[Elecraft] OT: application of directional Quad in UHF

[David Christ]

At 70 cm element sizes are small enough that self supporting quad elements can be made with number 12 or 14 solid copper wire.  Putting a break in such an element is quite simple.  Also at that frequency a quad cam be built on a spine which is much easier than what has to be done at HF.  Also something we have done here which works quite well at 70 cm is to use a quad driven element and rod type reflector and directors.  

David K0LUM


On Apr 4, 2014, at 12:09 PM, Robert G Strickland wrote:

> Johnny...
> I have no experience with UHF quads, but I modeled, used and modified an
> HF quad for over 15 years. I now use a SkyHawk HF triband yagi. Based on
> that experience, quads require more mechanical effort for construction
> and maintenance. The form factor for a yagi is two-dimensional, while for a quad it is three-dimensional. Thus, packing, storage and transport is potentially simpler for the yagi than for the quad. Feeding a yagi is simpler than for a quad, because the yagi can use a solid driven element, while the quad generally requires a break in the driven element; this can complicate construction. Adding elements to a yagi antenna is mechanically simpler than adding elements to a quad. So, based on my HF experience - and thinking about UHF quads - I think mechanical issues might be a significant difference. At UHF a 4/5 element yagi might be easier to deal with than a 3-el quad. My opinion.
> 
> ...robert
> 
> On 4/4/2014 03:05, Johnny Siu wrote:
>> Hello Elecrafters,
>> 
>> It is off-topic and you can press 'DEL' now.
>> 
>> Hong Kong is quite a hilly place in the rural areas. Local ham
>> societies are often providing radio communication support services to
>> charity organisations having fun raising sports activities in these
>> areas.  We have to set up UHF repeaters at the hill tops.  Purely
>> from the radio text books, a 3 element quad gives better performance
>> than a 3 element yagi.  However, I seldom see using directional Quad
>> in the UHF repeaters.
>> 
>> Apart from performance, are there any disdvantages (or advantages) of
>> using directional quad instead of yagi in UHF repeaters?  Could you
>> share with me your experience in US?
>> 
>> Thanks for your help in advance and please reply off-the-list to
>> reduce the traffic in the mail listing (oh, yes, not forum!!)
>> 
>> 73
>> 
>> Johnny VR2XMC
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> 
> -- 
> Robert G Strickland, PhD ABPH - KE2WY
> rcrgs at verizon.net.usa
> Syracuse, New York, USA
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