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Re: Circular polarization antenna question
dave powis
Septum feed is going to require some smart machining at 36GHz - the diameter of the waveguide is around 0.71 lambda - haven't done the sums for 36G, but at 10G thats just about 20mm. You'll also have to check out what the matching is to whatever reflector you're using (I'm assuming that this will be at the focus of a small dish?) CWST (circular waveguide septum transformer) and RWST (rectangular WST) feeds are optimum for f/d of around 0.4, and even then benefit from some cavity rings a la VE4MA (see W1GHZ work) or Chapparal (see W1GHZ or recent practical work by DL4MEA). To adapt to other dish f/d ratios flared horns work well on the front of the feed.
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You would probably benefit by looking at W1GHZ's latest work, published at Microwave Update in PA 2 weeks ago - this will be on his website, or on the MUD2007 site. Cheers, Dave ----- Original Message ----
From: J Forster <jfor@...> To: hp_agilent_equipment@... Sent: Sunday, 4 November, 2007 2:12:27 AM Subject: Re: [hp_agilent_equipment] Circular polarization antenna question Another lead from a local ham: For the guy looking for the circular pol horn info Try the W1GHZ on line microwave antenna book . org/antbook/ contents. htm His best bet is the Septum feed . org/antbook/ conf/SEPTUM. pdf I really don't want to register to join the Yahoo group so I'll be happy reading only. Best, -John lothar baier wrote: i dont have any of those books on hand, i never had much interest in antennas so i got a bunch of other books and periodicals but nothing on antenna stuff J Forster <jfor@...> wrote: Have you looked at some of the old standard books like Kraus or the Rad Lab series? I'd at least start there. Then perhaps the IEEE Antenna & Propagation (or whatever it is actually called) The web is fine for some things, but is not great on fundamental engineering. Also, Google has an academic research function. That might give you a lead. Best, -John microwaveengineer19 68 wrote: Ok guys this is not directly related to agilent t+m but im banging my head on the wall with this ! Im looking for material on how to design and build a turnstile polarization converter, i googled up and down but cant find anything usefull , not even in the books i have. The problem i have requires me to design and build a 36GHz circular polarized horn antenna, the antenna needs to have two ports one for right and the other one for left turn polarization . any help would be appreciated ____________ _________ _________ _________ _________ __ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around . yahoo.com Yahoo! Groups Links <!-- #ygrp-mkp{ border:1px solid #d8d8d8;font-family:Arial;margin:14px 0px;padding:0px 14px;} #ygrp-mkp hr{ border:1px solid #d8d8d8;} #ygrp-mkp #hd{ color:#628c2a;font-size:85%;font-weight:bold;line-height:122%;margin:10px 0px;} #ygrp-mkp #ads{ margin-bottom:10px;} #ygrp-mkp .ad{ padding:0 0;} #ygrp-mkp .ad a{ color:#0000ff;text-decoration:none;} --> <!-- #ygrp-sponsor #ygrp-lc{ font-family:Arial;} #ygrp-sponsor #ygrp-lc #hd{ margin:10px 0px;font-weight:bold;font-size:78%;line-height:122%;} #ygrp-sponsor #ygrp-lc .ad{ margin-bottom:10px;padding:0 0;} --> <!-- #ygrp-mlmsg {font-size:13px;font-family:arial, helvetica, clean, sans-serif;} #ygrp-mlmsg table {font-size:inherit;font:100%;} #ygrp-mlmsg select, input, textarea {font:99% arial, helvetica, clean, sans-serif;} #ygrp-mlmsg pre, code {font:115% monospace;} #ygrp-mlmsg * {line-height:1.22em;} #ygrp-text{ font-family:Georgia; } #ygrp-text p{ margin:0 0 1em 0;} #ygrp-tpmsgs{ font-family:Arial; clear:both;} #ygrp-vitnav{ padding-top:10px;font-family:Verdana;font-size:77%;margin:0;} #ygrp-vitnav a{ padding:0 1px;} #ygrp-actbar{ clear:both;margin:25px 0;white-space:nowrap;color:#666;text-align:right;} #ygrp-actbar .left{ float:left;white-space:nowrap;} .bld{font-weight:bold;} #ygrp-grft{ font-family:Verdana;font-size:77%;padding:15px 0;} #ygrp-ft{ font-family:verdana;font-size:77%;border-top:1px solid #666; padding:5px 0; } #ygrp-mlmsg #logo{ padding-bottom:10px;} #ygrp-vital{ background-color:#e0ecee;margin-bottom:20px;padding:2px 0 8px 8px;} #ygrp-vital #vithd{ font-size:77%;font-family:Verdana;font-weight:bold;color:#333;text-transform:uppercase;} #ygrp-vital ul{ padding:0;margin:2px 0;} #ygrp-vital ul li{ list-style-type:none;clear:both;border:1px solid #e0ecee; } #ygrp-vital ul li .ct{ font-weight:bold;color:#ff7900;float:right;width:2em;text-align:right;padding-right:.5em;} #ygrp-vital ul li .cat{ font-weight:bold;} #ygrp-vital a{ text-decoration:none;} #ygrp-vital a:hover{ text-decoration:underline;} #ygrp-sponsor #hd{ color:#999;font-size:77%;} #ygrp-sponsor #ov{ padding:6px 13px;background-color:#e0ecee;margin-bottom:20px;} #ygrp-sponsor #ov ul{ padding:0 0 0 8px;margin:0;} #ygrp-sponsor #ov li{ list-style-type:square;padding:6px 0;font-size:77%;} #ygrp-sponsor #ov li a{ text-decoration:none;font-size:130%;} #ygrp-sponsor #nc{ background-color:#eee;margin-bottom:20px;padding:0 8px;} #ygrp-sponsor .ad{ padding:8px 0;} #ygrp-sponsor .ad #hd1{ font-family:Arial;font-weight:bold;color:#628c2a;font-size:100%;line-height:122%;} #ygrp-sponsor .ad a{ text-decoration:none;} #ygrp-sponsor .ad a:hover{ text-decoration:underline;} #ygrp-sponsor .ad p{ margin:0;} o{font-size:0;} .MsoNormal{ margin:0 0 0 0;} #ygrp-text tt{ font-size:120%;} blockquote{margin:0 0 0 4px;} .replbq{margin:4;} --> |
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