40metres to 10 metres Long Wire Antenna [Aerial]
The“Bundu Basher” came into being because of a need for an extremelysimple antenna that could be used by caravaners, campers, holidaymakers, and even an almost invisible device that could be used in aretirement village complex, as a fixed antenna, where no big antennasor towers are allowed.
Thisantenna is so simple; it consists of a matching toroidal transformerbuilt into a waterproof ABS plastic housing, a radiator wire of about22 metres long, a counterpoise wire of 4 metres long and a SO239coaxial socket to feed the transceiver. Please note that only 40m,20m, 15m, and 10m can be used, as they are harmonically related, forother bands – use an antenna tuner.
Theantenna has been successfully tested at Ramsgate, KwaZulu SouthCoast, the Drakensberg near Champagne Castle, and Honeydew inGauteng, with extraordinary results, particularly from theDrakensberg where “man-made noise” is virtually non-existent,ideal for test purposes.
Theantenna was tried at heights of 2 metres, 2.5 metres, 3.5 metres and8m above ground level. The SWR on all bands remained very constant inall cases.
Anideal mounting would be as high as possible – can be horizontal toground level or as a sloper from a suitable pole or tree. Using the Bundu Basher Aerial on 80 metres.[PDF]
Contacts;first time out:
On20 metres, with a power of 50 watts: (Drakensberg)
Naples– Italy 5 & 6 on SSB
Tsumeb– Namibia 5 & 8 on SSB
ReunionIsland 5 & 6 on SSB
On40 metres, with a power of 50 watts:(Drakensberg)
Hoedspruit5 & 9 on SSB
PortElizabeth 5 & 8 on SSB
Ficksburg5 & 9 + on SSB
Eshowe5 & 9 + on SSB
Theantenna is capable of handling 100 watts on SSB.
Oncetuned, the antenna has outstanding SWR figures throughout the band,as indicated below on a graph supplied, by Nic van Duffelen, ZR6AEZ –Senior Radio Engineer at a large two-way radio company in JHB.
Testsconducted on the BiCraft “Bundu Basher” Antenna
[Thesemeasurements were made on very sophisticated RF laboratory testequipment. Thanks Nic!]
Tuningthe antenna is relatively easy, in that one would need the use of anaccurate SWR Meter, or something similar to the MFJ Antenna Tunerunit.
Theantenna is initially tuned on 40metres, and because the hamfrequencies mentioned above are harmonically related, all the otherbands fall into place as far as SWR is concerned. (See graph)
Itis however, to be noted that the SWR on 80 metres and 160 metres isway out – no tests were conducted with an antenna tuner to trythese two bands!
Pleasenote; below that each peak is a high SWR and each dip is the lowestSWR for each ham band, as indicated in the adjacent table of thegraph.
Testsat various heights were conducted, and there was very little changein the SWR levels.
Installingyour “Bundu Basher Antenna”
Finda suitable place to mount/hang the plastic housing of the antenna –this could be in your ceiling, or under the eaves of you house, youdecide.
Stringthe 22 metres of cable out in a straight line – if possible; at aminimum of 2metres above ground level. The counterpoise can be strungout on the ground, or hanging down from the eaves, or just danglingloosely in the ceiling, it may also be electrically attached to a“copper weld” earth spike. Six to eight metres of RG58 or aheavier coax may be used to feed the transceiver.
Attachan SWR meter between the transceiver and the antenna SO239 socket.
Selectthe 40 metre band, and apply a low level CW signal to the antenna. Ifthe SWR is low, say below 1.8, then the antenna is OK, and thebalance of the bands, i.e. 20, 15, & 10 metres will all line upwith almost the same SWR readings. (10m maybe a bit higher)
Shouldthe SWR be too high, then proceed by trimming the 22 metre length by15 centimetres at a time, until the SWR is satisfactory. Do not trimthe counterpoise!
Thehigher the antenna is above ground level the better!
Whentested at various heights up to about 8-metres, the SWR did notchange significantly.
Testswere also conducted with bends in the radiator wire, without anymajor changes in the SWR.
Itwould be advisable, as with any antenna, to disconnect during anystormy weather conditions!
Theend of the radiator wire must have an insulator attached beforetying to any object.
Tryto keep the radiator away from metal objects as much as possible.
Thedirection of the radiator did not seem to matter.
Thereare several “lobes/nodes” on the sides of the antenna wire wherethere will be better radiation than in other positions. See detailson the Internet.
Internaltoroid matching transformer.
22metres of 1mm flexible cable terminated with an “eye” crimpconnector.
4metres of 1mm flexible cable terminated with an “eye” crimpconnector.
AnIP64 100x100x50 mm plastic housing, with connectors.
Price:R395.00 collect from Honeydew Gauteng or add R99.00 Postnet anywhere in RSA.
Landline:011 958 1479 Mobile Phone: 083 625 0294
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