[600MRG] Very low halfwave dipole for 630m

[Brian Pease]

I modeled my 2m high dipole in NEC4.2 over poor ground (cond=.002 S/m, 
Er=13).  At 25 degrees above the horizon the vertical E-field off the 
ends is only 4.3dB stronger than the broadside horizontal E-field.  At 
45 degrees up the horizontal field is slightly stronger than the 
vertical field.  Theory seems to confirm that the dipole is more or less 
omnidirectional for sky wave, which as been confirmed by reports.

On 3/17/2015 2:35 PM, Laurence KL7 L wrote:
> This winter season I squeezed a 600m half way dipole (first 150m was straight) into just over  2 acres avg height was 20ft agl on glaciated moraine (very poor) - i was expecting low z but it turned out near 50 ohms  due to the bent ends
>
> Now - for this location which has close in mountains in most of my favorite directions its sky wave performance to the L 48 was some avg  15dB worse than the main marconi with stations in excess on 2000kms which most are - but you have be very careful to pass absolute judgement given the iono and local topo/ground conditions stuff that goes on here. I really wasnt suprised and the dipole was turned into more radials 😄-  Ground wave was very poor too at 50 miles - again no surprises there
>
>
>
> Laurence
> Near Area 51.1 today
>
>
>
>> On Mar 17, 2015, at 11:10, Edward R Cole <kl7uw at acsalaska.net> wrote:
>>
>> Yep, no problem 10m high = 33 feet and 262m long = 860 feet.  Since a square acre is 204x204 feet one only needs about 4-1/2 acres of land (or very accommodating neighbors).
>>
>> My inverted-L is 43 feet high by 122 fee long; radials are two at 50, one 70 and one 110 foot long (all could fit on a single acre of land).  How many city dwellers own an acre?  How many own 4-1/2 acres?  This is a fine idea for you farmer-hams with your back-40 hobby farm.  My 1.75ac lot is assessed at $10.6K (my Dad's 110ac farm in MI was about $150/ac for the land).
>>
>> I tried out a 960-foot BOG (only a half wave long).  Noise was 20-dB less than the inverted-L and so were the signals.  Bad  idea (neighbor rolled my BOG up when he needed access to his land to do some logging).   Then I tried a shorter BOG confined to my 1-3/4 acre (no better).  So forget wires on ground for me.
>>
>> I am more interested in trying some small loops or "flags" for Rx.
>>
>> but my next purchase will be two new synthesizer boards ($400) for my K3 which will permit operations below 490-KHz.
>>
>> 73, Ed - KL7UW
>> .
>> At 05:28 AM 3/17/2015, sbjohnston at aol.com wrote:
>>
>>> My inverted-L antenna continues to perform well, but I came across this interesting article on using a very low halfwave dipole for operation on the 630m band:
>>>
>>> https://dl.dropboxusercontent.com/u/19882028/MF/A%20full%20size%20dipole%20for%20the%20630%20m%20band.pdf
>>>
>>> If ground conductivity is very low I bet one could just lay it on the ground.
>>>
>>>
>>>
>>>
>>> Steve WD8DAS
>>>
>>> sbjohnston at aol.com
>>> http://www.wd8das.net/
>>> --------------------------------------------------------------------
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>>>
>>>
>>>
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>> 73, Ed - KL7UW
>> http://www.kl7uw.com
>>     "Kits made by KL7UW"
>> Dubus Mag business:
>>     dubususa at gmail.com
>>
>>
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