Topband: Ground Radials and an inv-L antenna

[Dennis Peterson]

Okay guys here's the latest scenario.............because the VSWR curve looks as it does and it was checked 5 times or more for accuracy, (see attachment)
I decided to disconnect all the radials and re-check them in groups and measure the VSWR each time with the new group addition.

(1)     I started with 0 radials and measured infinite vswr
(2)     I then added 5 ground radials--------------------With the loading coil in the circuit and again with the loading coil out  (2 radials 136' and 3 @ 36')
            (The VSWR curve is as shown on the attachment)
(3)    I then added 8 more radials ----------------------making a total of 13 ground radials in the same manner as 2 above  ( all 8 radials @ 36' length)
            (virtually no significant change at all)
(4)    I added 3 more radials--------------------------- making a total of 16 ground radials in the same manner as 2 & 3 above  (all 3 radials @ 136' length)
            (virtually no significant change at all)
(5)    I added 7 more radials---------------------------making a total of 23 ground radials in the same manner as 2, 3 & 4 above ( 4 radials @ 136' & 3 @ 36")
            (virtually no significant change at all)
(6)    I added 8 more radials---------------------------making a total of 31 ground radials in the same manner as 2,3,4, & 5 above  (all 8 radials @ 36' length)
            (virtually no significant change at all)
(7)    I then added the last 2 radials--------------------making a total of 35 ground radials in the same manner as 2,3,4,5 & 6 above  (both radials @ 36' length)
            (virtually no significant change at all)


I have checked this antenna numerous times to see if there was a mistake or an error.  It showed the same results every time.  I hope to have someone come over and use an analyzer on the antenna and see exactly what is going on etc.

>From a precious discussion, the inv-L is 136 feet total length using #14 gauge insulated copper wire.  90' is vertical and 46 ' is horizontal.

In the near field their is a high voltage drop coming into the service entrance about 16 feet away.
36 feet from the feedpoint is a 35 foot pole with a mercury vapor security light
43 feet away is a 35 foot pole with a pole pig transformer and the feed lines and drop lines coming to the home
The radials are aoll faned out into a semi circular pattern due to the duplex dwelling that does not permit radial construction in the other 180 degree position

The antenna employs a relay system to switch in and out a small 4 turn loading coil wound on a 4 inch diameter piece of pvc water pipe spaced 1/2 inch between turns.   

You can see the variance of the VSWR when the coil is switched in and or out and especially out where it yields an additional range of frequencies under the 1.5:1 spectrum.

The transceiver is an IC-735 running 100 watts; but I can go down as low as 2.1 watts for QRP.

I have aKenwood TL-922 Amplifier ready to be repaired and put on line; but I want it to see a HAPPY-HEALTHY EFFICIENT antenna before I do.
There are two common mode chokes wound on two seperate 4 inch diameter pvc water pipes using 12 turns each.  The entire feedline and all jumpers (jumpers are all 6' in length) is made up of RG-213 COAXIAL CABLE; only because it was free if I'd come and get it.

Is this antenna efficient?

Is this antenna screwed up?

Is this antenna worthy of improvement?

Can adding additional radials make any differfence in the system or have I reached a point of DIMINISHING RETURNS?

Is this antenna telling me something I am not seeing or should be seeing?

I would appreciate any and all comments and suggestions with this set up.   Looking forward to hearinbg from all the EXPERTS out there with some Positive and even Negative feed back......................

de K0CKDennis







Dennis G. Peterson
326 East Jefferson Street
Apt 2
York, SC  29745
803-389-9366

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