Adapting the main HF Doublet Antenna as ‘L’ Antenna is achieved by simple connecting to one side of the ladder line in the shack directly to the T-Match antenna tuner.

The main HF antenna is an All Band Doublet fed with ladder line and matched with a T-Match antenna tuner including a 1:4 current balun giving access to all HF band including the 160m band. With a view to get better performance particularly on lower frequency bands this antenna was reconfigured as a type of ‘L’ Antenna by connecting to one side of the ladder line in the shack directly to the T-Match antenna tuner

This antenna requires a counterpoise to work well and this will achieved at least initially by using the galvanized building roof to serve this purpose.  

Fig 1 Multi-band dipole antenna configured as a type of 'L" Antenna. Note left side of the antenna and feed line not connected.

Basic All Band Dipole Arrangement

(1)  Inverted 'V' Dipole 42Mtr total length

(2)  450 Ohm Ladder Line 8Mtr length.

(3)  Junction box (Ladder line - twin heliax interface)

(4)  Twin heliax 3.5Mtr length.

(5)  Twin SO259 bulkhead sockets

(6)  T-Match Tuner. See T-Match Tuner

(7)  VSWR Meter.

(8)  HF Transceiver.

Antenna Modelling with MMANA-GAL

Fig 2 All Band Doublet modelled with MMANA-GAL in the normal configuration at 1.825MHz.

Fig 3 All Band Doublet re-configured to a 'L' Antenna and modelled with MMANA-GAL at 1.825MHz.

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