[Hi-zreceivingarraydiscussions] DIRECTIVITIY 8 CIRCLE

[Dave Anderson, K4SV]

Hi Everyone,

I have had my 200' 8 circle for nearly 2 years now.  In my case I have installed my 4 square inside of the 8 circle.  This allows me to have both controllers in the same cabinet. 

For 160 meters,
The 4 square works very well with great F/B.  My 8 circle works well but depending on the arrival angle of the signals the F/B varies.  I do not think the 8 circle has ever has 30+ DB of F/B.  I am using a ~3 foot 5/8" ground rod (8 foot rod cut into three pieces) for each antenna.  My array is out all by itself away from any metal objects on a small hill.

Lee's comment about it should have a 30+ DB F/B is interesting.  If grounding is the key I will go out tomorrow and add more ground rods/radials and give it a try to see if it will indeed improve F/B.  Comments?

My 8 circle works not bad on 80 meters either, directional too.

When I test my 8 circle/4 square and other receive antennas for F/B I try to do this during the middle of the day using ground wave from an AM broadcast station 100 miles away or so.  This was suggested by Jose N4IS when testing the Waller Flag I built.  When using an application called Polar plot and testing the WF I can easily see the pattern of the WF.  This might be a trick that can be used to check F/B on other receive antennas. 

I have attached a plot of the 8 circle when using Polar Plot.  Once I started Polar Plot I switched the 8 circle through its range.  You can read the F/B from an AM station some 80 miles away.

Comments?
 
Dave Anderson, K4SV
Tryon, NC
 828 777-5088
 
www.K4SV.net
 



On Saturday, November 30, 2013 6:54 PM, kd9sv <kd9sv at comcast.net> wrote:
 
Lee, 30db F/B is about what I am seeing on my 4sq with 80ft/side which is
>located about 400ft in the clear in an open field...de gary
>
>-----Original Message-----
>From: Hi-zreceivingarraydiscussions
>[mailto:hi-zreceivingarraydiscussions-bounces at hizantennas.com] On Behalf Of
>Lee K7TJR
>Sent: Saturday, November 30, 2013 5:56 PM
>To: 'Hi-Z Receiving Array Discussions'
>Subject: Re: [Hi-zreceivingarraydiscussions] DIRECTIVITIY 8 CIRCLE
>
>This will be an interesting thread. The Hi-Z 8A was only designed to work on
>a single band, but to produce the best SNR currently available on that band.
>I suspect your observations are what I would expect on other bands. If
>operating on multiple bands, I would suggest changing over to a 4-8Pro which
>is a 3 band array and shows reasonable directivity on all three. With of
>course, slightly less available SNR of received signals than the single band
>array.
>   All that being said, I have heard that the 8A actually hears reasonably
>well on 80 Meters while not showing much directivity.
>I personally have not seen the need for common mode protection however
>every install is usually different. If you are seeing 30+ dB of front to
>back ratio on 160 meters I suspect your ground rods are quite adequate.
>
>What say others?
>
>Lee  K7TJR
>
>-----Original Message-----
>From: Hi-zreceivingarraydiscussions
>[mailto:hi-zreceivingarraydiscussions-bounces at hizantennas.com] On Behalf Of
>k4pi at bellsouth.net
>Sent: Saturday, November 30, 2013 2:13 PM
>To: hi-zreceivingarraydiscussions at hizantennas.com
>Subject: [Hi-zreceivingarraydiscussions] DIRECTIVITIY 8 CIRCLE
>
>I have an 8 circle in 200 ft diameter.  I notice the F/B and F/S are mainly
>only good on 160.  Even on the upper portion of the BC band for the most
>part the F/B is not great.  Not that I need this but I have used Hi Z 4
>squares with 90 ft on a side and they seem to have good F/B on the BC band
>and other bands.  On 80 with the 8 circle I can tell the most predominant
>direction of a station but there is little F/B and F/S.  Just wondering if
>this is what others are seeing.  It receives fine.  
>
>I am well pleased with the system but just wondered what others were seeing.
>I am using only a single 4 ft ground rod and wondered if anyone else had
>seen any improvement of the system with more ground rods.  Also wondered if
>anyone else was using common mode chokes in the feed line as recommended by
>ON4UN's Low Band DXing book.  I have one at the receiver end built from K9YC
>data.  My feedline is about 450 ft long being cable TV hardline.  It is
>grounded once in the middle.
>
>Would like to hear from others on their experience.  
>
>73 Mike K4PI
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