high-frequency

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 320 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.

This active antenna with amplification is suitable for less sensitive receivers.

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

Specifications:
cylinder antenna	whip 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): -54 dB u. -50 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:

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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).

circuit diagram:

gain:

intermodulation:

high sensitive active antenna 10 kHz - 530 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.

circuit diagram:

gain:

intermodulation:

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:

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. R4 can be designed as a 39 kOhm fixed resistor and 50 kOhm potentiometer and the gain set over 25 dB.

circuit diagram:

gain:

intermodulation:

output impedance:

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 150 MHz. This circuit is transformerless because a plate-base stage with 50 Ohm impedance is the output.

Specifications:
bandwidth: 10 kHz - 150 MHz electronical amplification: 0 dB equiv. input-noise voltage: 2.19 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:

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 78 MHz. This circuit is transformerless because a plate-base stage with 50 Ohm impedance is the output.

circuit diagram:

gain:

intermodulation:

output impedance:

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].

circuit diagram:

gain:

intermodulation:

output impedance:

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].

circuit diagram:

gain:

intermodulation:

output impedance:

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 height	direction-diagramm 2 GHz at 10 m height	direction-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= power: 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:

active hor. Quad wideband-antenne 100 MHz - 2 GHz

Wideband antenna with very low noise. The passive quad-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 any height
enlarge picture	bandwidth: 100 MHz - 2 GHz antenna-gain: 9 dBi / 1 GHz electronical amplification: 16 dB equiv. input npoise voltage: 0.6298 nV/SQRT(Hz) - noise figure: 1.7 dB voltage: 7 - 16 V= power: 18 mA / 12 V= impedance: 50 Ohm N-Stecker dimensions: (H/B/L): 116 mm x 513 mm x 513 mm

circuit diagramm:

filter:

Layout 20 mm x 44 mm:

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:

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:

reference frequency generator

The frequency reference works with a 10 MHz OCXO and can be calibrated and adjusted e.g. via a GNSSDO. In practice, however, the Taitien OCXO in long-term usage is more accurate than 0.1 ppb, as measurements have shown. The specifications below are taken from the data sheet.

Specifications:
	output 1: 1 MHz TTL Square output 2: 2 MHz TTL Square output 3: 10 MHz TTL Square output 4: 10 MHz Sine 10 dBm frequency stability: 3 ppb initial accuracy: 100 ppb after 15 minutes turn on power           1 ppb after 45 minutes power: 5 V = power supply 2.5 A

view at the circuit: