Area 51 for Antenna Modelers & Builders (See Post #1) - Page 17 - Canadian TV, Computing and Home Theatre Forums

wildwillie · 2009-08-06, 10:16 AM

x-240 is very hard to get swr<3 at 174mhz but im stil trying with a gain of 11dbi

300ohm · 2009-08-06, 03:07 PM

Yeah, it does improve vhf-hi over my post 20 here: http://www.digitalhome.ca/forum/show...t=99907&page=2

But, it knocks the uhf gain curve for a loop, heh.

wildwillie · 2009-08-06, 03:23 PM

dang 300ohms wish i would have seen your VHF_Hi before i started out and your pics now
i"ll see if NARODs can improve what you have done
Mite take me sometime but i like to play.

Now i have 2 models to go at thank you.

Well I'm working on the VHF_HI then I work on the SWR for the UHF that 473 looks to be fun

300ohm · 2009-08-06, 03:33 PM

Ramkats tophat NAROD gets rid of the dip in the uhf gain curve, and changes the SWR, but I havent modeled a vhf-hi general purpose version of it yet.

wildwillie · 2009-08-08, 03:47 PM

x-240 was lots of fun I now have the SWR <2 on VHF_HI with a gain of 9 to 10 dbi , UHF SWR <3 from 470 to 585 at time of 4Nec2 test. The gain is not that great in the UHF ,

I have not test colrods yet but i believe it may have to do with the 8 inch stubs for the gain in the UHF frequence.

But so far very pleased with the resaults .

To 300ohm's
Ramkats tophat NAROD i have not modeled yet but to use them they could be used on the top and bottom of the element layout the middle would not be needed ,I believe

Code:

CM 300ohms DBGH no reflector
CM 88mm feedgap
CM 10 gauge phasing line with 2 inch phasing line gap, 1 inch high
CM SWR <2 VHF_HI  SWR <3 UHF edit by WildWillie
CM work in progress for higher gain in the UHF
CE
GW	30	5	0	1.65338786	-15.51916	0	6.65338786	-10.51916	0.06424494
GW	31	5	0	1.65338786	-5.5191602	0	6.65338786	-10.51916	0.06424494
GW	32	5	0	1.65338786	-5.5191602	0	6.65338786	-0.5191602	0.06424494
GW	34	5	0	-1.8111791	-15.51916	0	-6.8111791	-10.51916	0.06424494
GW	35	5	0	-1.8111791	-5.5191602	0	-6.8111791	-10.51916	0.06424494
GW	36	5	0	-1.8111791	-5.5191602	0	-6.8111791	-0.5191602	0.06424494
GW	38	5	0	1.65338786	-15.51916	0	6.65338786	-20.51916	0.06424494
GW	39	5	0	1.65338786	-25.51916	0	6.65338786	-20.51916	0.06424494
GW	40	5	0	1.65338786	-25.51916	0	6.65338786	-30.51916	0.06424494
GW	42	5	0	-1.8111791	-15.51916	0	-6.8111791	-20.51916	0.06424494
GW	43	5	0	-1.8111791	-25.51916	0	-6.8111791	-20.51916	0.06424494
GW	44	5	0	-1.8111791	-25.51916	0	-6.8111791	-30.51916	0.06424494
GW	46	7	0	6.65338786	0.48083979	0	14.8422063	0.49963777	0.06424494
GW	47	7	0	-6.8111791	0.48083979	0	-15	0.5	0.06424494
GW	55	5	0	-6.8111791	0.48083979	0	-1.8111791	5.48083979	0.06424494
GW	56	5	0	6.65338786	0.48083979	0	1.65338786	5.48083979	0.06424494
GW	57	5	0	-6.8111791	30.4808398	0	-1.8111791	25.4808398	0.06424494
GW	58	5	0	6.65338786	30.4808398	0	1.65338786	25.4808398	0.06424494
GW	61	5	0	-1.8111791	5.48083979	0	-6.8111791	10.4808398	0.06424494
GW	62	5	0	1.65338786	5.48083979	0	6.65338786	10.4808398	0.06424494
GW	66	5	0	1.65338786	15.4808398	0	6.65338786	20.4808398	0.06424494
GW	67	5	0	-6.8111791	20.4808398	0	-1.8111791	25.4808398	0.06424494
GW	68	5	0	6.65338786	20.4808398	0	1.65338786	25.4808398	0.06424494
GW	69	5	0	1.65338786	15.4808398	0	6.65338786	10.4808398	0.06424494
GW	100	7	0	6.65338786	30.4808398	0	14.9211044	30.4808398	0.06424494
GW	101	7	0	-6.8111791	30.4808398	0	-15.078896	30.4808398	0.06424494
GW	103	7	0	6.65338786	-0.5191602	0	14.8422063	-0.5003622	0.06424494
GW	104	7	0	-6.8111791	-0.5191602	0	-14.999997	-0.5	0.06424494
GW	106	7	0	6.65338786	-30.51916	0	14.9211044	-30.51916	0.06424494
GW	107	7	0	-6.8111791	-30.51916	0	-15.078896	-30.51916	0.06424494
GW	121	1	0	-1.8111791	-15.51916	1	-1.0788956	-15.51916	0.0511811
GW	127	5	0	-6.8111791	20.4808398	0	-1.8111791	15.4808398	0.06424494
GW	128	5	0	-6.8111791	10.4808398	0	-1.8111791	15.4808398	0.06424494
GW	129	1	0	-1.8111791	15.4808398	1	-1.0788956	15.4808398	0.0511811
GW	110	1	0	1.65338786	-15.51916	1	0.9211044	-15.51916	0.0511811
GW	130	11	1	-1.0788956	15.4808398	1	-1.0788956	-0.0191602	0.0511811
GW	131	1	0	1.65338786	15.4808398	1	0.9211044	15.4808398	0.0511811
GW	132	11	1	0.9211044	15.4808398	1	0.9211044	-0.0191602	0.0511811
GW	133	11	1	-1.0788956	-0.0191602	1	-1.0788956	-15.51916	0.0511811
GW	134	11	1	0.9211044	-0.0191602	1	0.9211044	-15.51916	0.0511811
GW	135	1	1	-1.0788956	-0.0191602	1	0.9211044	-0.0191602	0.077
GW	137	23	0	-15.105524	0.01991814	0	14.8944768	0.01991814	0.16243037
GW	138	23	0	-16.367851	-31.26916	0	15.3821497	-31.26916	0.16243037
GW	139	9	0	-5.136885	29.6617992	0	5.48145952	29.6617992	0.16243037
GW	140	9	0	-5.4524661	-29.817157	0	5.16587802	-29.817157	0.16243037
GW	141	9	0	-4.8213023	20.2028839	0	5.7970418	20.2028839	0.16243037
GW	142	9	0	-4.9790928	-20.678878	0	5.63925125	-20.678878	0.16243037
GW	143	5	0	-3.5589743	10.4233256	0	3.90355086	10.4233256	0.16243037
GW	144	5	0	-3.7167649	-10.57868	0	3.7457607	-10.57868	0.16243037
GW	145	25	-10	-16.71006	31	-10	16.3022669	31	0.16243037
GW	146	25	-10	-16.77564	-29.869738	-10	16.2366858	-29.869738	0.1624304
GW	147	27	-10	-19.44576	0.4604224	-10	17.566537	0.4604224	0.1624304
GW	148	23	0	-16.024458	31.1524063	0	15.7255422	31.1524063	0.16243037
GW	149	21	-10	-14.525443	38.9208413	-10	13.910948	38.9208413	0.16243037
GW	150	21	-10	-13.973176	-38.107615	-10	14.463215	-38.107615	0.16243037
GW	151	23	-10	-16.02447	-31.592988	-10	16.041126	-31.592988	0.1624304
GW	152	23	-10	-16.024476	32.9701405	-10	16.041124	32.9701405	0.16243037
GW	153	23	-10	-15.55109	34.8939854	-10	15.514515	34.8939854	0.1624304
GW	154	23	-10	-15.55109	-34.639078	-10	15.514515	-34.639078	0.1624304
GW	155	23	-10	-15.10335	36.8178393	-10	14.9622461	36.8178393	0.1624304
GW	156	23	-10	-14.60434	-36.402605	-10	15.4612602	-36.402605	0.16243037
GW	157	9	-5.55	-5.8683429	16	-5.55	6	16	0.1624304
GW	158	9	-5.55	-6	15	-5.55	5.86834252	15	0.1624304
GW	159	9	-5.55	-6	-14	-5.55	5.86834331	-14	0.1624304
GW	160	9	-5.55	-6	-16	-5.55	5.8683437	-16	0.1624304
GW	161	13	-5.55	-8.391	22	-5.55	8	22	0.1624304
GW	162	13	-5.55	-8	8	-5.55	9.391	8	0.1624304
GW	163	13	-5.55	-8	-8	-5.55	9.391	-8	0.1624304
GW	164	13	-5.55	-8.391	-23	-5.55	8	-23	0.1624304
GW	165	11	-5.55	-7.4916	19	-5.55	7	19	0.1624304
GW	166	9	-5.55	-6	13	-5.55	6.916	13	0.1624304
GW	167	9	-5.55	-6	-12	-5.55	6.4916	-12	0.1624304
GW	168	11	-5.55	-7.916	-19	-5.55	7	-19	0.1624304
GW	169	13	-5.55	-9	17	-5.55	8.916	17	0.1624304
GW	170	9	-5.55	-6	12	-5.55	6.4916	12	0.1624304
GW	171	9	-5.55	-6.916	-11	-5.55	6	-11	0.1624304
GW	172	13	-5.55	-9	-18	-5.55	8.4916	-18	0.1624304
GW	173	27	-10	-19	12	-10	18.012297	12	0.1624304
GW	174	27	-10	-19	-12	-10	18.012297	-12	0.1624304
GW	175	27	-10	-19	4	-10	18.012297	4	0.1624304
GW	176	27	-10	-19	-3	-10	18.012297	-3	0.1624304
GS	0	0	0.0254		' All in in.
GE	0
EK
LD	5	0	0	0	3.77e7	0
EX	0	135	1	0	1	0
GN	-1
FR	0	1	0	0	170	0
RP 0 1 10 1510 90. 0. 0. 20. 0. 0.

j3d · 2009-08-11, 12:15 AM

Hi,

Here is a design for a 75 ohm-direct connect Hoverman-like antenna.
Because the bandwidth is limited, it optimized it for 475-600 MHz.
Later I will post a model for the higher frequencies.

The net gain peaks at about 15.6 dBi near 550 MHz. Because no
matching transformer is required, there is no loss associated with
one. Although it is a direct-connect antenna, a careful person would
attach the coax through a 1-1 balun to avoid feedline currents. But
such baluns are not easy to come by and at these frequencies, could
limit the bandwidth. If it were me, I would forego the balun.

The dGain column in the table below represents the difference between
the NetGain and RawGain columns, and reflects the mismatch loss
between the coax and the antenna. The NetGain has been AGT corrected.

Code:

 freq[MHz]        SWR    RawGain    NetGain    dGain        F/B
    471.25    3.73766      14.71    12.9453  -1.76468       9.11
    477.25     3.1019    14.8893    13.5665  -1.32283       9.21
    483.25    2.62622    15.0583    14.0831  -0.975173      9.33
    489.25    2.29346    15.2269    14.4994  -0.727536      9.5 
    495.25    2.08988    15.3854    14.8083  -0.577022      9.7 
    501.25    1.99922    15.5338    15.0228  -0.510963      9.93
    507.25    1.99592    15.6724    15.1638  -0.508575     10.2 
    513.25    2.04538    15.8013    15.2568  -0.544489     10.51
    519.25    2.11114    15.9109    15.3183  -0.592623     10.86
    525.25    2.16111    15.9915    15.3621  -0.629427     11.23
    531.25    2.17052    16.0432    15.4068  -0.636372     11.64
    537.25    2.12363    16.0561    15.4543  -0.601806     12.07
    543.25    2.01527    16.0303    15.5077  -0.52259      12.53
    549.25    1.85103    15.9655    15.5602  -0.405303     13.02
    555.25    1.64573    15.8715    15.6047  -0.266725     13.52
    561.25    1.4196     15.7278    15.5952  -0.132611     14.01
    567.25    1.19364    15.554     15.52    -0.0339743    14.47
    573.25    1.0218     15.3299    15.3294  -0.00050478   14.85
    579.25    1.24655    15.0753    15.0226  -0.0526255    15.13
    585.25    1.53094    14.78      14.5846  -0.195456     15.27
    591.25    1.87293    14.4641    14.0434  -0.420688     15.14
    597.25    2.30236    13.8344    13.1002  -0.734156     13.53

Here is the NEC file:

Code:

CM Model: DC-8-UHFlo
CE
GW 1 19 0.101018 -0.0392186 0 0.101018 0.0392186 0 0.00205769
GW 2 19 0.101018 -0.0392186 0 0.0591873 -0.113347 0 0.00205769
GW 3 19 0.101018 0.0392186 0 0.0591873 0.113347 0 0.00205769
GW 4 25 0.101018 -0.0392186 0 0 -0.0127103 0 0.00205769
GW 5 25 0.101018 0.0392186 0 0 0.0127103 0 0.00205769
GW 6 103 0 -0.0127103 0 0 -0.344589 0.274073 0.00205769
GW 7 103 0 -0.0127103 0 0 -0.344589 -0.274073 0.00205769
GW 8 103 0 0.0127103 0 0 0.344589 0.274073 0.00205769
GW 9 103 0 0.0127103 0 0 0.344589 -0.274073 0.00205769
GW 10 59 0 -0.344589 0.274073 0 -0.153102 0.432208 0.00205769
GW 11 59 0 -0.344589 -0.274073 0 -0.153102 -0.432208 0.00205769
GW 12 59 0 0.344589 0.274073 0 0.153102 0.432208 0.00205769
GW 13 59 0 0.344589 -0.274073 0 0.153102 -0.432208 0.00205769
GW 14 45 0 -0.153102 0.432208 0 -0.29621 0.55039 0.00205769
GW 15 45 0 -0.153102 -0.432208 0 -0.29621 -0.55039 0.00205769
GW 16 45 0 0.153102 0.432208 0 0.29621 0.55039 0.00205769
GW 17 45 0 0.153102 -0.432208 0 0.29621 -0.55039 0.00205769
GW 18 23 0 -0.29621 0.55039 0 -0.397516 0.55039 0.00205769
GW 19 23 0 -0.29621 -0.55039 0 -0.397516 -0.55039 0.00205769
GW 20 23 0 0.29621 0.55039 0 0.397516 0.55039 0.00205769
GW 21 23 0 0.29621 -0.55039 0 0.397516 -0.55039 0.00205769
GW 22 87 -0.0867753 -0.6096 -0.544908 -0.0867753 0 -0.544908 0.0035
GW 23 87 -0.0867753 0 -0.544908 -0.0867753 0.6096 -0.544908 0.0035
GW 24 87 -0.0867753 -0.6096 -0.413654 -0.0867753 0 -0.413654 0.0035
GW 25 87 -0.0867753 0 -0.413654 -0.0867753 0.6096 -0.413654 0.0035
GW 26 87 -0.0867753 -0.6096 -0.267001 -0.0867753 0 -0.267001 0.0035
GW 27 87 -0.0867753 0 -0.267001 -0.0867753 0.6096 -0.267001 0.0035
GW 28 67 -0.0867753 -0.476333 -0.0984601 -0.0867753 0 -0.0984601 0.0035
GW 29 67 -0.0867753 0 -0.0984601 -0.0867753 0.476333 -0.0984601 0.0035
GW 30 67 -0.0867753 -0.476333 0.0984601 -0.0867753 0 0.0984601 0.0035
GW 31 67 -0.0867753 0 0.0984601 -0.0867753 0.476333 0.0984601 0.0035
GW 32 87 -0.0867753 -0.6096 0.267001 -0.0867753 0 0.267001 0.0035
GW 33 87 -0.0867753 0 0.267001 -0.0867753 0.6096 0.267001 0.0035
GW 34 87 -0.0867753 -0.6096 0.413654 -0.0867753 0 0.413654 0.0035
GW 35 87 -0.0867753 0 0.413654 -0.0867753 0.6096 0.413654 0.0035
GW 36 87 -0.0867753 -0.6096 0.544908 -0.0867753 0 0.544908 0.0035
GW 37 87 -0.0867753 0 0.544908 -0.0867753 0.6096 0.544908 0.0035
GE 0
EK 0
FR 0 39 0 0 471.25 6
EX 0 1 10 0 1
GN -1 0 0 0 0.0 0.0  0.0  0.0  0.0  0.0
RP 0 60 73 1001 0 0 3 5
EN

--John

300ohm · 2009-08-11, 01:06 AM

Quote:

Although it is a direct-connect antenna, a careful person would
attach the coax through a 1-1 balun to avoid feedline currents. But
such baluns are not easy to come by and at these frequencies, could
limit the bandwidth. If it were me, I would forego the balun.

My recent builds of wifi biquad antennas without baluns, while still good, leads me to believe that there is a very significant penalty to be paid without a balun to go from a balanced antenna to the unbalanced coax, thats not reflected in the net gain calculation.

Of course, I have no test equipment. I have to judge comparing a 2dbi (stated) Rosewill rubber ducky antenna which is connected up with a meter of RG174U coax, which easily knocks a dbi off, leaving about 1dbi at the wifi card input, heh. And in Ubuntu, I use RutiL for the signal measurement.
My biquads, per modeling, should be about 10 to 11 dbi. They are connected up with 2 meters of RG58U coax, also a loss of about a dbi, but better than RG174U. My builds are pretty exacting, I would say within .5mm. (Will post pictures of latest build later) But, all in all, Im not seeing the 9 dbi difference in gain I should. I think a good portion of that may be due to a lack of balun.

j3d · 2009-08-11, 03:21 AM

Quote:

Originally Posted by 300ohm

My recent builds of wifi biquad antennas without
baluns, while still good, leads me to believe that there is a very
significant penalty to be paid without a balun to go from a balanced
antenna to the unbalanced coax, thats not reflected in the net gain
calculation.

I imagine that those building these high-gain antennas are using a
preamp. It seems to me that much of the feedline radiation could be
choked off by properly choosing the length of cable connecting the
antenna to the preamp. Also the coax should drop vertically from the
feed point and be properly centered.

Quote:

My biquads, per modeling, should be about 10 to
11 dbi. They are connected up with 2 meters of RG58U coax, also a loss
of about a dbi, but better than RG174U. My builds are pretty exacting,
I would say within .5mm. (Will post pictures of latest build later)
But, all in all, Im not seeing the 9 dbi difference in gain I should.
I think a good portion of that may be due to a lack of balun.

Have you tried playing with the length of the coax?

Also, how confident are you in the accuracy of NEC-2 at such
frequencies?

Thanks,
--John

Xauto · 2009-08-11, 07:48 AM

John: What is the stuff in the +X? The first part could be a 1/4 wave matching section, but what are the tails(another 1/4 wave stub)?

300ohm · 2009-08-11, 09:48 AM

Quote:

Have you tried playing with the length of the coax?

Not yet, but I was thinking the same thing. Maybe some air loops or loops around a ferrite core. Not as easy as aluminum foil around twinlead, heh.

Quote:

Also, how confident are you in the accuracy of NEC-2 at such
frequencies?

For the 2.4Ghz biquad style antenna, pretty confident. (other styles/types like the slotted waveguides or patch antenna types, NEC2 isnt that good on)
Others have done some pretty good analysis on the Trevor Marshall 2.4Ghz biquad too. http://www.lecad.uni-lj.si/~leon/other/wlan/biquad/
I followed those guidelines on my last build.

j3d · 2009-08-11, 09:51 PM

Quote:

Originally Posted by Xauto

John: What is the stuff in the +X? The first part
could be a 1/4 wave matching section, but what are the tails(another
1/4 wave stub)?

Whiskers? I added them in an attempt to increase the bandwidth. They
also seemed to help the gain a bit. --John

j3d · 2009-08-12, 12:29 PM

As promised, here is a 75 ohm design optimized for the 600-700 MHz
band. Ideally, it should be used with a 1-1 balun (see the earlier
discussion). The netgain near 16 dBi over much of the band.

Code:

 freq[MHz]        SWR    RawGain    NetGain      dGain        F/B
    597.25    2.29267    15.5086    14.7817  -0.726948       8.96
    603.25    2.05005    15.2912    14.7433  -0.547893      10.16
    609.25    2.08993    15.6546    15.0775  -0.577057       8.48
    615.25    1.70381    16.1806    15.8758  -0.304714       7.99
    621.25    1.54366    16.3003    16.0973  -0.203063       8.26
    627.25    1.51274    16.3601    16.1754  -0.184706       8.59
    633.25    1.55366      16.41    16.2009  -0.209104       8.97
    639.25    1.61952    16.4404    16.1904  -0.249972       9.38
    645.25    1.67786    16.4417    16.1541  -0.287597        9.8
    651.25    1.70855    16.4242    16.1163  -0.307862      10.26
    657.25    1.70052    16.3781    16.0756   -0.30253      10.74
    663.25    1.65007    16.3034    16.0339  -0.269526      11.25
    669.25    1.56028    16.1899    15.9768  -0.213122      11.77
    675.25    1.43962    16.0474     15.904  -0.143366      12.31
    681.25    1.30052    15.8653    15.7906 -0.0747478      12.86
    687.25    1.16002    15.6534    15.6295 -0.0239009       13.4
    693.25    1.08157    15.4212    15.4145 -0.00667341     13.92
    699.25    1.19755    15.1584    15.1231 -0.0352388      14.41

Here is the NEC file:

Code:

CM Model: DC-8-UHFhi
CE
GW 1 13 0.0790197 -0.0307354 0 0.0790197 0.0307354 0 0.00205769
GW 2 17 0.0790197 -0.0307354 0 0.0460475 -0.0944725 0 0.00205769
GW 3 17 0.0790197 0.0307354 0 0.0460475 0.0944725 0 0.00205769
GW 4 19 0.0790197 -0.0307354 0 0 -0.0127175 0 0.00205769
GW 5 19 0.0790197 0.0307354 0 0 0.0127175 0 0.00205769
GW 6 89 0 -0.0127175 0 0 -0.303555 0.228222 0.00205769
GW 7 89 0 -0.0127175 0 0 -0.303555 -0.228222 0.00205769
GW 8 89 0 0.0127175 0 0 0.303555 0.228222 0.00205769
GW 9 89 0 0.0127175 0 0 0.303555 -0.228222 0.00205769
GW 10 45 0 -0.303555 0.228222 0 -0.151483 0.347555 0.00205769
GW 11 45 0 -0.303555 -0.228222 0 -0.151483 -0.347555 0.00205769
GW 12 45 0 0.303555 0.228222 0 0.151483 0.347555 0.00205769
GW 13 45 0 0.303555 -0.228222 0 0.151483 -0.347555 0.00205769
GW 14 37 0 -0.151483 0.347555 0 -0.271706 0.441894 0.00205769
GW 15 37 0 -0.151483 -0.347555 0 -0.271706 -0.441894 0.00205769
GW 16 37 0 0.151483 0.347555 0 0.271706 0.441894 0.00205769
GW 17 37 0 0.151483 -0.347555 0 0.271706 -0.441894 0.00205769
GW 18 15 0 -0.271706 0.441894 0 -0.341595 0.441894 0.00205769
GW 19 15 0 -0.271706 -0.441894 0 -0.341595 -0.441894 0.00205769
GW 20 15 0 0.271706 0.441894 0 0.341595 0.441894 0.00205769
GW 21 15 0 0.271706 -0.441894 0 0.341595 -0.441894 0.00205769
GW 22 85 -0.0635445 -0.597882 -0.450593 -0.0635445 0 -0.450593 0.0035
GW 23 85 -0.0635445 0 -0.450593 -0.0635445 0.597882 -0.450593 0.0035
GW 24 87 -0.0635445 -0.6096 -0.374587 -0.0635445 0 -0.374587 0.0035
GW 25 87 -0.0635445 0 -0.374587 -0.0635445 0.6096 -0.374587 0.0035
GW 26 83 -0.0635445 -0.592336 -0.257565 -0.0635445 0 -0.257565 0.0035
GW 27 83 -0.0635445 0 -0.257565 -0.0635445 0.592336 -0.257565 0.0035
GW 28 51 -0.0635445 -0.366453 -0.0995267 -0.0635445 0 -0.0995267 0.0035
GW 29 51 -0.0635445 0 -0.0995267 -0.0635445 0.366453 -0.0995267 0.0035
GW 30 51 -0.0635445 -0.366453 0.0995267 -0.0635445 0 0.0995267 0.0035
GW 31 51 -0.0635445 0 0.0995267 -0.0635445 0.366453 0.0995267 0.0035
GW 32 83 -0.0635445 -0.592336 0.257565 -0.0635445 0 0.257565 0.0035
GW 33 83 -0.0635445 0 0.257565 -0.0635445 0.592336 0.257565 0.0035
GW 34 87 -0.0635445 -0.6096 0.374587 -0.0635445 0 0.374587 0.0035
GW 35 87 -0.0635445 0 0.374587 -0.0635445 0.6096 0.374587 0.0035
GW 36 85 -0.0635445 -0.597882 0.450593 -0.0635445 0 0.450593 0.0035
GW 37 85 -0.0635445 0 0.450593 -0.0635445 0.597882 0.450593 0.0035
GE 0
EK 0
FR 0 39 0 0 471.25 6
EX 0 1 7 0 1
GN -1 0 0 0 0.0 0.0  0.0  0.0  0.0  0.0
RP 0 60 73 1001 0 0 3 5
EN

Thanks,
--John

bokakob · 2009-08-12, 02:24 PM

Hello everyone, recently I made an antenna from a thick copper electrical wire. It is vertically oriented in “double bi-quad” shape with 120 mm between center lines of each square side. There is a reflector located behind the antenna. This reflector is made of pretty dense galvanized mesh 10mm x 10mm. The distance is 67 mm from the center line of the antenna to the mesh. The antenna feed is connected with 4:1 balun in the middle made of RG-59 TV-cable. It works exceptionally well and pulls in just under 20 stations. I can not evaluate this antenna and ask for help if someone with proper knowledge would run this setup through any digital simulation program. Any help is appreciated -- thanks.

300ohm · 2009-08-12, 02:31 PM

Basically, a biquad with solid reflector produces about 10 to 11 dbi in gain, with a nice wide round pattern. A double biquad, about 13 dbi, but if all quads are the same, the bandwidth is low. Look here, post 32 and 34, for a wide band double biquad type : http://www.digitalhome.ca/forum/show...=105660&page=3

vk3mn · 2009-08-12, 10:05 PM

Bob
what instructions were you building from that says to connect a 4:1 balun to the feed point of a “double bi-quad” ???

2009-08-06, 03:07 PM	#242
300ohm Veteran Join Date: Mar 2008 Location: Somewhere in Delaware on the flat side Posts: 7,035	Yeah, it does improve vhf-hi over my post 20 here: http://www.digitalhome.ca/forum/show...t=99907&page=2 But, it knocks the uhf gain curve for a loop, heh. __________________ My builds/plans (not the latest models) are located here.

2009-08-06, 03:33 PM	#244
300ohm Veteran Join Date: Mar 2008 Location: Somewhere in Delaware on the flat side Posts: 7,035	Ramkats tophat NAROD gets rid of the dip in the uhf gain curve, and changes the SWR, but I havent modeled a vhf-hi general purpose version of it yet. __________________ My builds/plans (not the latest models) are located here.

2009-08-12, 02:24 PM	#253
bokakob Join Date: Aug 2009 Posts: 123	Vertical Bi-Quad Hello everyone, recently I made an antenna from a thick copper electrical wire. It is vertically oriented in “double bi-quad” shape with 120 mm between center lines of each square side. There is a reflector located behind the antenna. This reflector is made of pretty dense galvanized mesh 10mm x 10mm. The distance is 67 mm from the center line of the antenna to the mesh. The antenna feed is connected with 4:1 balun in the middle made of RG-59 TV-cable. It works exceptionally well and pulls in just under 20 stations. I can not evaluate this antenna and ask for help if someone with proper knowledge would run this setup through any digital simulation program. Any help is appreciated -- thanks.

2009-08-12, 02:31 PM	#254
300ohm Veteran Join Date: Mar 2008 Location: Somewhere in Delaware on the flat side Posts: 7,035	Basically, a biquad with solid reflector produces about 10 to 11 dbi in gain, with a nice wide round pattern. A double biquad, about 13 dbi, but if all quads are the same, the bandwidth is low. Look here, post 32 and 34, for a wide band double biquad type : http://www.digitalhome.ca/forum/show...=105660&page=3 __________________ My builds/plans (not the latest models) are located here.

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2009-08-06, 10:16 AM	#241
wildwillie Join Date: Jan 2009 Posts: 280	x-240 is very hard to get swr<3 at 174mhz but im stil trying with a gain of 11dbi

2009-08-06, 03:23 PM	#243
wildwillie Join Date: Jan 2009 Posts: 280	dang 300ohms wish i would have seen your VHF_Hi before i started out and your pics now i"ll see if NARODs can improve what you have done Mite take me sometime but i like to play. Now i have 2 models to go at thank you. Well I'm working on the VHF_HI then I work on the SWR for the UHF that 473 looks to be fun

2009-08-11, 07:48 AM	#249
Xauto Join Date: Sep 2008 Posts: 489	John: What is the stuff in the +X? The first part could be a 1/4 wave matching section, but what are the tails(another 1/4 wave stub)?

2009-08-12, 10:05 PM	#255
vk3mn Rookie Join Date: Aug 2009 Posts: 2	Bob what instructions were you building from that says to connect a 4:1 balun to the feed point of a “double bi-quad” ???