AMiBA PROJECT WEEKLY MEETING MINUTES
Date: 31/August/2000
Attendants: B. Martin, H. Wang + 3 students, M. Kesteven, W. Wilson, M.T. Chen, H.C. Lu, Eugene Hwang , P. Shaw
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Issues |
Description |
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Output |
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MMIC- W- Band InP HEMT LNA |
2.Huei say in the last week, they have updated the design goal for InP design , and also emailed it over to everyone to review. He hope it would be not much problem. 3.Regarding the JPL's stuff, Huei talked to Todd in yesterday. Todd said he sent a formal request to the JPL's headquarter to request to loan us two modules of InP, and he will keep us informed the result. 4.As for the 0.1um GaAs HEMT design work is still ongoing, the first design review will be made in mid of Sept., and finish the design in mid of Oct, so far everything is on schedule. 5.As for the Gilbert Cells Multiplier, Paul Roberts and Warwick think the GaAs HEMT is worse than the HBT due to high noise and conversion loss. Huei said they has completed 80% of the design work with the GaAs HEMT for Gilbert Cells Multiplier, he will continue finishing that work. But he will send an email to Paul Robers for further discussion about this question. 6.Regarding the required heat dispersion data of the RF amplifiers, Huei already forwarded Todd's e-mail to Mintang. That total heat is is only a few mw, less than 10 mw, Huei think. 7.H. Wang said there is no further progress report from TRW for the export license of InP HEMT, so we need to keep waiting for a while. However, Huei confirmed with Todd, he said we still can suitable for putting our design on JPL's mask around Nov for InP HEMT. 8. Waveguide filter - Mal thinks it is the tough one, but from a system point of view, these numbers are reasonable. So Huei will pass it to Prof. Wu, let him to check if he can follow the design goals to build a module.(Huei already sent that design goal data to Prof. Wu, but got no response from him yet.) 9. We received a formal quotation from NRAO for 4 units of 82~106 GHz amplifiers, delivery for the first two units is on or before Nov. 31, 2000, delivery for the remaining 2 units is on or before July 31, 2001. Now, await Fred's approval for that ordering. 10. Mal said he got the first chip back from TRW for InP LNA, at present they try very hard to get them into the amplifier test, as soon as they have some number on that test. He will let us know. Warwick said the dead line for that work is by the end of Nov. So Mal is pushing very hard on that. |
H. Wang ¡@ H. Wang ¡@ H. Wang ¡@ H. Wang ¡@ H. Wang ¡@ ¡@ H. Wang ¡@ H. Wang ¡@ H. Wang ¡@ ¡@ P. Shaw ¡@ ¡@ M. Sinclair |
ASAP ¡@ DONE ¡@ Ongoing ¡@ Ongoing ¡@ ASAP ¡@ ¡@ DONE ¡@ Ongoing ¡@ Ongoing ¡@ ¡@ Next week ¡@ ¡@ ongoing |
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Lag correlator hybrid |
1.For the 17 lag correlator, Jeff said the Gramic is till working on that, he don't expect anything for several more weeks. 2.For the Gilbert Cell Multiplier spec, H. Wang reminds J. Peterson to generate a specification to help S.S. Shen and his student to design that amplifier. He also asks W. Wilson to give his comment on that spec. He hopes to read and to discuss their inputs in the next week. 3.Huei said that according the Fushimi's paper; the diode mixer has a worse loss than the conventional mixer at RF &LO powers input. He will email that paper to Jeff to review. Jeff agreed to compare it with what he has made in his lab. Jeff will also email everyone the responsive result in lab. 4.Jeff said that the email he did send around , what he realize that the signal level arriving both Gilbert Cell and mixers are quiet small, in few microwatts (-25dBm). The division of tree structure to be made with the resistor, which make that structure much smaller. Warwick says the resistor is much lower in the tree structure, and it certainly is the advantage to achieve that bandwidth as we talk about. The structure will be bigger than the structure of Gilbert Cell itself, probably twice as big. Jeff will keep on thinking about an idea of merit. He may try it, perhaps to build one. 5. Jeff said the progress of the Gramic today about switching that they are thinking for us for the tree structure and the resistance divider. This makes the two technology re-testing as different as possible, and we learn more as we do that way, so his suggestion is that we do that by the tree structure with mixer from that MMICs, and then we go continuously with the delay line lag correlator. Warwick says he have not decided definitely on that structure. But he will come out some simulation with other work they do. Jeff said he would like better for what he try, so he probably will go ahead that direction. Warwick agrees with Jeff to choose that mixer tree structure. 6. Warwick said he is still waiting for the HBT Gilbert Cell multipliers coming back, and last week we heard TRW will deliver them in early September. Presently, he is working on the 4 GHz lag correlator by using the commercial Gilbert Cell multipliers, he should have something comes out in a couple of weeks, he hopes. 7. Layout of the circuit board - Jeff is thinking about how to layout the circuit board to accommodate the correlator self, LN DC multipliers, converter and custom chips. He thinks those item probably take us a good realistic, and may be a square inch or two? if we are lucky. Warwick is also thinking a little bit about how to put them together, he thinks we need more information to figure out a lot of matters. Jeff suspects Taida is capable to built the hybrid chips with CMOS technology. 8. Because T.D. Chiueh's student - Ray Wei is travelling abroad and Steven Shen is busy with SMA in Taichung, we got no report from them. Paul will talk with Steven to solve this problem. |
J. Peterson J. Peterson ¡@ J. Peterson ¡@ ¡@ ¡@ ¡@ ¡@ J. Peterson ¡@ J.Peterson ¡@ ¡@ ¡@ ¡@ W. Wilson ¡@ ¡@ ¡@ ¡@ T.D. Chiueh ¡@ P. Shaw |
Ongoing ASAP ¡@ ASAP ¡@ ¡@ ¡@ ¡@ ¡@ ASAP ¡@ ASAP ¡@ ¡@ ¡@ ¡@ ongoing ¡@ ¡@ ¡@ ¡@ ¡@ ¡@ ASAP |
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Receiver |
1. Mintang decides to use the Daikin cooler, with a student's assistance, the preparation work for purchasing is starting now. 2.As to the OMT, there are two available sources - NRAO & Atlantic, Mintang has been contacting both of them, once he got price information he will let Mal know. 3.There are nothing new on the progress in the past week, Mintang said. Currently he is busy with the SMA work in Taichung. He will input something in the next week. |
M.T. Chen M.T. Chen ¡@ M.T. Chen |
ASAP ongoing ¡@ Next week |
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LO/IF |
Technology saying they need one year for delivering those components. Warwick will provide the other alternative informatiom to Eugene. Eugene also got some price from New Port, he intend to use their optical couplers and filters for the prototype module, there are small items, unit price are only several hundred USDs. So far, he got most of the prices of the instruments we need in the Lab. 2.Leo received the equalizer information from George, and he is trying to use this calculation to run some circuits. Eugene said we have a problem with the delivery time for the photo detector we are planning to use in NRAO's Lab by September. The vender just informed us the delivery time is 12 weeks (end of Nov). So in this case, it is not possible to make the test for that component while they are visiting NRAO by September. Bob suggests they should not postpone their traveling schedule to NRAO, because of the main point is to acquire more design information and see what they got there, and work on the detail design. Probably shortening the trip to one week instead of two. So he thing that would be still good to go at that time even without that component. Eugene will send an email to inform the above situation and see what he is thinking. |
H.C. Lu W. Wilson ¡@ ¡@ ¡@ ¡@ ¡@ ¡@ Y.J. Hwang |
Ongoing ASAP ¡@ ¡@ ¡@ ¡@ ¡@ ¡@ ASAP |
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30 cm antenna |
Michael has discussed with G.James about the mutual coupling problem between small antennas. They are going to find a single model, and to calculate on it. Graham will carry out some preliminary calculation to see if the coupling requirements have a chance of being met. Result to be available by 30 August. ( Michael will contact James to see the calculation result.) |
M. Kesteven |
ASAP |
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Platform/mount |
Bob said for the prototype system, we should build two individual mounts to test entire system as a 2 interferometer. These two mounts should be optimized for the receiver + 1.2m aperture dish sizes. We can fully test the concept the concept of the hexapod mount, the shadowing adjustment features, polarization rotation, tracking, etc. To test the close packed, 0.3m aperture problems, he proposed that we do this separately by mounting the two receivers together on one of these (modified) mounts. We could then study the cross talk and background fringe problems for our particular optics and mount configuration. This study requires a proper background screen behind the instrument and a good site. Michael thinks to build a platform together with the shield would be much cheaper than to build the individual mounts and delay line system. He thinks we should to build the prototype as soon as we can. Warwick said that he is worry about the complication having the delay line system on the individual mounts, it will be difficult to achieve that in time by mid of next year. So he suggest to put two receivers together on the mount (a small mount), as we need to do for the CMB experiment, and we don't need to worry about the delay system and we can do experiment on coupling. Tsihong comments on the size of 1.2m dishes - he did some simulation on the SZ map, he found for large dish (1.5 ~2m) is not as good as the small dished in term of the image quality, he also assumes a close packed configuration for the spec. He also make comparison with CBI, CBI has lower resolution because they have lower frequency. In terms of CBI, for 1.5m dish we only catch the core of the cluster, and for large dish, it just completely missing. He will continue their run to find out the optimal size for dish. Tsihone thinks he could do some contribution on the base line to see if we need to go as large as 25m. Right now he is only trying the most convenient configuration - the close packed one. The primary goal for SZ experiment is to do the clusters survey, and we want to capture all the available clusters. So give the system temperature, he really want to have a configuration of signal pump out instead of contaminate by noise. The internal structure of the clusters is going to be more a secondary goal. He agreed we could make the decision on the mount a year after we built up a prototype and found out whether the ground shied is really improved significantly or not. |
J. Peterson ¡@ B. Martin ¡@ M. Kesteven ¡@ ¡@ |
ASAP ¡@ ¡@ ¡@ DONE ¡@ ¡@ |
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Agreement |
Paul confirms he received the originals of the Agreement between ASIAA and ATNF, now await Fred back to sign it. |
P. Shaw |
Next week |
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Specification & Project book |
1.Michael says he is processing on drafting specs for AMiBA, after circulating it here he will send a copy to Bob to look at. (Paul already emailed that draft to everyone to look at.) People could send comments to Bob and Michael for any particular area, and we can start editing and updating on them. We should work out a book of specification for other stuff, and currently Michael is working on that. 2.We need someone to take care of the master filing for the dynamic project book, and let people know what we are doing and a lot open issues and provide an easy access to fill in their comments, probably through web site. Bob will talk with Paul to find out a solution after meeting. 3.Warwick reminds we need quickly to complete the specification for prototype which we are going to build up by the mid of next year. Bob is working on that, he will try to out line some of them by the next week also. |
M. Kesteven ¡@ ¡@ B. Martin ¡@ ¡@ B. Martin |
ASAP ¡@ ¡@ ASAP ¡@ ¡@ 7 Sep. |
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Teleconference links |
Bob said he is trying to fix the line, but for the time been we should leave that as usual for a while, until it was confirmed for a long term basis how many connections would be in line. So Bob will keep us informed the connection line accordingly. |
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Travelling |
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Next Meeting |
8:30pm EDT, 8:30am Taiwan, 10:30 Australia, 5:30pm Tucson/Thursday/7 September 2000 |
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