high-frequency

some developments:
converter
VLF-converter for receivers
active antenna for shortwave
active JFET-antenna with discret components 10 kHz - 120 MHz
active JFET-antenna with BF862 10 kHz - 30 MHz
active JFET-antenna with gain BF862 10 kHz - 88 MHz
active JFET-antenna with AD8009AN 10 kHz - 120 MHz
active JFET-antenna with OPA659 10 kHz - 40 MHz
active MOS-FET-antenna 10 kHz - 120 MHz
active MOS-FET-antenna with gain
active tube-antenna 10 kHz - 30 MHz, cascode, transformerless
active tube-antenna 10 kHz - 40 MHz, cathode-base, transformerless
active tube-antenna 10 kHz - 70 MHz, cathode-base
active tube-antenna 10 kHz - 120 MHz, cathode-base
active wideband antenna
active wideband vertical-antenna 100 MHz - 2 GHz
other
cross-dipol for 137.5 MHz
500 W RMS antenna-matchbox


VLF-converter for extreme standards

The VLF-converter expends the frequency-area of professional radio-receivers. It works with all receivers, which do not receive a signal between 1 MHz and 1.112 MHz without antenna. Best example is The JRC NRD 545 DSP. The converter is an combination between active antenna with high-inductive passive coil and mixer. Frontend and mixer are designed symmetrical, so only the signal-difference from the antenna-cable is amplified. The fitting from the antenna to the lp-filter 5th order is active. The mixer works active, too, no disadvantabe because the high outside noise-level in this frequency-area. The decrease of the effective high of the antenna, increasing of receiving-wavelenght is balanced with a lp-filter in combination with the output-amplifier, so a constant gain results. The electronic amplification can be adjusted from +3 dB to + 33 dB. Delivered are two passive antenna-coils (20 cm x 20 cm x 2.6 cm), which can positioned without disadvantage within non-steel-buildings. By positioning with an angle of 90 degree, neerly round-receiving-characteristic is possible. By parallel positioning an antenna-gain of + 3 dB can be adjusted.

example of receiving-power:

The ground-wave of the station DCF 77, with the carrier of 77.5 kHz can be received with S 9, (typ. S 9+10 dB) in an distance of 215 km. This values are for an adjusted electronical-amplification of + 3 dB and one antenna in the direction of the station. The NRD 545 was used adjusted to cw-receiving with an if-band of 2.4 kHz. The antenna was positioned in the first floor of a conventional building.

Specifications:
antenna-gain: 1.5 dB (90 degree) or 3 dB (parallel)

no tuning

input-frequency: 40 Hz - 112 kHz

output-frequency: 1.000040 MHz - 1.112 MHz (-3 dB)

electronical amplification: using-band +3 dB bis +33 dB, 1.112 MHz -135 dB

disturbing: 1 MHz, 1 MHz-fin, 2 MHz+-fin, 3 MHz+-fin ...

input-resistance: 35250 Ohm, terminal, symmetrical

antenna-combination: inductive 18.88 mH with 20.6 Ohm

output-resistance: 50 Ohm, BNC, koax

power: 230 V ~ / 50 Hz / 3 W

CE-conform

circuit diagram:

[beginning][home]


high sensitive active antenna 10 kHz - 120 MHz

This antenna is constructed to optimize the sensitivity by choosing the max. signal to noise relation. The electronic circuit can be devided in 2 parts. Input-amplification and power-amplification. Input is an n-channel-FET with FET current source and following collektor stage. The power amplifier is a class A amplifier build with 6 high-frequency transistors and an output resistance of 50 Ohm. No integrated circuits are used. Tests with bootrtrapping at input stage failed because of transadmittance of the JFET. Experiments with a bipolar transistor at the gate of the input JFET causes worse results for the input impedance as without. The passive antenna is a ground-plane with a high capacitive beam (150 mm) and a resonance-wavelenght of 2.5 m (120 MHz).

The circuit is optimized for min. intermodulation with the PSpice computer-program.

Specifications:

bandwidth: 10 kHz - 120 MHz

electronical amplification: -6.4 dB

equiv. input-noise voltage: 7.2 nV/SQRT(Hz) @ 1 MHz

intermodulation 2. order (ui~100 uV, 1 MHz / 2 MHz): -70 dB

max. EMF rms: 5.7 V/m

power: 97 mA at 14-35 V over power-supply 230 V

output resistance: 50 Ohm

dimensions: 2220 mm x 1050 mm

vertical antenna

sky-wave antenna

circuit diagram:

gain:

intermodulation:

[begin][home]


high sensitive active antenna BF862 10 kHz - 30 MHz

This antenna is constructed to optimize the sensibility by choosing the max. signal to noise ratio. The used low noise JFET BF862 has a high transfer admittance and can drive 50 Ohm load if the operational point is adjusted correctly. Because of the low noise of the BF862 it is possible to use very short passive antenna within 10 kHz to 30 MHz (82 mm x 200 mm, a flat cylinder structure). Disadvantage of this JFET is its high input capacity. The design of this antenna is critical. Optimal height the amplifier is connected to the passive antenna is in a height of 49 mm, there is the antenna capacity max.

Calculation of a passive antenna for this: [here].
Calculation of a flat cylinder structure for this: [here].

Specifications:

bandwidth: 10 kHz - 30 MHz or more with another passive antenna

electronical amplification: -6.3 dB

antenna gain: 3.2 dBi

equiv. input-noise voltage: 1.5 nV/SQRT(Hz) @ 1 MHz

max. EMF rms: 12 Veff./m

intermodulation 2. and 3. order (ui~100 uV, 1 MHz, 2 MHz): -73 dB and -73 dB

sensitivity for 20 dB S/N_hf 2.7 kHz SSB: 0.93 uV (~ field force E= 23.1 uVeff/m)

sensitivity for 14 dB S/N_hf 2.7 kHz SSB: 0.47 uV (~ field force E= 11.7 uVeff/m)

power: 12 V / 9 mA

output resistance: 50 Ohm

einen circuit diagram:

gain:

intermodulation:

output impedance:

[begin][home]

high sensitive active antenna with gain with BF862 10 kHz - 88 MHz

This antenna is constructed to optimize the sensibility by choosing the max. signal to noise ratio. The used JFET BF862 is low noise. Because of the low noise of the BF862 it is possible to use very short passive antenna within 10 kHz to 30 MHz 262 mm. For a cylinder antenna with 200 mm diameter the amplification is 14 dB because of the antenna capacity. For a whip antenna an amplification of 9.6 dB. However the gain of a whip antenne is 3 dB higher.

Calculation of a passive antenna for this: [hier].
Calculation of a flat cylinder structure for this: [here].

Specifications:
cylinder antennawhip antenna

bandwidth: 10 kHz - 88 MHz

electronical amplification: 9.6 - 14 dB (depending on antenna)

antenna gain: 1.7 - 4.7 dBi (depending on antenna)

equiv. input-noise voltage: 6.7 nV/SQRT(Hz) @ 1 MHz

max. EMF rms: 1.3 Veff./m

intermodulation 2. and 3. order (ui~100 uV, 1 MHz, 2 MHz): -80 dB u. -61 dB

sensitivity for 20 dB S/N_hf 2.7 kHz SSB: 0.68 uV (~ field force E= 5.2 uVeff/m)

sensitivity for 14 dB S/N_hf 2.7 kHz SSB: 0.34 uV (~ field force E= 2.8 uVeff/m)

power: 12 V / 32 mA

output resistance: 50 Ohm

ciruit diagram:

gain:

intermodulation:

output impedance:

Layout 112 mm x 53 mm:

[begin][Anfang]


high sensitive active antenna 10 kHz - 120 MHz

This antenna is constructed to optimize the sensitivity by choosing the max. signal to noise relation. The electronic circuit can be devided in 2 parts. Input-amplification and power-amplification. Input is an n-channel-FET with FET current source. The power amplifier is an AD8009AN from Analog Devices. The passive antenna is a ground-plane with a high capacitive beam (150 mm) and a resonance-wavelenght of 2.5 m (120 MHz).

Specifications:

bandwidth: 10 kHz - 120 MHz

electronical amplification: -6.1 dB

equiv. input-noise voltage: 7.7 nV/SQRT(Hz) @ 1 MHz

intermodulation 2. order (ui~100 uV, 1 MHz / 2 MHz): -70 dB

max. EMF rms: 2.3 V/m

power: 12 V / 16 mA

output resistance: 50 Ohm

dimensions: 2220 mm x 1050 mm

circuit diagram:

gain:

intermodulation:

[begin][home]


high sensitive active antenna 10 kHz - 40 MHz

This antenna is constructed to optimize the sensitivity by choosing the max. signal to noise relation. Used is a one stage JFET operational amplifier with an amplification of 14.8 dB that is more common for far-field usage of transmitting antennas. The OPA659 is a high impedance input amplifier with all inputs saved with diodes.

Specifications:

bandwidth: 10 kHz - 400 MHz

electronical amplification: 14.8 dB

equiv. input-noise voltage: 8.6 nV/SQRT(Hz) @ 1 MHz

intermodulation 2. order (ui~100 uV, 1 MHz / 2 MHz): -65 dB

max. EMF rms: 0.8 V/m

power: 12 V / 30 mA

output resistance: 50 Ohm

dimensions: 2220 mm x 1050 mm

circuit diagram:

gain:

intermodulation:

[begin][home]


sensitive active MOS antenna 10 kHz - 120 MHz

This antenna is constructed to optimize the sensitivity by choosing the max. signal to noise relation. The electronic circuit is reduced to one dual gate MOS-transistor, a BF908 by NXP. This is possible because of the increased transfer admittance of the transistor, which can adjusted so, that the output impedance ist exactly 50 Ohms. Noise and intermodulation are better than of the AA120-antenna.

Specifications:
calculated vertical-diagrams:

bandwidth: 10 kHz - 120 MHz

elektronical amplification: -5.6 dB

equiv. input-noise voltage: 2.1 nV/SQRT(Hz) @ 1 MHz

max. EMF rms: 0.9 V/m

intermodulation 2. order (ui~100 uV, 1 MHz, 2 MHz): -73 dB

power: 8 mA at 14-25 V over power-supply 230 V

output resistance: 50 Ohm

dimensions: 870 mm x 80 mm

circuit diagram:

gain:

intermodulation:

output impedance:

[begin][home]


sensitive active MOS antenna with gain

This antenna is constructed to optimize the sensitivity by choosing the max. signal to noise relation. The electronic circuit is reduced to one dual gate MOS-transistor, a BF908 by NXP and a collector stage. This amplifier is for nonsensitive receivers with high noise figur.

Specifications:

bandwidth: 10 kHz - 120 MHz

elektronical amplification: 9 - 14 dB

equiv. input-noise voltage: 1.8 nV/SQRT(Hz) @ 1 MHz

max. EMF rms: 0.25 V/m

intermodulation 2. order (ui~100 uV, 1 MHz, 2 MHz): -70 dB

power: 11 mA at 14-25 V over power-supply 230 V

output resistance: 50 Ohm

dimensions: 870 mm x 80 mm

circuit diagram:

gain:

intermodulation:

output impedance:

[begin][home]


sensitive tube-active-antenna

This antenna is constructed to optimize the sensitivity by choosing the max. signal to noise relation. Because of the tubes (cascode-circuit, 6CW4) the operation in direct enviroment of transmitters is possible. This antenna is EMP-safe. Noise-matching can be astablished until about 30 MHz. This circuit is transformerless because a plate-base stage with 50 Ohm impedance is the output.

Specifications:
bandwidth: 10 kHz - 30 MHz

electronical amplification: 1.3 dB

equiv. input-noise voltage: 2.8 nV/SQRT(Hz) @ 1 MHz

max. EMF rms: > 20 Veff./m

intermodulation 2. order (ui~100uV, 1 MHz, 2 MHz): -63 dB

outpur resistance: 50 Ohm

circuit diagram:

gain:

intermodulation:

output impedance:

[begin][home]


sensitive tube-active-antenna

This antenna is constructed to optimize the sensitivity by choosing the max. signal to noise relation. Because of the tube (cathode-base-circuit, 6CW4) the operation in direct enviroment of transmitters is possible. This antenna is EMP-safe. Noise-matching can be astablished until about 40 MHz. This circuit is transformerless because a plate-base stage with 50 Ohm impedance is the output.

Specifications:

bandwidth: 10 kHz - 40 MHz

electronical amplification: 0 dB

equiv. input-noise voltage: 2.2 nV/SQRT(Hz) @ 1 MHz

max. EMF rms: > 20 Veff./m

intermodulation 2. order (ui~100uV, 1 MHz, 2 MHz): -67 dB

outpur resistance: 50 Ohm

circuit diagram:

gain:

intermodulation:

output impedance:

[begin][home]


sensitive tube-active-antenna

This antenna is constructed to optimize the sensitivity by choosing the max. signal to noise relation. Because of the tube (cathode-base-circuit, EC81) the operation in direct enviroment of transmitters is possible. This antenna is EMP-safe.Noise-matching can be astablished until about 30 MHz.

Calculations for the transformer [here].

Specifications:

bandwidth: 10 kHz - 70 MHz

electronical amplification: -1.42 dB

equiv. input-noise voltage: 1.9 nV/SQRT(Hz) @ 1 MHz

max. EMF rms: > 20 Veff./m

intermodulation 2. order (ui~100uV, 1 MHz, 2 MHz): -68 dB

outpur resistance: 50 Ohm

circuit diagram:

gain:

intermodulation:

output impedance:

[begin][home]


sensitive tube-active-antenna

This antenna is constructed to optimize the sensitivity by choosing the max. signal to noise relation. Because of the tube (cathode-base-circuit, 6CW4) the operation in direct enviroment of transmitters is possible. This antenna is EMP-safe. Noise-matching can be astablished until about 100 MHz. The calculation of an passive antenna for this electronic causes a lenght of 47 cm by a diameter of 150 mm.

Calculations for the transformer [here].
Calculation of the lenght of a passive vertical antenna for this [here].

Specifications:

bandwidth: 10 kHz - 120 MHz

electronical amplification: +1.11 dB

equiv. input-noise voltage: 1.6 nV/SQRT(Hz) @ 1 MHz

max. EMF rms: > 20 Veff./m

intermodulation 2. order (ui~100uV, 1 MHz, 2 MHz): -74 dB

outpur resistance: 50 Ohm

circuit diagram:

gain:

intermodulation:

output impedance:

[begin][home]


active vertical wideband-antenna 100 MHz - 2 GHz

Wideband antenna with very low noise. The passive antenna-part is matched to the electronic, a MMIC type BGA 2012 from Philips, by a micro-strip-line.
Some computations for this antenna You find [here].

Specifications:
direction-diagramm 100 MHz at 10 m heightdirection-diagramm 2 GHz at 10 m heightdirection-diagramm 3 GHz at 10 m height

bandwidth: 100 MHz - 2 GHz

antenna-gain: 10 dBi / 2 GHz

electronical amplification: 16 dB

equiv. input-noise voltage: 0.6298 nV/SQRT(Hz) - noise figure: 1.7 dB

voltage: 7 - 16 V=

current: 18 mA / 12 V=

impedance: 50 Ohm N-plug

dimensions: 420 mm x 85 mm

<

circuit diagram:

filter:

Layout 20 mm x 44 mm with transmission line:

[begin][home]


cross-dipol antenna for 137.5 MHz

This antenna was build to receive weather-satellites at 137.5 MHz and the 2 m-band.The antenna-height over the radials is choosen, that the gain in the antenna-diagram is improved for little and low elevation. The max. gain is 7.6 dBi. The dipols are so connectet over transmissen lines, that cirular left or right polarized waves can be received, it must be switched. A low noise amplifier is added to match the lines to 50 ohms.

Specifications:

bandwidth: 132 MHz - 146 MHz

electronical amplification: 20 dB

noise: 2 dB

antenna-gain: 7.6 dBi

current: 45 mA bei 12 V

impedance: 50 Ohm

dimensions: 1000 mm x 600 mm

a view at the circuit diagram:

[begin][home]


500 W RMS Matchbox in Duplex-PI-Circuit:

With 2 vacuum-Cs up to 42 A and an aircooled roller-inductor from 1.5 MHz to 60 MHz to antennas from 5 Ohms to 500 Ohms. Also, there is the possibility to match RX-antennas with impedances from 5 Ohms to 2000 Ohms independent from the TX-antenna.

Specifications:

frequency-area: 1.5 MHz - 60 MHz

input impedance: 50 Ohms

max. power 500 Wrms

duplex matching

RX-Collins 5 Ohm to 2000 Ohms

TX-Collins 5 Ohm to 500 Ohms

power: 230 V~ 50 Hz

dimensions (B/H/T): 760 mm x 345 mm x 320 mm

weight: 28 Kg

a view at the circuit:

[begin][home]