Hi Brian, just something for you to think about. I faced the same problem in my lab when starting out testing at 200 v/m. We have since pushed this quite a bit higher and implemented a few things to get these higher levels:
First, it's relatively easy to make up cable losses at low signal levels, and good shielded cables are easy to find. However, I had a cable run of about 20 feet to get to the antenna and through the room wall. I found the bulkheads and even the cable would get warm during testing. Also there were several notches in the drive level from the sig gen that should not really be there. So my first step was to move the high frequency amps ( 8 to 18 GHz ) inside the room. To start with I used a sucoflex cable to feed the signal in to the rack we had these in. That works well, but it''s ungainly. So I bought an optical GP-IB link and moved both the signal source and the power meter into the chamber too. All this resides in a low height rack on LARGE wheels, the TWT's are very heavy. I used a short length of Flexible Waveguide to hook up the horn, it's long enough to change polarity. We are in the process of doing this with the 1 to 8 GHz Amps, the cable will only be a few feet long. Using all horns for transmitting, I've not observed significant influence of the racks located behind the antenna. Sincerely, Derek Walton L F Research Kunde, Brian wrote: > > How would you rank the flexibility of the following cables? (so I an > get a comparison) > > *CABLE TYPE (Insertion Loss per ft at 10Ghz)* > > * * > > UFB311A (.15) > > LMR 600 (.17) > > LMR 400 (.27) > > UFA210A (.27) > > Gore PhaseFlex (.27) > > RG-214 (.47) > > RG-393 (.35) > > EM40 (.36) > > The UFB cable has the best insertion loss of the bunch but it is very > expensive. LMR 400 cables are cheap but I’ve never seen any so I don’t > know if they are flexible. I have RG-214 cable and I find it ok to > work with so a comparison to RG214 would be good. I would guess that > LMR 600 is a tow rope. The UFA210A cable has similar loss compared to > LMR 400 but only half the diameter, so I guess much more flexible. > > I cannot get the Micro-Coax website Cable Wizard to work. When I get > to the part where I select a cable, I get a Server Error. So I have > not been able to see any prices for their cable assemblies. > > What other cable types/sources should I be looking at? > > Thanks to all for your help. I know this can seem like a very small > issue but I have no experience with high frequency low loss cable. A > fraction of a db can make a huge difference in our application > (radiated immunity up to 6Ghz) so I’m really dancing a line between > insertion loss vs flexibility. > > The other Brian > > ------------------------------------------------------------------------ > > *From:* [email protected] [mailto:[email protected]] *On Behalf Of > *Grace Lin > *Sent:* Wednesday, July 16, 2008 7:23 AM > *To:* [email protected] > *Subject:* Re: Low Loss Coax Cable > > Hi Brian, > > MegaPhase carries low loss cables > (http://www.megaphase.com/test06.html). Several commercial labs in the > northeast of the US use its cable. Order "EM40" for flexibility even > you don't need performance up to 40GHz. EM18 is not flexible and too > difficult to connect to instrument. > > The person who performed our NSA uses cables made by Micro-coax > (http://www.micro-coax.com/). From this link, > https://www.micro-coax.com/secure/(wk1c1ujm3fbhqjfmk2qho3fg)/MCConfigurator.aspx > > <https://www.micro-coax.com/secure/%28wk1c1ujm3fbhqjfmk2qho3fg%29/MCConfigurator.aspx>, > > click "Select Cable Type", you will find informaiton for diffierent > cable types. The diameters of 0.14" and 0.205" are flexible. I have > UFB311A (not as flexible as I like) and UFB142A (flexible) with 12" > length. > > My colleague ordered a PHASEFLEX cable from W.L.Gore > (http://www.gore.com/en_xx/products/cables/microwave/test/gore_phaseflex_microwave_test_assemblies.html). > > It is very flexible and durable. W.L.Gore provides online purchase and > can be received next day > (http://consumer.gore.com/webapp/wcs/stores/servlet/ProductDisplay?catalogId=10401&storeId=10401&productId=10854&langId=-1&parent_category_rn=10101 > > <http://consumer.gore.com/webapp/wcs/stores/servlet/ProductDisplay?catalogId=10401&storeId=10401&productId=10854&langId=-1&parent_category_rn=10101>). > > The price range for the above mentioned cables is $300-$1000. > > Regards, > > Grace > > On 7/15/08, *Kunde, Brian* <[email protected] > <mailto:[email protected]>> wrote: > > What coax cable types do you recommend for a very low loss cable up to > 6Ghz but also flexible? I need a good low loss cable to connect > between my horn antenna and the floor connection of my Heliax. The > cable only needs to be 5 or 6 feet long but flexible enough so I can > change polarization on my antenna. > > I have looked at many cable types in catalogs and on-line but you > cannot tell if it will be flexible without seeing it for real. I > ordered a cable called "Helical Super Flex". I liked the low loss > properties but it was not at all flexible, let alone super flexible. > It was barely semi-rigid in my book . > > I tried RG393/U but it is not very flexible and I prefer a lower loss > cable if possible. > > What do you all recommend? What is the best? Where can I buy it in > small quantities and possibly in custom lengths? > > Thanks to all in advance. > > The Other Brian > > _________________________ > > *LECO Corporation Notice*: This communication may contain confidential > information intended for the named recipient(s) only. If you received > this by mistake, please destroy it and notify us of the error. Thank you. > > - ---------------------------------------------------------------- > This message is from the IEEE Product Safety Engineering Society > emc-pstc discussion list. Website: http://www.ieee-pses.org/ > > To post a message to the list, send your e-mail to [email protected] > <mailto:[email protected]> > > Instructions: http://listserv.ieee.org/request/user-guide.html > > List rules: http://www.ieee-pses.org/listrules.html > > For help, send mail to the list administrators: > > Scott Douglas [email protected] <mailto:[email protected]> Mike > Cantwell [email protected] <mailto:[email protected]> > > For policy questions, send mail to: > > Jim Bacher: [email protected] <mailto:[email protected]> David Heald: > [email protected] <mailto:[email protected]> > > All emc-pstc postings are archived and searchable on the web at: > > http://www.ieeecommunities.org/emc-pstc - > ---------------------------------------------------------------- This > message is from the IEEE Product Safety Engineering Society emc-pstc > discussion list. Website: http://www.ieee-pses.org/ > > To post a message to the list, send your e-mail to [email protected] > <mailto:[email protected]> > > Instructions: http://listserv.ieee.org/request/user-guide.html > > List rules: http://www.ieee-pses.org/listrules.html > > For help, send mail to the list administrators: > > Scott Douglas [email protected] <mailto:[email protected]> Mike > Cantwell [email protected] <mailto:[email protected]> > > For policy questions, send mail to: > > Jim Bacher: [email protected] <mailto:[email protected]> David Heald: > [email protected] <mailto:[email protected]> > > All emc-pstc postings are archived and searchable on the web at: > > http://www.ieeecommunities.org/emc-pstc > > > - ---------------------------------------------------------------- > This message is from the IEEE Product Safety Engineering Society > emc-pstc discussion list. Website: http://www.ieee-pses.org/ > > To post a message to the list, send your e-mail to [email protected] > > Instructions: http://listserv.ieee.org/request/user-guide.html > > List rules: http://www.ieee-pses.org/listrules.html > > For help, send mail to the list administrators: > > Scott Douglas [email protected] Mike Cantwell [email protected] > > For policy questions, send mail to: > > Jim Bacher: [email protected] David Heald: [email protected] > > All emc-pstc postings are archived and searchable on the web at: > > http://www.ieeecommunities.org/emc-pstc > > _________________________ > > *LECO Corporation Notice*: This communication may contain confidential > information intended for the named recipient(s) only. If you received > this by mistake, please destroy it and notify us of the error. Thank > you. - > ---------------------------------------------------------------- This > message is from the IEEE Product Safety Engineering Society emc-pstc > discussion list. Website: http://www.ieee-pses.org/ > > To post a message to the list, send your e-mail to [email protected] > > Instructions: http://listserv.ieee.org/request/user-guide.html > > List rules: http://www.ieee-pses.org/listrules.html > > For help, send mail to the list administrators: > > Scott Douglas [email protected] Mike Cantwell [email protected] > > For policy questions, send mail to: > > Jim Bacher: [email protected] David Heald: [email protected] > > All emc-pstc postings are archived and searchable on the web at: > > http://www.ieeecommunities.org/emc-pstc > - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas [email protected] Mike Cantwell [email protected] For policy questions, send mail to: Jim Bacher: [email protected] David Heald: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
