[amsat-bb] Re: Question adding RHCP to Cheap Yagi

[Curt Nixon <cptcurt@xxxxxxxxx>]

Thanks Howard...Thin I've got it.  Its going up this afternoon.  Boom is 
drilled, elements made.  Just mounting them now and then the harness..

Curt






Howard Long wrote:
> Hi Curt
>
> There are several ways to skin the same cat.
>
> Although they are fed in phase, they are orthogonally mounted and with their
> spatial separation a 90 degree phase delay is created, thus creating CP.
>
> If the elements are still orthogonal but are at the same location along the
> boom, then the delay would need to be inserted electrically, with an
> electrical 1/4 wave section of 50 ohm coax. Some CP antennas use a
> combination of both spatial and electrical phase difference.
>
> To switch RHCP to LHCP can be achived by any of the following three means:
>
> O Insert an additional 180 degree electrical delay between one arm of the
> power splitter and the antenna, with an electrical lambda/2 50 ohm coax
> section;
>
> O Physically move one set of elements 180 degrees forward or behind;
>
> O Turn one of the driven elements 180 degrees so the loop is on the other
> side of the antenna, but maintain the same electrical connections.
>
> This may (of may not!) help... http://www.g6lvb.com/remotepolarization.htm
>
> It takes a bit of lateral thinking, but once you've figured it out it's a
> bit like learning to ride a bike in that you don't forget, although in later
> years I find one may become a little wobbly.
>
> 73, Howard G6LVB
>
>
> -----Original Message-----
> From: Curt Nixon [mailto:cptcurt@flash.net] 
> Sent: 02 January 2009 16:50
> To: Howard Long
> Cc: 'AMSAT-BB'
> Subject: Re: [amsat-bb] Question adding RHCP to Cheap Yagi
>
> Hi Howard:
>
> Thanks..I've looked at alot of your info on-line--especially the sub-500GBP
> AO-40 setup. 
>
> I guess I still don't get it..if I just feed them in-phase with both
> connections same polarity, what controls RH v. LH?
>
> Or is it RH if the front half loop is to the right and LH if the front
> half-loop is to the left?
>
> Thanks
>
> Curt
>
> Too cold to not get it right on the first try!! 
>
>
>
> Howard Long wrote:
>   
>> Hi Curt.
>>
>> Either way will work.
>>
>> http://www.g6lvb.com/AO-40%2070cm%20uplink%20antenna.htm
>>
>> I have had superb success with mine, in fact during the days of AO-40 
>> I worked the world with it as an uplink antenna with 50W.
>>
>> http://www.g6lvb.com/3A2%20ops.htm
>> http://www.g6lvb.com/dayton_demo_2002.htm
>>
>> 73, Howard G6LVB
>>
>> -----Original Message-----
>> From: amsat-bb-bounces@amsat.org [mailto:amsat-bb-bounces@amsat.org] 
>> On Behalf Of Curt Nixon
>> Sent: 02 January 2009 15:19
>> To: AMSAT-BB
>> Subject: [amsat-bb] Question adding RHCP to Cheap Yagi
>>
>> Good Morning All:
>>
>> I've been using a 10el version of Kent Britain's Cheap yagi for my 
>> 70cm downlink antenna.  It suffers from deep fades so I am going to 
>> add the second yagi with physical offset to get to RHCP in the x config.
>>
>> Question is:
>>
>> normally I would reverse the coax connections to a dipole driver but 
>> this is a hairpin (half of a folded dipole. )
>>
>> Do I reverse the connections as normal?  Kents instructions just say 
>> offset the elements and feed in phase.
>>
>> Thanks
>>
>> Curt
>> KU8L
>>
>>
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>>
>>   
>>     
>
>
>   

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