A EMI Meter) when the > equipment is scrapped. > > Regards, > > Ed > > > :-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-) > Ed Price > [email protected] > Electromagnetic Compatibility Lab > Cubic Defense Systems > San Diego, CA. USA > 858-505-2780 (Voice) > 858-505-1583 (Fax) > Military & Avionics EMC Services Is Our Specialty > Shake-Bake-Shock - Metrology - Reliability Analysis > :-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-):-) > > --------- > This message is coming from the emc-pstc discussion list. > To cancel your subscription, send mail to [email protected] > with the single line: "unsubscribe emc-pstc" (without the > quotes). For help, send mail to [email protected], > [email protected], [email protected], or > [email protected] (the list administrators). > > > > *** > > --------- > This message is coming from the emc-pstc discussion list. > To cancel your subscription, send mail to [email protected] > with the single line: "unsubscribe emc-pstc" (without the > quotes). For help, send mail to [email protected], > [email protected], [email protected], or > [email protected] (the list administrators). > > --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to [email protected] with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to [email protected], [email protected], [email protected], or [email protected] (the list administrators).
