Ultra-wideband (UWB) and multiband antennas for RF, microwaves, and UWB

Multiband and Ultra-Wideband Vertically Polarized Omni Antennas

Magnetic Sciences

Several new efficient antennas for multiband or ultra-wideband (UWB) on-the-move military and commercial communications were recently developed at Magnetic Sciences, for the following applications:

(a)

Multiband operation, reducing the number of antennas required

(b)

Ultrawideband (UWB) communications

(c)

Increasing communications range by reducing loss over wide bandwidths

These antennas offer improved performance compared to existing omni multiband antennas, including wider instantaneous frequency bandwidth, lower loss, higher low-angle gain and range, and higher power handling.

Table I. Vertically Polarized Multiband/UWB Omni Antenna Models Tested

Notes on Table I:

Column (a). Many more were also tested, only about 15% of them are listed in this table.

Column (b). Vertical height of antenna in inches from feed point of antenna.

Column (c). Lists the low frequency end of the frequency range meeting 3:1 VSWR or better (on 50-ohm feed line), with no tuning or matching needed. At this frequency and higher, the measured antenna VSWR is better than 3:1 at almost all freq. The antenna can still be used below this frequency, but a worse VSWR or some matching or tuning would be required. The high end of this low VSWR range is well above 3000 MHz and can be extended much higher if desired.

Column (d). Same as column (c) except below 2:1 VSWR at almost all frequencies.

Column (e). Very rough estimate of ohmic losses through a narrowband HF tuner matching this antenna in the lower portion of the HF band (2 - 5 MHz), these losses (S21) would improve as frequency increased. A low radiation resistance is a problem at lower frequencies since the antenna is electrically small (less than about 0.1 wavelengths long). A very low radiation resistance results in increased ohmic loss in the antenna and also in any tuners or impedance matching circuits. It therefore affects the gain, as shown in this column.

Table II. Connectors Available for These Antennas, with Power Ratings

(Use DIN or N connector for larger antennas, use TNC, SMA, or K for smaller antennas)

Notes on Table II: x = Square Root of Frequency in GHz (for example for 250 MHz, x = 0.5). Typical power and loss ratings for most applications are shown. Actual rating will depend on dielectric type, temperature, cooling, altitude, humidity, and frequency. The Average Power includes a safety factor which is less than 2, exact performance depends mainly on cable dielectric melting point, and also on other factors.

Vertical

Omnidirectional in Azimuth (doughnut shaped)

50 Ohms

See Table I

Several types available, see Table II

Depends on connector, see Table II

Polarization

Pattern

Impedance

Frequency band

VSWR

Connector

Power Handling

Gain

(a) Antenna Model

RMC9

RMC12

RMC20

RMC55

RMC71

W96-9

W96-14

W96-22

W144-9

W144-14

W144-22

DW96-9

DW96-14

DW96-22

INVL54-96-9

INVL54-96-22

(b) Antenna Height

14"

38"

48"

96"

144"

96"

60"

3:1 VSWR

290 MHz

200 MHz

130 MHz

50 MHz

32 MHz

310 MHz

195 MHz

140 MHz

320 MHz

200 MHz

125 MHz

300 MHz

200 MHz

130 MHz

310 MHz

130 MHz

(d) Start Freq

2:1 VSWR

375 MHz

285 MHz

190 MHz

420 MHz

330 MHz

375 MHz

255 MHz

190 MHz

395 MHz

230 MHz

190 MHz

320 MHz

260 MHz

140 MHz

385 MHz

200 MHz

(e) HF Tuner

Loss

-17 dB

-15 dB

-11 dB

-7 dB

-5.5 dB

-3.5dB

-2 dB

-3.5 dB

-2.5 dB

General Specifications

Connector

Type

DIN-7/16

UHF (PL259)

TNC

BNC

SMA

Average Power, Watts

2800/x

570/x

285/x

95/x

Peak Power (factor of 2 safety)

40 kW

10 kW

5.6 kW

2.5 kW

Max Operating Frequency, GHz

Connector Insertion Loss, dB

0.03x

0.05x

0.10x

0.03x

Features and Benefits

* Ultra-wideband Antennas, with multiple decades of instantaneous frequency bandwidth with low loss and low VSWR.

* Useful for multiband radio or ultrawideband (UWB) communications, and

* Multiband antenna reduces # antennas, space, visibility, pattern blockage, EMI, switching, holes in platform, logistics

* No need to tune or resistively load the antenna or trade-off gain for bandwidth. Reduces loss and improves gain.

* Can be used on-the-move or stationary, and has omni pattern. No need to stop; uninterrupted communications while in motion

* Rugged; can use in rough terrain

The antennas operate over a wide range of frequencies so that each antenna can be used for multiple bands and multiple channels. No tuning is needed to match these antennas to 50 ohms over a very wide instantaneous frequency range, which permits operation at any frequency or at multiple frequencies simultaneously within the instantaneous frequency range given in Table I, and also operation with very wideband waveforms, UWB, or with multiband radios. Frequency duplexers or multiplexers can also be provided so several transmitters can simultaneously use one antenna.

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